GC115 I Am Pregnant Medical Problems Complicating Pregnancy
Pre-existing or newly arising medical conditions—such as hypertension, diabetes, thyroid disorders, cardiac disease, or thromboembolic disease—that complicate pregnancy and require specialized management to optimize maternal and fetal outcomes.
Medical Problems Complicating Pregnancy
This lecture (GC 115) uses a case-based framework to teach the principles of managing medical diseases that coexist with, arise from, or are worsened by pregnancy. It is not about memorizing the management of every single medical disease in detail — rather, it is about learning a systematic thinking framework that you can apply to any medical condition in a pregnant woman. [1]
The overarching theme is a four-way interaction:
- Effect of pregnancy on the disease (and its natural history)
- Effect of the disease on the pregnancy (mother and fetus)
- Effect of the disease's treatment on the pregnancy
- Effect of the pregnancy on the disease's treatment (pharmacokinetics, teratogenicity, need to change drugs)
The lecture explicitly states the concluding principle: "Treat the patient, not the disease." [1]
Learning Objectives (from Theme Case 1) [2]
- Describe the pathophysiology of a pre-existing medical disorder in pregnancy
- Describe effects of a pre-existing medical disorder on pregnancy (and vice versa)
- Describe principles of management: pre-pregnancy → antepartum → intrapartum → postpartum
- Recognize the concept of multidisciplinary approach and combined medical-obstetrics clinics
- Awareness of pre-pregnancy counselling
- Provide appropriate counselling, triage into low/high risk, and refer to tertiary centres
Three categories are explicitly listed on the lecture slide and are a very common exam stem: [1]
| Category | Examples | Why it matters |
|---|---|---|
| 1. Co-incidental / Pre-existing | DM, renal disease, pre-existing HTN, autoimmune diseases, cardiac diseases, asthma | Disease was there before pregnancy; pregnancy may worsen it or it may worsen pregnancy |
| 2. Arising as a result of pregnancy | Hyperemesis gravidarum, gestational HTN, gestational DM, acute fatty liver of pregnancy, acute renal failure or DIC secondary to obstetric complications | These conditions would not exist without the pregnancy; they resolve after delivery |
| 3. Pregnancy increases risk or aggravates | Iron deficiency anaemia, thromboembolism | Physiological changes of pregnancy (↑ plasma volume, hypercoagulability) predispose to these |
Why this classification matters
This is the lecture's scaffolding. Every case in the lecture maps onto one or more of these categories. The exam frequently asks you to classify a given condition. Understanding why each condition falls where it does requires understanding normal pregnancy physiology (↑ cardiac output ~40%, ↑ blood volume ~50%, ↑ clotting factors, relative insulin resistance from placental hormones, immune modulation).
Case 1: Hypertension in Pregnancy (Mary)
- 26-year-old domestic helper, concealed pregnancy, no antenatal care
- Presents with headache, nausea, vomiting; BP 180/100 mmHg, oedematous, urine albustix +++, fetal movement palpable [1]
This classification is directly from the lecture slides and is extremely high yield: [1]
| Type | Definition | Key Feature |
|---|---|---|
| Pre-existing hypertension | High BP before 20 weeks | Already hypertensive before pregnancy |
| Pre-existing renal disease | Proteinuria before 20 weeks (after excluding UTI) | Kidney disease causing proteinuria |
| Gestational hypertension | Normal BP before 20 weeks, high BP first detected after 20 weeks, without proteinuria or other features of pre-eclampsia | New-onset HTN of pregnancy without maternal organ or uteroplacental dysfunction |
| Pre-eclampsia | New hypertension after 20 weeks plus proteinuria or new maternal organ/uteroplacental dysfunction | A multisystem placental disease; proteinuria is not mandatory |
| Pre-existing + superimposed pre-eclampsia | Chronic hypertension with new features of pre-eclampsia after 20 weeks | Diagnose from the whole clinical picture, not proteinuria alone |
Why 20 weeks is the cut-off: The pathophysiology of pre-eclampsia involves abnormal trophoblast invasion of spiral arteries, which occurs in the first and early second trimester. Clinical manifestations usually appear after 20 weeks. Hypertension detected earlier should prompt evaluation for chronic hypertension or another cause, although rare exceptions exist.
