Obstetrics and Gynaecology — Medical Disorders in Pregnancy, NMC MBBS licence examination syllabus (Nepal Medical Council).
A woman who is breathless, tired and swollen is describing either a normal pregnancy or heart failure, and the words are the same.
Most obstetric teaching concentrates on things that go wrong with the pregnancy itself — bleeding, pre-eclampsia, obstructed labour. But a large share of maternal death comes from a different direction: a woman who was already ill, or who became ill with something that has nothing to do with obstetrics, and whose illness was interpreted as pregnancy.
The organising difficulty of this chapter is that normal pregnancy mimics disease and masks it at the same time. Learning which is which is most of the clinical skill involved.Three physiological changes cause most of the diagnostic trouble.
Plasma volume rises proportionally more than red cell mass. The result is a fall in haemoglobin concentration in a completely normal pregnancy — a dilution rather than a deficiency. So the non-pregnant threshold for anaemia does not apply, and using it labels healthy women as anaemic while potentially reassuring about women who are genuinely depleted.
Cardiac output, heart rate and blood volume all rise. Breathlessness, ankle swelling, palpitations and a soft flow murmur are all features of normal pregnancy — and all features of heart failure. The symptoms alone cannot separate them.
A healthy young woman compensates extremely well, until she does not. This is the same trap met in obstetric haemorrhage: observations remain reassuring while a large physiological reserve is quietly consumed, and then decompensation is abrupt.
Anaemia in pregnancy is very common, and it is easy to treat as a number to be corrected rather than a problem with consequences. The consequence that matters is this:
Anaemia removes the reserve a woman needs at delivery. Every woman loses blood when she delivers. A woman with a normal haemoglobin tolerates that comfortably; an anaemic woman may not tolerate the same volume at all. A postpartum haemorrhage that would have been survivable becomes fatal — and in settings where blood is not immediately available, that margin is the difference between an ordinary delivery and a maternal death.
Iron deficiency is the commonest cause, but stopping there is a mistake. Consider hookworm, malaria, thalassaemia and other haemoglobinopathies, and B12 or folate deficiency, according to the setting and the blood film.
Treat early, because time is the resource that runs out. Oral iron takes weeks to raise the haemoglobin meaningfully. Anaemia identified at booking can be corrected; the same anaemia identified at term cannot, and the woman goes into labour without the reserve she needs. This is the whole argument for checking early and rechecking.One mechanism explains every complication, so learn the mechanism rather than the list.
Glucose crosses the placenta; insulin does not. Maternal hyperglycaemia therefore delivers a high glucose load to the fetus, which responds by producing its own insulin. Fetal insulin is a growth factor, so the fetus grows and lays down fat.
From that single fact:
Gestational diabetes usually resolves after delivery, but it identifies a woman whose glucose handling is marginal, and it predicts a substantially raised risk of type 2 diabetes later — so postnatal follow-up is part of the management, not an optional extra.
Pregnancy is a sustained cardiovascular stress test lasting months. A heart that copes adequately with ordinary life may fail when asked to sustain a substantially increased output — and the woman may not know she has valve disease until pregnancy reveals it.
The timing of risk is not intuitive. The most dangerous period is labour and the immediate postpartum, because delivery of the placenta returns a large volume of blood to the maternal circulation abruptly. A heart that managed the gradual increase of pregnancy can be overwhelmed by that sudden shift.
In many settings, including much of South Asia, rheumatic heart disease remains the commonest underlying cause. So ask about childhood rheumatic fever, sore throats with joint pains, and any previous diagnosis of a heart murmur.
The distinguishing features that separate pathological breathlessness from the normal breathlessness of pregnancy are worth memorising: breathlessness lying flat, breathlessness waking her at night, chest pain, syncope, or a murmur that is loud, diastolic, or accompanied by any of these. Normal pregnancy does not cause orthopnoea.Three further groups are covered in detail in their own chapters; what matters here is the pregnancy-specific reasoning.
Epilepsy. The central tension is that some antiepileptic drugs carry teratogenic risk, while uncontrolled seizures endanger both mother and fetus — a seizure causes hypoxia, and status epilepticus is life-threatening. The answer is neither to continue blindly nor to stop reflexively, but to review the regimen before conception where possible.
Thyroid disease. Maternal thyroid hormone matters for fetal neurodevelopment, particularly early, and requirements change during pregnancy. Untreated disease has consequences for both; this is a case where treatment is clearly safer than non-treatment.
Infection. Several infections behave differently or worse in pregnancy, and some are transmitted to the fetus. Malaria in pregnancy, hepatitis B, HIV and syphilis all have specific antenatal implications, and screening exists precisely because treatment of an asymptomatic woman prevents transmission — the case of syphilis is set out in the sexually transmitted infections chapter.
Almost everything in this chapter works better before conception than after it, for one reason: organogenesis is largely complete before many women realise they are pregnant, and certainly before many attend their first antenatal visit.
Glucose control at the time of conception, a drug review that switches a teratogenic agent for a safer one, folate supplementation, and optimisation of thyroid or cardiac disease — all of these act in a window that has usually closed by the booking appointment.
So the practical instruction is simple: ask every woman of childbearing age with a chronic illness whether she is planning a pregnancy, and if she might be, review her treatment now rather than later.
And the reverse error is equally important, and covered fully in the prescribing chapter: do not stop treatment reflexively when a woman turns out to be pregnant. Uncontrolled epilepsy, asthma, diabetes, thyroid disease and infection all endanger the fetus. The decision is a weighing of two risks, not an automatic withdrawal.
No glucose or haemoglobin thresholds, drug doses or gestational ages appear here. Gestational diabetes criteria differ between major guidelines, and haemoglobin thresholds in pregnancy differ from non-pregnant values — use your national guideline.
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