Obstetrics

🤰 Obstetrics anatomy, physiology and pharmacology — the foundation page for the Obstetrics chapter. Pregnancy changes almost every organ system: blood volume rises by half, creatinine falls, the blood becomes prone to clot and the airway becomes harder to manage. Knowing what is normal in pregnancy — and what isn't — is essential for every doctor who sees pregnant women, as is knowing which drugs are safe. This page covers pelvic and fetal anatomy, the placenta, maternal physiology, labour and breastfeeding, and prescribing in pregnancy.
Your four questions for every pregnant patient: Is this finding normal for pregnancy at this gestation — or a sign of disease? How does pregnancy change the risk (clotting, infection, airway, blood loss)? Is this drug safe for the fetus and breastfeeding baby — and is the dose right for pregnancy? Is undertreating the mother a bigger risk than the drug?

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Uterus, Cervix, Ovaries and Blood Supply

• Uterus — muscular organ (myometrium) lined by endometrium (decidua in pregnancy); fundus, body, lower segment (forms in late pregnancy — site of the caesarean incision) and cervix; usually anteverted and anteflexed.
• Growth — from about 50 g to about 1 kg; palpable above the symphysis at 12 weeks, at the umbilicus at 20 weeks, at the xiphisternum at about 36 weeks; symphysis–fundal height in centimetres ≈ gestation in weeks from 24 weeks (plotted on customised growth charts).
• Cervix — collagen-rich; remains closed during pregnancy, then ripens (softens, shortens, effaces, dilates) under prostaglandins at term; cervical length on scan predicts preterm birth (short cervix — progesterone or cerclage).
• Fallopian tubes — fimbriae, infundibulum, ampulla (site of fertilisation and commonest site of ectopic pregnancy), isthmus, interstitial part (dangerous ectopic site — heavy bleeding).
• Ovaries — follicles; the corpus luteum makes progesterone to support early pregnancy until the placenta takes over (8–10 weeks).
• Blood supply:
  • Uterine artery (from the internal iliac) — crosses over the ureter near the cervix ("water under the bridge") — ureteric injury risk at hysterectomy and caesarean section.
  • Ovarian artery (from the aorta) — anastomoses with the uterine artery.
  • Uterine blood flow at term — about 500–750 mL per minute (from about 50 mL/min) — so postpartum haemorrhage can be catastrophic within minutes; bleeding is controlled mainly by myometrial contraction compressing the vessels ("living ligatures").
• Lymphatics and nerves — uterus T10–L1 (labour pain of the first stage); cervix, vagina and perineum via the pudendal nerve (S2–S4 — second stage pain; pudendal block).

Pelvic Floor and Perineum

• Pelvic floor — the levator ani (pubococcygeus, puborectalis, iliococcygeus) and coccygeus — supports the pelvic organs, maintains continence, guides the fetal head to rotate during birth; supplied by S3–S4 and the pudendal nerve.
• Perineal body — central fibromuscular point between the vagina and anus where several muscles meet — torn or cut (episiotomy) at birth.
• Anal sphincters — external (skeletal — voluntary — pudendal nerve) and internal (smooth — involuntary).
• Perineal tears (RCOG):

  Degree	Structures involved
  First	Perineal skin and vaginal mucosa only
  Second	Perineal muscles (not the anal sphincter)
  Third	Anal sphincter — 3a under 50% of external sphincter; 3b over 50% of external sphincter; 3c external and internal sphincters
  Fourth	Anal sphincter complex and anorectal mucosa

• Obstetric anal sphincter injuries (OASI) — risk factors: first vaginal birth, instrumental birth (especially forceps), big baby, occipito-posterior position, prolonged second stage, Asian ethnicity — repaired in theatre; antibiotics, laxatives, physiotherapy; risk of faecal incontinence.
• Episiotomy — mediolateral (at about 60° from the midline) — reduces OASI in instrumental births.
• Long-term effects of childbirth — stress urinary incontinence, pelvic organ prolapse, faecal incontinence — pelvic floor muscle training in pregnancy and after birth (NICE NG210).

The Bony Pelvis

• Bones — two hip bones (ilium, ischium, pubis), sacrum and coccyx; joints — sacroiliac joints and pubic symphysis (loosened by relaxin in pregnancy — pelvic girdle pain, symphysis pubis dysfunction).
• Pelvic inlet (brim) — widest transversely (about 13 cm); anteroposterior (obstetric conjugate — sacral promontory to the back of the symphysis) about 11 cm — the fetal head usually enters transversely (occipitotransverse).
• Mid-cavity — roughly round; the ischial spines project inwards — the narrowest part — the reference point for station (0 at the spines; −2 above, +2 below) and the landmark for pudendal block.
• Pelvic outlet — widest anteroposteriorly — so the head rotates to occipito-anterior to be born.
• Pelvic shapes — gynaecoid (round inlet — most women — favourable), android (heart-shaped — deep transverse arrest, OP), anthropoid (long AP — OP), platypelloid (flat — rare).
• Cephalopelvic disproportion — the head can't pass the pelvis — prolonged labour, failure to progress — caesarean section; pelvimetry is no longer routinely used.
• Engagement — the widest part of the head (biparietal diameter) has passed through the inlet — usually from 36 weeks in first pregnancies, may be in labour in later pregnancies; assessed in fifths palpable abdominally (2/5 or fewer palpable = engaged).

The Fetal Skull, Lie, Presentation and Position

• Fetal skull — bones not yet fused; sutures (sagittal, coronal, lambdoid) and fontanelles:
  • Anterior fontanelle (bregma) — diamond-shaped — closes by about 18 months; bulging (raised ICP, meningitis) or sunken (dehydration).
  • Posterior fontanelle — triangular (where sagittal meets lambdoid sutures) — felt on vaginal examination to determine position.
  • Moulding — overlapping of skull bones in labour (excessive moulding suggests obstruction).
• Presenting diameters depend on head flexion:

  Attitude	Diameter	Size and outcome
  Vertex — well flexed	Suboccipitobregmatic	About 9.5 cm — normal birth
  Vertex — deflexed (often OP)	Occipitofrontal	About 11.5 cm — longer labour
  Brow	Mentovertical	About 13–13.5 cm — can't deliver vaginally (at term) — caesarean
  Face (fully extended)	Submentobregmatic	About 9.5 cm — mento-anterior can deliver; mento-posterior can't

• Lie — relation of the fetal long axis to the uterus — longitudinal, transverse, oblique (unstable lie near term — cord prolapse risk).
• Presentation — the part entering the pelvis first — cephalic (about 96% at term), breech (about 3–4% at term — external cephalic version at 36–37 weeks), shoulder (transverse lie).
• Position — relation of the denominator (occiput in vertex presentation) to the maternal pelvis — occipito-anterior (OA) is most favourable; occipito-posterior (OP) — backache, longer labour, more instrumental birth.
• Station — level of the presenting part relative to the ischial spines.