Current diagnostic update
The 2023 slide deck uses the older shorthand “hypertension + proteinuria.” Current NICE criteria also diagnose pre-eclampsia when new hypertension after 20 weeks coexists with renal, hepatic, neurological, haematological, or uteroplacental dysfunction—even without proteinuria. Severe hypertension is over 160 systolic or over 110 diastolic mmHg. [9]
In Mary's case, she is "unclassified" because she had no antenatal care — could be any of the above. However, her symptoms are suggestive of pre-eclampsia. [1]
The lecture explicitly lists these complications: [1]
| System | Manifestations |
|---|---|
| Renal | Renal insufficiency |
| Hepatic | Liver derangement |
| Neurological | Eclampsia, altered mental status, blindness, visual scotomata, stroke, clonus, new-onset severe headaches not responsive to medication |
| Haematological | Thrombocytopenia, DIC, haemolysis (→ HELLP syndrome) |
| Uteroplacental | Fetal growth restriction, abnormal umbilical artery Doppler, stillbirth |
Why these organs are affected: Pre-eclampsia is fundamentally an endothelial disease. Abnormal placentation → release of anti-angiogenic factors (sFlt-1) → widespread maternal endothelial dysfunction → vasospasm, increased permeability, platelet activation → damage to kidneys (glomerular endotheliosis), liver (periportal necrosis), brain (vasogenic oedema), and the coagulation system.
"Should drugs be given to lower her blood pressure? Yes — irrespective of the cause of hypertension, severe hypertension should be controlled to prevent intracerebral haemorrhage." [1]
| Point | Detail |
|---|---|
| Drug choice | Use a pregnancy-specific protocol; do not infer that every drug other than an ACE inhibitor is safe |
| Dose caution | Titrate and monitor closely in an obstetric high-dependency setting when severe |
| Avoid overshoot | Treat urgently, while avoiding hypotension that could compromise uteroplacental perfusion |
| Common drugs | Labetalol (IV or PO), hydralazine (IV), nifedipine (PO) |
Why ACEi are contraindicated
ACE inhibitors cross the placenta and decrease fetal renal perfusion → oligohydramnios, renal dysgenesis, skull ossification defects, IUGR, and fetal death. This is a universal contraindication in pregnancy, not just in pre-eclampsia. ARBs are equally contraindicated (same mechanism — blocking RAAS in the fetus). This is a classic exam trap.
For acute severe hypertension, NICE recommends immediate treatment with labetalol, oral nifedipine, or intravenous hydralazine and frequent BP reassessment. For ongoing treatment, labetalol is generally first choice, with nifedipine or methyldopa as alternatives according to contraindications and patient factors. [9]
The lecture explicitly requires these steps: [1]
- Prevention of eclampsia → Magnesium sulphate
- Investigations: CBC, renal function, liver function, coagulation tests
- Monitor fetal wellbeing when mother is stable
- Consider delivery of the baby — definitive treatment of pre-eclampsia is delivery
Why MgSO₄ and not other anticonvulsants? The MAGPIE trial showed that MgSO₄ reduces eclampsia risk by ~58% compared to placebo, and is superior to diazepam or phenytoin. It acts by stabilizing neuronal membranes (blocks NMDA receptors), causes cerebral vasodilation (reducing vasospasm), and has mild antihypertensive effects.
Case 2: Pre-existing Diabetes Mellitus in Pregnancy (Lin)
- 25-year-old clerk, insulin-dependent DM since age 16, poor compliance, recurrent DKA
- Admitted with hypoglycaemia; LMP 10 weeks ago; pregnancy test positive [1]
Three key effects are listed: [1]
| Effect | Mechanism |
|---|---|
| Blood glucose more difficult to control | Fasting hypoglycaemia (fetus siphons glucose continuously) + antagonising effect of placental hormones (hPL, progesterone, cortisol) on insulin → insulin resistance ↑ especially in 2nd/3rd trimester |
| Increased stress on cardiovascular and renal system | ↑ cardiac output, ↑ blood volume, ↑ GFR → kidneys work harder → may worsen diabetic nephropathy |
| Progression of diabetic retinopathy | Rapid improvement in glycaemic control paradoxically worsens retinopathy short-term; also haemodynamic changes in pregnancy |
Maternal aspects: [1]
- ↑ risk of pre-eclampsia
- ↑ risk of UTI (glycosuria provides substrate for bacteria)
- ↑ risk of preterm labour
- ↑ incidence of caesarean section and instrumental delivery (macrosomia, poor labour progress)
Fetal/Neonatal aspects: [1]
This comprehensive list is directly from the lecture slide:
| Complication | Mechanism |
|---|---|
| Congenital malformations (neural tube, skeletal, cardiac, renal, GI) | Hyperglycaemia is teratogenic — disrupts organogenesis in first trimester; incidence directly proportional to HbA1c |
| Preterm delivery | Associated with pre-eclampsia, polyhydramnios, infection |
| Large-for-gestational-age (macrosomia) | Fetal hyperinsulinaemia in response to maternal hyperglycaemia → anabolic hormone drives growth |
| Asphyxia and birth trauma | Macrosomic babies → shoulder dystocia, difficult delivery |
| Metabolic complications | Neonatal hypoglycaemia (baby's pancreas still producing excess insulin after cord is cut) |
| Sepsis | Immunocompromised state in DM |
| Jaundice and phototherapy | Polycythaemia (chronic fetal hypoxia → ↑ EPO) → ↑ RBC breakdown → bilirubin |
| Respiratory complications | Delayed fetal lung maturation (insulin inhibits surfactant production) |
| Long-term consequences (fetal programming) | In-utero exposure to hyperglycaemia → epigenetic changes → ↑ risk of metabolic and cardiovascular diseases in offspring |
"Management starts BEFORE pregnancy" [1]
Pre-pregnancy: [1]
- Good glycaemic control before pregnancy
- Hyperglycaemia is teratogenic
- Incidence of major congenital abnormality is directly proportional to HbA1c level
This is why pre-pregnancy counselling is critical. The critical window for teratogenicity is the first 8 weeks (organogenesis). If you only achieve tight control after discovering pregnancy (often at 6-8 weeks), you may have already missed the window.
