Pregnancy, breastfeeding & contraception flashcards
24 high-yield MRCP Part 1 cards from the Intellect Medicos Clinical Pharmacology & Toxicology course. Try to answer each question before you open it — then study them properly with spaced repetition, which brings each card back just before you would forget it.
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Why are ACE inhibitors and ARBs contraindicated in pregnancy?
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They cause fetal renal failure with oligohydramnios (and skull ossification defects), mainly in the 2nd and 3rd trimesters.
Why? The fetal kidney depends on angiotensin II; oligohydramnios then causes limb contractures and pulmonary hypoplasia.
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What is the first-line antihypertensive for chronic or gestational hypertension in pregnancy?
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Labetalol.
Why? NICE recommends labetalol first, then nifedipine; methyldopa is an alternative if these are unsuitable.
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Which cardiac anomaly is associated with lithium exposure in the first trimester?
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Ebstein's anomaly (apical displacement of the tricuspid valve).
Why? The absolute risk is small, so lithium may be continued in pregnancy after specialist discussion, with extra monitoring.
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What fetal harm do aminoglycosides such as gentamicin cause in pregnancy?
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Fetal ototoxicity (damage to the 8th cranial nerve, causing deafness).
Why? Aminoglycosides cross the placenta and damage the developing cochlea and vestibular system.
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Why are tetracyclines avoided in pregnancy and in children under 12?
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They deposit in growing teeth and bone, causing tooth discolouration and impaired bone growth.
Why? Tetracyclines chelate calcium in developing teeth and bones.
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Why are NSAIDs avoided in the third trimester?
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They can cause premature closure of the fetal ductus arteriosus (and oligohydramnios).
Why? Prostaglandins keep the ductus open; NSAIDs block prostaglandin synthesis.
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A woman taking warfarin after a previous DVT finds she is pregnant. Which anticoagulant should she be switched to?
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Therapeutic low molecular weight heparin.
Why? Warfarin crosses the placenta and causes warfarin embryopathy (nasal hypoplasia, stippled epiphyses) in the first trimester and fetal bleeding later. LMWH does not cross the placenta.
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Which antithyroid drug is preferred in the first trimester of pregnancy?
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Propylthiouracil.
Why? Carbimazole in early pregnancy is linked to congenital defects (e.g. aplasia cutis, choanal atresia); many switch to carbimazole after the first trimester because PTU can cause liver injury.
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Under what conditions does the MHRA allow sodium valproate to be prescribed to a girl or woman who could become pregnant?
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It should be used only if other treatments are ineffective or not tolerated, and only within a Pregnancy Prevention Programme (highly effective contraception, annual specialist review, signed risk form).
Why? Valproate in pregnancy causes major malformations (e.g. neural tube defects) and neurodevelopmental disorders in a large proportion of exposed children.
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Misoprostol exposure in pregnancy is linked to ______, and thalidomide to phocomelia.
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Moebius syndrome
Why? Both are classic teratogen associations (Moebius = congenital facial and abducens palsy; phocomelia = shortened limbs).
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Misoprostol exposure in pregnancy is linked to Moebius syndrome, and thalidomide to ______.
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phocomelia
Why? Both are classic teratogen associations (Moebius = congenital facial and abducens palsy; phocomelia = shortened limbs).
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Why is trimethoprim avoided in the first trimester?
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It is a folate antagonist, which increases the risk of neural tube defects.
Why? Trimethoprim inhibits dihydrofolate reductase; nitrofurantoin is usually preferred for UTI in early pregnancy (avoid it at term).
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Why should women who are or may become pregnant not handle crushed or broken finasteride tablets?
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Absorbed finasteride can cause abnormal development of the genitalia of a male fetus.
Why? Finasteride blocks 5-alpha-reductase, which converts testosterone to dihydrotestosterone needed for male external genital development.
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Why is aspirin avoided in breastfeeding?
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Risk of Reye's syndrome in the baby.
Why? Salicylate passes into breast milk; Reye's syndrome causes acute encephalopathy and liver failure in children.
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Why is codeine contraindicated in breastfeeding mothers?
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Mothers who are CYP2D6 ultra-rapid metabolisers convert codeine to morphine quickly, which can cause opioid toxicity and respiratory depression in the baby.
Why? Codeine is a prodrug; CYP2D6 activity varies genetically, so morphine exposure is unpredictable.
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Which antibiotic, given to neonates, causes 'grey baby syndrome'?
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Chloramphenicol.
Why? Neonates cannot glucuronidate chloramphenicol well, so it accumulates, causing cyanosis, vomiting and circulatory collapse.
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Which migraine type is an absolute contraindication (UKMEC 4) to the combined pill?
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Migraine with aura.
Why? Oestrogen plus migraine with aura greatly increases the risk of ischaemic stroke.
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In a smoker aged 35 or over, what level of smoking makes the combined pill UKMEC 4?
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15 or more cigarettes a day (fewer than 15 a day is UKMEC 3).
Why? Smoking and age add to the arterial thrombosis risk of oestrogen (MI and stroke).
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Name two cancers whose risk is reduced by the combined pill.
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Ovarian and endometrial cancer (colorectal cancer risk is also lower).
Why? Suppressing ovulation and endometrial proliferation is protective; breast and cervical cancer risk is slightly increased.
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What is the main mechanism of action of the desogestrel progestogen-only pill?
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It inhibits ovulation (it also thickens cervical mucus).
Why? Traditional progestogen-only pills work mainly by thickening cervical mucus; desogestrel reliably suppresses ovulation.
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Which antiseizure drug, also used for migraine prophylaxis, has needed a Pregnancy Prevention Programme in the UK since June 2024?
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Topiramate.
Why? Exposure in pregnancy raises the risk of major malformations, low birth weight and possibly autism, ADHD and intellectual disability. Women who could become pregnant need highly effective contraception, a negative pregnancy test before starting and a signed Risk Awareness Form.
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What extra contraceptive advice does the MHRA give to a woman using an oral contraceptive pill who starts tirzepatide (Mounjaro)?
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Add a barrier method (e.g. condoms) for 4 weeks after starting and for 4 weeks after each dose increase.
Why? Tirzepatide may reduce absorption of oral contraceptives, particularly in people who are overweight or obese. GLP-1 medicines should also be avoided in pregnancy, so effective contraception is needed.
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What contraceptive advice does the MHRA give to men taking sodium valproate?
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As a precaution, use effective contraception (condoms plus contraception by the female partner) during treatment and for 3 months after stopping; do not donate sperm in that time.
Why? A study suggested a possible increase in neurodevelopmental disorders in children fathered by men taking valproate around conception. Three months covers one full sperm cycle without valproate.
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Which oral acne drug requires a Pregnancy Prevention Programme and mental health and sexual function monitoring at every visit?
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Isotretinoin (an oral retinoid).
Why? Isotretinoin is highly teratogenic. The MHRA also requires counselling and monitoring for psychiatric and sexual side effects and a signed Acknowledgement of Risk form.
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