Conception and Implantation

• Dating — gestation is counted from the first day of the last menstrual period (about 2 weeks before conception); term is 37+0 to 41+6 weeks; estimated due date is 40 weeks (Naegele's rule — LMP + 9 months + 7 days); the dating scan (crown–rump length, 10–14 weeks) is more accurate.
• Ovulation — LH surge → release of the oocyte about day 14 of a 28-day cycle; the oocyte survives about 24 hours, sperm up to 5 days.
• Fertilisation — in the ampulla of the tube → zygote → morula → blastocyst reaches the uterus at about day 5.
• Implantation — days 6–10 after fertilisation — the trophoblast (outer cell layer) invades the decidua; syncytiotrophoblast secretes hCG (detectable in blood about 8–10 days after conception — basis of pregnancy tests).
• Embryonic period — weeks 3–8 after conception (weeks 5–10 of gestation) — organogenesis — the most sensitive time for structural birth defects; the heart beats from about 6 weeks of gestation.
• Fetal period — from 10 weeks of gestation — growth and maturation.
• Twins:
  • Dizygotic (two eggs — about two-thirds) — always dichorionic diamniotic; more with IVF, older age, family history, Black African ancestry.
  • Monozygotic (one egg splits) — chorionicity depends on timing of split; monochorionic twins share a placenta — risk of twin-to-twin transfusion syndrome (more frequent scans); monoamniotic — cord entanglement.
  • Chorionicity is determined at the first-trimester scan (lambda sign — dichorionic; T sign — monochorionic).

The Placenta

• Structure — disc about 20 cm across and 500 g at term; fetal chorionic villi bathed in maternal blood in the intervillous space (haemochorial placenta — maternal and fetal blood don't mix but are separated by thin layers); umbilical cord — one vein (oxygenated blood to the fetus) and two arteries (single umbilical artery — associated with anomalies), in Wharton's jelly.
• Spiral artery remodelling — trophoblast invades maternal spiral arteries in the first half of pregnancy, converting them into wide, low-resistance vessels — failure causes poor placental perfusion → pre-eclampsia and fetal growth restriction (high uterine artery Doppler resistance).
• Functions:
  • Gas exchange — by diffusion; fetal haemoglobin (HbF — α2γ2) has a higher oxygen affinity than adult Hb (less 2,3-DPG binding); the "double Bohr effect" aids transfer.
  • Nutrients — glucose (facilitated diffusion — fetal glucose follows maternal — macrosomia in poorly controlled diabetes), amino acids (active transport), fatty acids, iron and calcium (active).
  • Waste removal — CO₂, urea, bilirubin.
  • Hormone production — hCG, progesterone, oestrogens, hPL.
  • Immunity — IgG crosses (via neonatal Fc receptors, mainly in the third trimester) — passive immunity for the baby (boosted by maternal vaccination — pertussis, flu, RSV, COVID-19); also harmful IgG — anti-D (haemolytic disease of the newborn), TSH receptor antibodies (neonatal thyrotoxicosis), anti-Ro (congenital heart block), acetylcholine receptor antibodies (neonatal myasthenia), therapeutic monoclonal antibodies. IgM doesn't cross.
  • Partial barrier — most drugs cross (small, lipid-soluble, unionised); large molecules don't (heparin, insulin); many infections cross (TORCH — toxoplasma, rubella, CMV, HSV, syphilis, HIV, Zika, listeria, parvovirus B19).
• Placental problems — praevia (low-lying — painless bleeding; no vaginal examination), abruption (painful bleeding, tense uterus — concealed bleeding), accreta spectrum (abnormally adherent — after previous caesarean with praevia — massive haemorrhage), insufficiency (FGR, stillbirth), retained placenta.

Hormones of Pregnancy

Hormone	Source and pattern	Effects and clinical relevance
hCG	Syncytiotrophoblast; doubles about every 48 hours early; peaks at 8–12 weeks	Maintains the corpus luteum; pregnancy tests; very high in molar pregnancy and twins — hyperemesis; TSH-like effect — gestational thyrotoxicosis; serial levels in pregnancy of unknown location
Progesterone	Corpus luteum, then placenta from 8–10 weeks	Relaxes smooth muscle (uterine quiescence, reflux, constipation, ureteric dilatation, varicose veins), raises minute ventilation, raises body temperature
Oestrogens (mainly oestriol)	Placenta (using fetal adrenal precursors)	Uterine growth and blood flow, breast development, raise clotting factors and binding proteins (TBG, CBG)
Human placental lactogen	Placenta — rises with placental mass	Insulin resistance (diverts glucose to the fetus) — gestational diabetes; lipolysis
Relaxin	Corpus luteum and placenta	Ligament laxity — pelvic girdle pain; vasodilatation
Prolactin	Anterior pituitary (enlarges in pregnancy)	Prepares breasts for lactation (milk held back until progesterone falls after birth)
CRH	Placenta — rises exponentially late in pregnancy	May act as a "clock" for the timing of labour
Oxytocin	Posterior pituitary	Uterine contraction in labour (receptors increase at term); milk let-down