During pregnancy: [1]
- Strict glycaemic control
- The slide says oral hypoglycaemics are “not contraindicated,” but this is too broad: metformin is the oral agent with a defined role; other oral glucose-lowering drugs should generally be stopped before pregnancy and replaced with insulin when treatment is needed [10]
- Insulin usually needed
- Monitor for maternal and fetal complications
Multidisciplinary team: [1]
- Endocrinologist — readjust insulin dosage
- Dietitian — individualise carbohydrate distribution, nutritional adequacy, and gestational weight gain; pregnancy does not automatically require “eating for two”
- DM nurse — instruct on day-to-day insulin adjustment, hotline contact
- Detailed fetal ultrasound — exclude congenital abnormalities
Antenatal care: [1]
- Regular follow-up by obstetrician and endocrinologist
- Regular ultrasound for fetal growth
Delivery: [1]
- Lin's labour was induced at 39 weeks in the lecture case; this is not a universal timing rule
- Monitor capillary glucose hourly in labour, aiming for 4–7 mmol/L; consider an IV insulin-dextrose infusion from established labour in women with type 1 diabetes [10]
- Baby: early feeding, regular dextrostix monitoring
Current timing framework: NICE advises planned birth at 37+0 to 38+6 weeks for uncomplicated pre-existing type 1 or type 2 diabetes. For uncomplicated gestational diabetes, advise birth no later than 40+6 weeks. Deliver earlier if maternal, metabolic, or fetal complications require it. [10]
A woman who is not known to be diabetic may have hyperglycaemia first detected during pregnancy. She and her baby face similar problems, often to a milder degree. [1]
Management starts with diet and exercise advice. If targets are not met within 1–2 weeks, NICE recommends metformin; use insulin when metformin is contraindicated, unacceptable, or insufficient, and consider immediate insulin (with or without metformin) when fasting glucose is markedly elevated or complications are present. [10]
Case 3: Thyroid Disease in Pregnancy (Tina)
- 35-year-old with Grave's disease, had RAI at 30, on thyroxine 100mcg daily, poorly compliant
- Pregnant at 12 weeks: TSH 6.8 mU/L, normal FT4, clinically euthyroid [1]
Transient biochemical hyperthyroidism can occur in early pregnancy, especially in women with hyperemesis gravidarum — no clinical features of thyrotoxicosis [1]
Why? hCG shares structural homology with TSH (both are glycoprotein hormones with a common alpha subunit). In early pregnancy, hCG peaks at 10-12 weeks and can weakly stimulate the TSH receptor → ↑ FT4, ↓ TSH. This is physiological and does NOT require treatment. In hyperemesis, hCG levels are even higher, so this effect is more pronounced.
Thyroid disease, especially autoimmune thyroiditis, occurs more frequently in the postpartum period [1]
Why? Pregnancy causes relative immune suppression (to tolerate the semi-allogeneic fetus). Postpartum, the immune system "rebounds" → flare of autoimmune conditions including Hashimoto's thyroiditis and postpartum thyroiditis.
Thyroxine has no known adverse effect on the pregnancy unless clinically hyperthyroid [1]
Subclinical hypothyroidism (high TSH, normal FT4) is associated with preterm labour and increased incidence of delayed neurological development in offspring — but this is observational data only; effectiveness of routine screening and treatment not known yet [1]
Why does maternal hypothyroidism affect the fetus? Maternal thyroid hormone is particularly important before the fetal thyroid is functioning adequately. The slide's statement that routine screening and treatment were “not known yet” reflects its historical framing; in practice, interpret TSH against pregnancy-specific ranges and manage with obstetric/endocrine input rather than withholding treatment solely because FT4 is normal.