Fetal Development and Circulation

• Fetal circulation — designed to bypass the lungs and liver:
  • Oxygenated blood from the placenta in the umbilical vein → ductus venosus (bypasses the liver) → IVC → right atrium.
  • Most crosses the foramen ovale → left atrium → left ventricle → aorta → brain and heart (best-oxygenated blood).
  • SVC blood → right ventricle → pulmonary artery → ductus arteriosus (bypasses the high-resistance lungs) → descending aorta.
  • Two umbilical arteries return deoxygenated blood to the placenta.
• Changes at birth:
  • First breaths expand the lungs → pulmonary vascular resistance falls → more pulmonary blood flow → left atrial pressure rises → foramen ovale closes (flap).
  • Cord clamping removes the low-resistance placenta → systemic resistance rises.
  • Ductus arteriosus constricts within hours to days (rising oxygen, falling prostaglandins) — patent ductus in preterm babies (closed with NSAIDs — indometacin, ibuprofen — or paracetamol); prostaglandin E keeps it open in duct-dependent congenital heart disease.
  • Persistent pulmonary hypertension of the newborn — failure of PVR to fall (meconium aspiration, sepsis, SSRIs in late pregnancy — small risk).
• Fetal lungs — surfactant production begins around 24 weeks and matures by 34–36 weeks — respiratory distress syndrome in preterm babies — antenatal corticosteroids accelerate maturation.
• Fetal kidneys — make urine from about 10–12 weeks — the main source of amniotic fluid after 16 weeks.
• Fetal growth — monitored by symphysis–fundal height and ultrasound (estimated fetal weight, abdominal circumference); small for gestational age (below 10th centile) vs fetal growth restriction (failure to reach growth potential — placental); macrosomia (diabetes, obesity — shoulder dystocia).
• Fetal heart rate — normal 110–160 bpm; cardiotocography (CTG) in labour.

Amniotic Fluid

• Functions — protects the fetus, allows movement and lung development (fetal breathing), prevents cord compression, antimicrobial, temperature control.
• Production and removal — early from the membranes; after 16 weeks mainly fetal urine plus lung fluid; removed by fetal swallowing and absorption; volume peaks at about 800 mL–1 L at 34–36 weeks then falls.
• Measured by ultrasound — deepest vertical pool or amniotic fluid index.
• Oligohydramnios (too little):
  • Causes — preterm prelabour rupture of membranes, fetal growth restriction (placental insufficiency — reduced renal perfusion), renal agenesis or obstruction (posterior urethral valves), post-term pregnancy, drugs (ACE inhibitors and ARBs, NSAIDs after 20 weeks).
  • Consequences — pulmonary hypoplasia (if early and severe), limb contractures, Potter sequence, cord compression in labour.
• Polyhydramnios (too much):
  • Causes — maternal diabetes (fetal polyuria), impaired fetal swallowing (oesophageal atresia, duodenal atresia, neuromuscular conditions, anencephaly), twin-to-twin transfusion, fetal anaemia, infections, idiopathic.
  • Consequences — maternal discomfort and breathlessness, preterm labour, malpresentation, cord prolapse, placental abruption, postpartum haemorrhage (overdistended uterus).
• Amniotic fluid embolism — rare, catastrophic — sudden collapse, hypoxia, DIC in labour or soon after.
• Meconium-stained liquor — fetal maturity or distress — continuous monitoring; meconium aspiration risk.

Cardiovascular Changes

• Plasma volume rises by about 40–50% (by 32–34 weeks); red cell mass by about 20–30% → physiological (dilutional) anaemia.
• Cardiac output rises by about 30–50% (mostly by 20–24 weeks) — stroke volume and heart rate (by 10–20 bpm) both increase.
• Systemic vascular resistance falls (progesterone, nitric oxide, placental low-resistance circulation) → BP falls in the first and second trimesters (lowest about 20–24 weeks) and returns to pre-pregnancy levels by term — hypertension in early pregnancy is usually pre-existing; new hypertension after 20 weeks suggests gestational hypertension or pre-eclampsia.
• Aortocaval compression — from about 20 weeks, the uterus compresses the IVC (and aorta) when supine → reduced venous return → supine hypotension, fetal distress — position women in left lateral tilt; in cardiac arrest, use manual left uterine displacement and plan resuscitative hysterotomy within 5 minutes if over 20 weeks.
• Normal findings — ejection systolic flow murmur, third heart sound, mild peripheral oedema, palpitations, ectopics; ECG — left axis shift, small Q and inverted T in III.
• Abnormal (investigate) — diastolic murmurs, loud or pansystolic murmurs, significant arrhythmias, breathlessness at rest, orthopnoea, chest pain.
• Labour and delivery — each contraction returns about 300–500 mL of blood to the circulation; immediately after birth, autotransfusion from the contracted uterus raises cardiac output further — women with heart disease (mitral stenosis, pulmonary hypertension, cardiomyopathy) are at highest risk in labour and the first days postpartum.
• Hidden blood loss — healthy young women compensate for large blood loss (up to about 30%) before BP falls — tachycardia and the clinical picture matter more than BP.

Respiratory Changes

• Minute ventilation rises by about 40–50% — mainly from increased tidal volume (respiratory rate barely changes) — driven by progesterone.
• Result — compensated respiratory alkalosis — PaCO₂ about 3.7–4.2 kPa, bicarbonate about 18–22 mmol/L, pH slightly raised — a "normal" PaCO₂ of 5.3 kPa in a pregnant asthmatic signals tiring and impending respiratory failure.
• Functional residual capacity falls by about 20% (diaphragm pushed up) and oxygen consumption rises about 20% → pregnant women desaturate very quickly when apnoeic (pre-oxygenate before intubation).
• Airway — mucosal oedema and capillary engorgement (nasal congestion, nosebleeds), breast enlargement, weight gain, aspiration risk (relaxed lower oesophageal sphincter, delayed gastric emptying in labour) — difficult and failed intubation is more common — regional anaesthesia preferred for caesarean section.
• Physiological breathlessness of pregnancy — common, gradual, not limiting, normal examination and oxygen saturation — but always consider PE, cardiomyopathy, asthma and anaemia.
• Spirometry — FEV₁ and peak flow largely unchanged (use normal values).
• Infections are more severe — influenza, varicella pneumonia, COVID-19 — vaccinate.

Renal Changes

• Renal plasma flow and GFR rise by about 50% from early pregnancy.
• Lower creatinine and urea — creatinine typically about 45–70 µmol/L; a creatinine that would be "normal" outside pregnancy (e.g. 90 µmol/L) may indicate significant kidney impairment.
• Glycosuria — increased filtered load and reduced tubular reabsorption — common, so glycosuria doesn't diagnose diabetes (oral glucose tolerance test).
• Proteinuria — slightly increased — up to about 300 mg/day is normal; a urine protein:creatinine ratio over 30 mg/mmol is significant (pre-eclampsia).
• Urate — falls in early pregnancy (higher GFR), rises towards term; rising urate is associated with pre-eclampsia.
• Physiological hydronephrosis — progesterone relaxes the ureters and the uterus compresses them (right more than left — dextrorotation of the uterus) → urinary stasis → asymptomatic bacteriuria is more likely to cause pyelonephritis — screen and treat bacteriuria in pregnancy (preterm birth risk).
• Increased frequency — bladder compression (first and third trimesters), nocturia.
• Drug clearance — renally cleared drugs are cleared faster (e.g. LMWH, lithium, some antibiotics) — doses may need increasing; levels may fall.
• Fluid retention — about 6–8 L total body water gain — oedema of the ankles is common (but sudden facial or hand oedema with hypertension suggests pre-eclampsia).

Blood and Clotting

• Anaemia thresholds (BSH) — Hb under 110 g/L in the first trimester, under 105 g/L in the second and third trimesters, under 100 g/L postpartum.
• Iron requirements rise (fetus, placenta, red cell mass) — iron deficiency is common — check ferritin; oral iron (alternate-day dosing may improve absorption), IV iron later in pregnancy if needed; folic acid 400 micrograms before conception to 12 weeks (5 mg if high risk).
• Hypercoagulable state — prepares for blood loss at birth:
  • Increased fibrinogen, factors VII, VIII, X and von Willebrand factor.
  • Decreased protein S and fibrinolysis.
  • Plus venous stasis (uterine compression of pelvic veins — left leg DVT more common) and vascular injury at delivery.
  • VTE risk is raised about 4–6-fold in pregnancy and highest in the first 6 weeks postpartum (especially after caesarean) — VTE is a leading direct cause of maternal death in the UK — risk assessment at booking, admission and after birth; LMWH prophylaxis (RCOG Green-top 37a).
• D-dimer rises through pregnancy — not useful for excluding VTE; imaging is needed (leg ultrasound, CTPA or V/Q).
• Platelets — fall slightly; gestational thrombocytopenia (mild, usually over 70–80 × 10⁹/L, third trimester, harmless) vs ITP, pre-eclampsia, HELLP, TTP.
• White cell count rises (neutrophilia — up to about 15 × 10⁹/L; higher in labour and after steroids).
• ESR rises (not useful); fibrinogen about 4–6 g/L at term — a fibrinogen under 2 g/L during PPH predicts severe bleeding (replace).
• Rhesus status — RhD-negative women carrying RhD-positive babies can make anti-D after sensitising events — anti-D immunoglobulin prophylaxis (routine antenatal at 28 weeks, and after sensitising events and birth); fetal RhD genotyping from cell-free DNA targets treatment.

Endocrine and Metabolic Changes

• Glucose metabolism:
  • First trimester — increased insulin sensitivity (hypoglycaemia risk in type 1 diabetes, especially with vomiting).
  • Second and third trimesters — insulin resistance (hPL, progesterone, cortisol, placental growth hormone) — insulin requirements rise 2–3-fold in type 1 diabetes; unmasks gestational diabetes (risk factors — BMI over 30, previous macrosomic baby, previous GDM, family history, South Asian, Black or Middle Eastern ancestry — OGTT at 24–28 weeks).
  • After delivery — insulin resistance disappears rapidly — stop GDM treatment; reduce insulin in pre-existing diabetes immediately (hypoglycaemia risk).
• Thyroid:
  • hCG stimulates the TSH receptor → TSH falls in the first trimester (can mimic hyperthyroidism — gestational thyrotoxicosis with hyperemesis).
  • Thyroxine-binding globulin rises (oestrogen) → total T4 rises — measure free T4 and use trimester-specific ranges.
  • The fetus depends on maternal T4 until its thyroid works (about 12 weeks) — treat hypothyroidism promptly; women on levothyroxine should increase the dose by about 25–30% as soon as pregnancy is confirmed (e.g. two extra doses a week) and check TFTs.
  • Iodine needs rise.
• Pituitary — enlarges (lactotroph hyperplasia) — vulnerable to infarction with major PPH (Sheehan's syndrome — failure of lactation, amenorrhoea, hypopituitarism); macroprolactinomas can enlarge (visual field checks).
• Adrenal — cortisol (total and free) rises; aldosterone and renin rise.
• Calcium — gut absorption doubles (more calcitriol) to supply the fetal skeleton; vitamin D supplements recommended (10 micrograms daily).
• Lipids — cholesterol and triglycerides rise (don't check routinely; stop statins).
• Weight gain — typically about 10–15 kg (fetus, placenta, fluid, blood, uterus, breasts, fat).

Gut, Liver, Skin and Musculoskeletal Changes

• Gut — progesterone relaxes smooth muscle:
  • Nausea and vomiting — common (peak 9–12 weeks, settles by 16–20 weeks) — linked to hCG (and GDF15); hyperemesis gravidarum — dehydration, weight loss over 5%, ketosis — antiemetics, fluids, thiamine (Wernicke's risk).
  • Reflux (relaxed lower oesophageal sphincter, uterine pressure), constipation (slow transit, iron), haemorrhoids.
  • Gallstones — bile stasis (progesterone) and supersaturation (oestrogen).
• Liver:
  • ALP rises (placental — up to 2–4 times normal) — normal; albumin falls; ALT, AST, bilirubin and GGT should be normal or slightly lower — raised transaminases are abnormal.
  • Pregnancy-specific liver disease — intrahepatic cholestasis of pregnancy (itching of palms and soles, raised bile acids), HELLP and pre-eclampsia, acute fatty liver of pregnancy (third trimester — vomiting, hypoglycaemia, coagulopathy — emergency delivery), hyperemesis.
• Skin — linea nigra, melasma (chloasma), striae gravidarum, spider naevi and palmar erythema (oestrogen), pruritus; pregnancy dermatoses (polymorphic eruption, pemphigoid gestationis).
• Musculoskeletal — relaxin and weight cause pelvic girdle pain, low back pain, lumbar lordosis, carpal tunnel syndrome (fluid retention), leg cramps.
• Immune system — modulated to tolerate the fetus — some autoimmune diseases improve (RA, MS — then flare postpartum), others may flare (SLE); some infections are more severe (influenza, varicella, listeria, malaria, hepatitis E, COVID-19).
• Eyes — corneal oedema (contact lens intolerance); visual disturbance with headache — think pre-eclampsia.

Normal Values in Pregnancy

Measure	Change	Clinical point
Haemoglobin	Falls	Anaemia under 110 (T1), under 105 (T2–3), under 100 postpartum
White cell count	Rises	Up to about 15 normal; higher in labour
Platelets	Fall slightly	Gestational thrombocytopenia usually over 70–80
Fibrinogen, factors VII, VIII, X	Rise	Hypercoagulable; fibrinogen under 2 g/L in PPH — severe
D-dimer	Rises	Not useful for VTE
ESR	Rises	Not useful
Creatinine	Falls (about 45–70)	"Normal" non-pregnant values may be abnormal
Urea	Falls	—
Protein:creatinine ratio	Slight rise	Over 30 mg/mmol significant
ALP	Rises (placental)	Up to 2–4 times normal
ALT, AST, bilirubin	Unchanged or lower	Raised = abnormal
Albumin	Falls	Adjust calcium; drug binding
TSH	Falls (T1)	Use trimester ranges; free T4
PaCO2	Falls (about 4 kPa)	"Normal" 5.3 kPa in asthma is dangerous
Bicarbonate	Falls (about 18–22)	Compensated respiratory alkalosis
Heart rate	Rises 10–20 bpm	Persistent over 100 — investigate
BP	Falls mid-pregnancy	New hypertension after 20 weeks — pre-eclampsia screen
Cholesterol, triglycerides	Rise	Don't measure routinely

Physiology of Labour

• Onset of labour — not fully understood; rising CRH, fetal cortisol, oestrogen:progesterone ratio, increased oxytocin receptors and gap junctions in the myometrium, local prostaglandins (cervical ripening and contractions); stretch.
• Ferguson reflex — stretch of the cervix and vagina → oxytocin release → stronger contractions (positive feedback).
• Stages of labour (NICE NG235):
  • First stage — latent (painful contractions with cervical change up to 4 cm) and established (regular contractions, progressive dilation from 4 cm); delay suspected if under 2 cm dilation in 4 hours (or slowing in parous women).
  • Second stage — full dilation (10 cm) to birth of the baby — passive then active (pushing); birth usually expected within 3 hours of the start of the active second stage in first labours and 2 hours in later labours.
  • Third stage — birth of the baby to delivery of the placenta — active management (IM oxytocin 10 units, delayed cord clamping, controlled cord traction) reduces PPH; prolonged if over 30 minutes (active) or 60 minutes (physiological).
• Mechanism of labour (cardinal movements) in a vertex presentation:
  • Engagement (often occipitotransverse at the inlet).
  • Descent.
  • Flexion (smallest diameter presents).
  • Internal rotation to occipito-anterior (at the pelvic floor).
  • Extension — the head is born.
  • Restitution — the head realigns with the shoulders.
  • External rotation — shoulders rotate to the AP diameter of the outlet.
  • Expulsion — anterior then posterior shoulder, then the body.
• The "3 Ps" of progress — Powers (contractions), Passenger (size, position, attitude), Passage (pelvis, soft tissues).
• Pain pathways — first stage — T10–L1 (uterus and cervix — visceral); second stage — S2–S4 (pudendal — somatic) — epidural covers both.
• Placental separation — signs — lengthening of the cord, a gush of blood, the uterus rising and becoming firm and globular.

The Puerperium and Breastfeeding

• Puerperium — the 6 weeks after birth as the body returns towards its non-pregnant state.
  • Uterine involution — at the umbilicus after birth, no longer palpable abdominally by about 10–14 days; lochia (red → brown → yellow-white) for up to 6 weeks — heavy or offensive lochia suggests retained tissue or endometritis.
  • Cardiovascular and renal changes reverse over weeks; VTE risk highest in the first 6 weeks.
  • Mood — "baby blues" (days 3–5 — transient), postnatal depression, postpartum psychosis (first 2 weeks — psychiatric emergency; higher risk with bipolar disorder).
  • Contraception — ovulation can return from about 3 weeks after birth if not breastfeeding; lactational amenorrhoea method (fully breastfeeding, amenorrhoeic, under 6 months).
• Lactation:
  • Prolactin — milk production — released in response to suckling; milk "comes in" on days 2–4 as progesterone falls after placental delivery (retained placenta delays it); dopamine inhibits prolactin (dopamine agonists — cabergoline — suppress lactation; dopamine antagonists — metoclopramide, domperidone — increase prolactin).
  • Oxytocin — milk ejection ("let-down") — also causes uterine cramps when feeding (helps involution); inhibited by stress and pain.
  • Colostrum — first milk — rich in IgA, protein and immune cells.
  • Benefits of breastfeeding — baby: fewer infections (gastroenteritis, otitis media, respiratory), lower risk of SIDS and obesity; mother: lower risk of breast and ovarian cancer, type 2 diabetes.
• Breast problems — engorgement, mastitis (continue feeding; flucloxacillin if infective), breast abscess (ultrasound and drainage).

Prescribing in Pregnancy — Principles

• Most drugs cross the placenta — but untreated maternal illness (epilepsy, asthma, depression, hypertension, diabetes, infection, VTE) is often a greater risk to mother and baby than the medicine — don't stop essential drugs abruptly.
• Timing of exposure:
  • Weeks 0–2 after conception (up to 4 weeks of gestation) — "all or nothing" — loss of the pregnancy or normal development.
  • Weeks 3–8 after conception (5–10 weeks of gestation) — organogenesis — structural birth defects.
  • Second and third trimesters — effects on growth and organ function (ACE inhibitors — fetal kidneys; NSAIDs — ductus arteriosus and kidneys; tetracyclines — teeth and bone; warfarin — fetal bleeding).
  • Near birth — neonatal effects (opioids — respiratory depression and withdrawal; benzodiazepines — "floppy baby"; SSRIs — neonatal adaptation syndrome; beta-blockers — neonatal hypoglycaemia and bradycardia).
• Pharmacokinetic changes — larger volume of distribution, faster renal clearance (LMWH, lithium), increased hepatic metabolism of some drugs (lamotrigine levels fall — monitor seizures and levels), lower albumin (higher free fraction — phenytoin), delayed gastric emptying in labour.
• Plan pregnancy — pre-conception counselling for women with chronic disease (switch teratogens before conception, high-dose folic acid, optimise control).
• Use — the lowest effective dose, drugs with the most experience, single agents where possible; avoid new drugs without data.
• Information sources — UK Teratology Information Service (UKTIS) and the patient site "best use of medicines in pregnancy (bumps)", BNF, specialist pharmacists.
• Pregnancy prevention programmes — valproate, isotretinoin and oral retinoids, topiramate (MHRA 2024), thalidomide-type drugs — highly effective contraception and annual review.

Teratogens and Drugs to Avoid

Drug	Fetal risk
Sodium valproate	Neural tube defects and other malformations (about 10%) and neurodevelopmental disorders (up to 30–40%) — not to be used in anyone who could become pregnant unless no alternative and a pregnancy prevention programme is in place (MHRA)
Carbamazepine, phenytoin, phenobarbital, topiramate	Malformations (NTDs, cleft lip and palate, heart defects); topiramate — cleft lip, low birth weight, possible neurodevelopmental effects; lamotrigine and levetiracetam are preferred (with folic acid 5 mg)
Warfarin	Embryopathy (weeks 6–12 — nasal hypoplasia, stippled epiphyses); later — fetal intracranial haemorrhage — switch to LMWH before 6 weeks (except some mechanical valves — specialist)
ACE inhibitors, ARBs	Second and third trimesters — fetal renal failure, oligohydramnios, skull hypoplasia, death — switch before or as soon as pregnancy is confirmed (labetalol, nifedipine)
Methotrexate, mycophenolate, leflunomide, cyclophosphamide	Major malformations, miscarriage — stop before conception (methotrexate 3 months — check current advice; leflunomide washout)
Isotretinoin and oral retinoids (acitretin)	Severe craniofacial, cardiac and CNS defects — pregnancy prevention programme
Lithium	Cardiac defects (Ebstein's anomaly — small absolute risk); neonatal toxicity — specialist decision; monitor levels (fall in pregnancy, rise after birth)
Tetracyclines (doxycycline)	Tooth discoloration and bone growth effects (from about 15 weeks)
Trimethoprim	Folate antagonist — avoid in the first trimester
Nitrofurantoin	Avoid at term — neonatal haemolysis (G6PD)
Aminoglycosides	Fetal ototoxicity
NSAIDs	Avoid from 20 weeks (oligohydramnios, fetal renal impairment) and in the third trimester (premature closure of the ductus arteriosus); possible miscarriage early
Statins	Stop in pregnancy (cholesterol needed for fetal development)
Misoprostol	Miscarriage; Möbius syndrome
Danazol, testosterone	Virilisation of female fetus
Radioiodine	Fetal thyroid ablation — contraindicated
Carbimazole	First-trimester embryopathy (aplasia cutis, choanal and oesophageal atresia) — propylthiouracil in the first trimester, then carbimazole
Alcohol, smoking, cocaine	Fetal alcohol spectrum disorder; growth restriction, stillbirth, abruption, SIDS
Live vaccines	MMR, varicella, BCG — avoid in pregnancy (inadvertent use isn't an indication for termination)
High-dose vitamin A	Teratogenic — avoid liver and liver products

Commonly Used Drugs in Pregnancy

• Analgesia — paracetamol (first line — lowest dose, shortest time); avoid NSAIDs (especially after 20 weeks); opioids short term if needed (neonatal monitoring if used near birth); codeine — avoid in breastfeeding.
• Antibiotics — penicillins (amoxicillin, phenoxymethylpenicillin), cephalosporins (cefalexin), nitrofurantoin (avoid at term), erythromycin (macrolide of choice if penicillin allergic); clindamycin; metronidazole (generally acceptable — avoid high single doses where possible). Avoid trimethoprim (first trimester), tetracyclines, quinolones (where alternatives exist), aminoglycosides (unless essential).
• UTI and asymptomatic bacteriuria — treat for 7 days with nitrofurantoin (not at term), amoxicillin (if sensitive) or cefalexin; test of cure.
• Antiemetics (nausea and hyperemesis — RCOG) — first line — cyclizine, promethazine, prochlorperazine, or doxylamine with pyridoxine (Xonvea); second line — metoclopramide (maximum 5 days — extrapyramidal effects) or ondansetron (very small increased risk of oral cleft in the first trimester — MHRA — discuss); third line — corticosteroids; thiamine with prolonged vomiting.
• Reflux — antacids and alginates, then ranitidine alternatives (famotidine) or omeprazole.
• Constipation — fibre, fluids, lactulose, ispaghula, senna.
• Antihypertensives — labetalol (first line — avoid in asthma), nifedipine (modified release), methyldopa (avoid postpartum — depression); stop ACE inhibitors and ARBs.
• Thromboprophylaxis and treatment — LMWH (doesn't cross the placenta; weight-based dosing); DOACs avoided.
• Asthma — continue inhalers (salbutamol, inhaled steroids, LABA) and oral steroids if needed — poorly controlled asthma is the bigger risk.
• Diabetes — insulin and metformin (safe); glibenclamide (some use); stop other oral agents (SGLT2, GLP-1 — stop before conception).
• Thyroid — levothyroxine (increase dose); propylthiouracil (first trimester) then carbimazole.
• Epilepsy — lamotrigine and levetiracetam preferred; folic acid 5 mg; never stop AEDs abruptly; vitamin K is no longer routinely given to mothers.
• Mental health — sertraline and other SSRIs commonly continued (small risks — PPHN, neonatal adaptation); avoid paroxetine (cardiac) where possible; perinatal mental health team.
• Immunosuppressants compatible with pregnancy — prednisolone (mostly inactivated by the placenta), hydroxychloroquine, azathioprine, sulfasalazine (with folic acid 5 mg), ciclosporin, tacrolimus, most anti-TNF drugs (certolizumab minimal transfer).
• Antihistamines — chlorphenamine, loratadine, cetirizine.
• Supplements — folic acid 400 micrograms (5 mg if high risk — previous NTD, AEDs, diabetes, BMI 30 or more, sickle cell, coeliac), vitamin D 10 micrograms daily; iron if deficient; avoid vitamin A supplements.
• Low-dose aspirin (75–150 mg from 12 weeks) — women at high risk of pre-eclampsia (NICE NG133).

Obstetric Drugs

Drug	Use and mechanism	Cautions
Oxytocin	Augmentation and induction of labour (IV infusion); third stage (10 units IM); PPH treatment	Uterine hyperstimulation (fetal distress), water intoxication (hyponatraemia) with large volumes, hypotension with rapid IV bolus
Carbetocin	Long-acting oxytocin analogue — PPH prevention at caesarean section	As oxytocin
Ergometrine (alone or as Syntometrine)	Sustained uterine contraction — PPH	Avoid in hypertension and pre-eclampsia (vasoconstriction), heart disease; vomiting
Carboprost (PGF2α — IM)	Refractory PPH	Avoid in asthma (bronchospasm); diarrhoea
Misoprostol (PGE1)	PPH, induction of labour, medical management of miscarriage and termination	Shivering, fever, diarrhoea; uterine hyperstimulation and rupture risk (previous caesarean)
Tranexamic acid	Antifibrinolytic — PPH (1 g IV within 3 hours — WOMAN trial)	Seizures at high doses; caution with VTE history
Dinoprostone (PGE2 — vaginal pessary or gel)	Cervical ripening and induction of labour	Hyperstimulation; caution with previous caesarean
Antenatal corticosteroids (betamethasone or dexamethasone — IM, 2 doses)	Fetal lung maturation (also reduce IVH and NEC) — preterm birth expected between 24+0 and 33+6 weeks (consider from 22 weeks and to 35+6 — NICE NG25)	Transient maternal hyperglycaemia (adjust insulin in diabetes); best effect if birth within 7 days
Magnesium sulfate	Seizure prophylaxis and treatment in eclampsia and severe pre-eclampsia; fetal neuroprotection (reduces cerebral palsy) in preterm birth before 30 weeks (consider to 34)	Toxicity — loss of reflexes, respiratory depression, cardiac arrest — monitor reflexes, respiratory rate, urine output; antidote calcium gluconate; reduce in renal impairment
Tocolytics — nifedipine, atosiban (oxytocin antagonist)	Delay preterm labour (24–48 hours) to allow steroids and transfer	Nifedipine — hypotension, headache; avoid indometacin late (ductus)
Anti-D immunoglobulin	Prevents RhD sensitisation in RhD-negative women	Routine at 28 weeks (or 28 and 34), after sensitising events, and after birth if baby RhD-positive (Kleihauer test for dose)
Labetalol (IV), hydralazine (IV), nifedipine	Severe hypertension in pregnancy (BP 160/110 or more)	Avoid over-rapid falls (fetal distress); labetalol — asthma
Cabergoline	Suppresses lactation (stillbirth, neonatal death, when breastfeeding is contraindicated)	Avoid in pre-eclampsia and hypertension

⚠️ Safety Pearl: In postpartum haemorrhage, choose uterotonics by the mother's conditions — no ergometrine if she has pre-eclampsia or hypertension, and no carboprost if she has asthma. Give tranexamic acid early (within 3 hours). And on magnesium sulfate, check patellar reflexes and breathing regularly — calcium gluconate reverses toxicity.

Drugs and Breastfeeding

• Most medicines are compatible with breastfeeding — the dose reaching the baby is usually under 10% of the maternal dose — the benefits of breastfeeding usually outweigh small risks; don't advise stopping breastfeeding without checking.
• Factors increasing transfer — low protein binding, lipid solubility, small molecular size, long half-life; premature or sick babies are more vulnerable.
• Generally compatible — paracetamol, ibuprofen, penicillins, cephalosporins, macrolides, LMWH and warfarin, labetalol, nifedipine, enalapril, insulin, metformin, levothyroxine, most inhalers, prednisolone, sertraline, lamotrigine (monitor baby), levetiracetam, hydroxychloroquine, sulfasalazine (caution in preterm or jaundiced babies), azathioprine, most biologics, most local anaesthetics.
• Avoid or use with caution:
  • Codeine and tramadol — contraindicated (CYP2D6 ultrarapid metabolisers — infant morphine toxicity and deaths).
  • Lithium — specialist decision (infant levels and toxicity).
  • Amiodarone (iodine — infant thyroid), radioactive iodine, cytotoxic drugs, retinoids.
  • High-dose aspirin (Reye's syndrome — low dose acceptable).
  • Combined hormonal contraception — may reduce milk supply in the first 6 weeks (progestogen-only methods preferred).
  • Dopamine agonists (cabergoline, bromocriptine) suppress lactation.
  • Benzodiazepines and sedating drugs — infant drowsiness (short courses of short-acting agents acceptable).
  • Doxycycline — short courses acceptable; avoid long courses.
• Methyldopa — avoid postpartum (depression) — switch to enalapril, nifedipine or labetalol (NICE NG133).
• Sources — Specialist Pharmacy Service (SPS) and the UK Drugs in Lactation Advisory Service (UKDILAS), LactMed, the BNF.

Obstetric Science at a Glance

Fact	Why it matters
Uterine blood flow 500–750 mL/min at term	PPH can kill in minutes — uterine contraction controls bleeding
Uterine artery crosses over the ureter	Ureteric injury at surgery
Inlet widest transversely, outlet widest AP	Head enters transverse, rotates to OA
Brow presentation (mentovertical 13.5 cm)	Can't deliver vaginally at term
Failed spiral artery remodelling	Pre-eclampsia and FGR
IgG crosses the placenta	Passive immunity; anti-D, TRAb, anti-Ro disease
hPL causes insulin resistance	Gestational diabetes after 24 weeks
hCG peaks 8–12 weeks	Hyperemesis, gestational thyrotoxicosis, molar pregnancy
Ductus arteriosus	NSAIDs close it; PGE keeps it open
Oligohydramnios	Renal agenesis, PPROM, FGR, ACE inhibitors — pulmonary hypoplasia
Polyhydramnios	Diabetes, oesophageal or duodenal atresia — PPH, cord prolapse
Cardiac output +30–50%, SVR down	BP falls mid-pregnancy; heart disease decompensates
Aortocaval compression after 20 weeks	Left lateral tilt; manual uterine displacement in arrest
PaCO2 about 4 kPa	Normal PaCO2 in acute asthma is dangerous
FRC down, O2 use up	Rapid desaturation; difficult airway
GFR +50%, creatinine low	"Normal" creatinine may be abnormal
Hypercoagulable	VTE — highest postpartum; LMWH
ALP up, ALT should be normal	Raised transaminases are abnormal
Valproate	Pregnancy prevention programme
ACE inhibitors, warfarin, statins, methotrexate	Stop before or in early pregnancy

Spot the Diagnosis

Clue	Explanation
Hb 106 g/L at 30 weeks with normal ferritin	Physiological dilutional anaemia
Creatinine 95 µmol/L at 28 weeks	Abnormal for pregnancy — investigate kidney function
ALP 3 times normal at 34 weeks, other LFTs normal	Placental ALP — normal
ALT 180 with itching of palms and soles at 32 weeks	Intrahepatic cholestasis of pregnancy
Soft ejection systolic murmur at 24 weeks	Physiological flow murmur
Diastolic murmur and breathlessness at 28 weeks	Mitral stenosis — echo
Dizziness lying flat at 34 weeks	Supine hypotension (aortocaval compression)
PaCO2 5.4 kPa in a pregnant woman with severe asthma	Life-threatening — tiring
Low TSH with mild symptoms and severe vomiting at 10 weeks	Gestational transient thyrotoxicosis (hCG)
Very high hCG, vomiting and "snowstorm" scan	Molar pregnancy
Glycosuria at booking with normal glucose	Physiological — reduced renal threshold
Severe oligohydramnios and absent bladder on scan	Bilateral renal agenesis
Polyhydramnios and "double bubble" on scan	Duodenal atresia (Down syndrome association)
Oligohydramnios in a woman who kept taking lisinopril	ACE inhibitor fetopathy
Failure of lactation and amenorrhoea after massive PPH	Sheehan's syndrome
Brow presentation in established labour at term	Caesarean section
Lost reflexes and slow breathing on magnesium sulfate	Magnesium toxicity — calcium gluconate
Bronchospasm after a PPH drug in an asthmatic	Carboprost
Severe hypertension after Syntometrine	Ergometrine
Drowsy breastfed baby with apnoea; mother on codeine	Infant opioid toxicity
Neural tube defect in a woman with epilepsy	Valproate exposure
Baby with nasal hypoplasia and stippled epiphyses	Warfarin embryopathy
Hyperthyroid woman planning pregnancy on carbimazole	Switch to propylthiouracil for the first trimester

Exam-style Scenarios

1. A 32-year-old woman at 30 weeks has acute severe asthma. Her ABG shows pH 7.38, PaCO₂ 5.3 kPa, PaO₂ 9.0 kPa on oxygen.
Answer: Life-threatening asthma — the "normal" PaCO₂ is high for pregnancy.

• Normal PaCO₂ in pregnancy is about 4 kPa — 5.3 kPa means she is tiring.
• Treat as for non-pregnant asthma — oxygen (target 94–98%), nebulised salbutamol and ipratropium, steroids, IV magnesium; early critical care and anaesthetic review.
• Left lateral tilt; fetal monitoring once stable; obstetric team.

2. A 28-year-old woman with hypertension on ramipril and atorvastatin wants to become pregnant.
Answer: Pre-conception medication review.

• Switch ramipril to labetalol or nifedipine (ACE inhibitors cause fetal renal damage after the first trimester).
• Stop the statin before conception.
• Folic acid; aspirin 75–150 mg from 12 weeks (chronic hypertension — pre-eclampsia risk); BP target and home monitoring.

3. A woman has a PPH of 1,800 mL after a vaginal birth. She has severe pre-eclampsia and asthma. Oxytocin has been given.
Answer: Ongoing PPH — choose drugs carefully.

• Call for help, uterine massage, IV access, bloods (including fibrinogen), major haemorrhage protocol.
• Tranexamic acid 1 g IV; oxytocin infusion; misoprostol.
• Avoid ergometrine (pre-eclampsia) and carboprost (asthma); examine for tears and retained tissue; theatre (balloon tamponade, surgery or embolisation) if bleeding continues.

4. A woman with epilepsy on sodium valproate is 6 weeks pregnant. She is seizure-free.
Answer: Urgent specialist review — don't stop valproate abruptly.

• Urgent neurology and obstetric medicine review — discuss switching (e.g. to lamotrigine or levetiracetam) — abrupt withdrawal risks seizures and SUDEP.
• Folic acid 5 mg; detailed anomaly scanning; counselling on neurodevelopmental risk.
• Report via the pregnancy registers; review why the pregnancy prevention programme failed.

5. A woman at 31 weeks has threatened preterm labour with contractions and cervical change.
Answer: Prepare for preterm birth.

• Antenatal corticosteroids (betamethasone or dexamethasone — 2 IM doses).
• Magnesium sulfate for fetal neuroprotection (if birth expected within 24 hours — recommended under 30 weeks, consider 30–34).
• Tocolysis (nifedipine or atosiban) to allow steroids and transfer to a unit with a suitable neonatal service; GBS prophylaxis per protocol.

Key Points

• Uterine blood flow is 500–750 mL/min at term — PPH is controlled by myometrial contraction.
• The pelvic inlet is widest transversely and the outlet widest AP; station is measured from the ischial spines.
• Well-flexed vertex presents 9.5 cm; brow presents 13.5 cm and can't deliver.
• Failed spiral artery remodelling underlies pre-eclampsia and FGR.
• IgG crosses the placenta — protective and harmful antibodies; heparin and insulin don't cross.
• hCG peaks at 8–12 weeks; hPL causes insulin resistance; progesterone relaxes smooth muscle.
• Fetal shunts — ductus venosus, foramen ovale, ductus arteriosus.
• Cardiac output rises 30–50%, SVR and BP fall mid-pregnancy; aortocaval compression after 20 weeks.
• Compensated respiratory alkalosis — PaCO₂ about 4 kPa; rapid desaturation.
• GFR up 50% — low creatinine; glycosuria normal; PCR over 30 mg/mmol significant.
• Hypercoagulable — VTE risk highest postpartum; D-dimer unhelpful.
• ALP rises, transaminases shouldn't; TSH falls in the first trimester; increase levothyroxine.
• Teratogens — valproate, warfarin, ACE inhibitors, methotrexate, mycophenolate, isotretinoin, lithium, carbimazole (first trimester).
• Uterotonics — no ergometrine in hypertension, no carboprost in asthma; tranexamic acid early.
• Most drugs are compatible with breastfeeding — avoid codeine and tramadol.

Guidelines and Further Reading

• NICE NG201: Antenatal care; NICE NG235: Intrapartum care (2023); NICE NG194: Postnatal care
• NICE NG133: Hypertension in pregnancy; NICE NG3: Diabetes in pregnancy; NICE NG25: Preterm labour and birth
• RCOG Green-top Guidelines: 37a and 37b (VTE in pregnancy), 52 (postpartum haemorrhage), 69 (nausea and vomiting and hyperemesis), 29 (perineal tears)
• British Society for Haematology: Iron deficiency in pregnancy
• UK Teratology Information Service (UKTIS) and "best use of medicines in pregnancy" (bumps)
• Specialist Pharmacy Service: Medicines in breastfeeding (UKDILAS)
• MHRA: Valproate and topiramate pregnancy prevention programmes; codeine in breastfeeding
• MBRRACE-UK: Saving Lives, Improving Mothers' Care (maternal death reports)
• BNF — for current doses