The lecture explicitly states: [1]
| Point | Detail |
|---|---|
| RAI contraindicated | Radioactive iodine crosses the placenta → destroys fetal thyroid |
| PTU and carbimazole/methimazole | Both cross the placenta and both require the lowest effective dose; methimazole/carbimazole has a recognised first-trimester embryopathy pattern |
| PTU preference in first trimester | Preferred because methimazole/carbimazole embryopathy is a concern; consider changing to methimazole/carbimazole after the first trimester because PTU can cause severe hepatotoxicity |
| Both can cause neonatal hypothyroidism | Usually reversible |
| Grave's disease autoantibodies | TSH receptor antibodies (TRAb) can cross the placenta → neonatal thyrotoxicosis (rare but important) |
Clinical pearl from Block A Endocrine: [3,11]
- First trimester: use PTU when an antithyroid drug is required
- Second trimester onwards: consider switching to CMZ (PTU has hepatotoxicity risk)
- Use the lowest dose that keeps maternal FT4 high-normal to mildly elevated; avoid block-and-replace therapy
- Always stabilize thyroid function before conception — uncontrolled hyperthyroidism also harms pregnancy
Two explanations for her high TSH: [1]
- Poor compliance to thyroxine replacement
- True subclinical hypothyroidism
Action: Check compliance, reinforce importance of compliance; increase dosage if compliant but TSH still elevated
For women already taking levothyroxine, requirements commonly rise in pregnancy. The ATA advises an immediate 20–30% dose increase when pregnancy is confirmed, followed by prompt thyroid testing and dose adjustment; a TSH of 6.8 mU/L at 12 weeks therefore warrants timely reassessment rather than observation alone. [12]
Case 4: SLE in Pregnancy (Tung)
- 30-year-old with SLE (lupus nephritis at 24), unplanned pregnancy at 27 during flare → rapid renal deterioration → pregnancy terminated
- Now on prednisolone 5mg/day, normal renal function, mild proteinuria 600mg/day, wants to try again [1]
Three fundamental principles from the lecture: [1]
-
Pregnancy is associated with changes in the immune system — some autoimmune diseases may worsen, some may improve during pregnancy
- SLE tends to flare (especially lupus nephritis)
- Rheumatoid arthritis often improves (Th2 shift in pregnancy)
-
Pregnancy may further stress the end-organ/system affected by the autoimmune disease (e.g., kidney)
-
The slide says pregnancy is “contraindicated” during an acute flare. A safer modern formulation is: defer planned conception until disease is quiescent, optimise pregnancy-compatible therapy, and use multidisciplinary counselling; an established pregnancy during a flare requires individualised specialist care, not an automatic outcome. [13]
The lecture explicitly lists these transplacental antibody effects: [1]
| Antibody | Effect on Baby |
|---|---|
| Anti-platelet antibodies (ITP) | Fetal thrombocytopenia |
| Anti-Ro (SSA) and anti-La (SSB) antibodies | Both are associated with neonatal lupus; the most important irreversible manifestation is congenital heart block (particularly anti-Ro, often with anti-La), while rash/cytopenias/liver abnormalities are usually transient |
| Lupus anticoagulant / Anticardiolipin | IUGR and pregnancy loss (antiphospholipid syndrome mechanism — thrombosis of placental vessels) |
2025 Past Paper Alert
The 2025 Fourth Summative MCQ Q76 directly asks: "A fetus has complete heart block on anomaly scan at 20 weeks. What maternal blood test should be performed?" Answer: Anti-Ro antibody [4]. This is a direct application of this lecture slide.
Listed explicitly: [1]
- Autoimmune thyroiditis → hypothyroidism → affects fetal neurological development
- Renal disease + hypertension → IUGR, ↑ superimposed pre-eclampsia
- ITP → excessive bleeding during delivery
From the lecture slides: [1]
| Drug | Risk |
|---|---|
| Glucocorticoids | The slide lists IUGR and cleft lip; current counselling should avoid implying simple causation because disease activity and dose confound these associations. Prednisolone is pregnancy-compatible when indicated; use the lowest effective dose |
| Azathioprine | Relatively safe |
| Methotrexate | Contraindicated in pregnancy (potent teratogen — folate antagonist → neural tube defects, limb defects, craniofacial abnormalities) |
| Other immunosuppressants | Drug-specific review is essential: hydroxychloroquine and azathioprine are generally compatible; methotrexate, mycophenolate, and cyclophosphamide require avoidance/discontinuation before planned conception [13] |
Yes — her disease is well controlled on low-dose steroids. But need to: [1]
- Check antibodies: anti-Ro, lupus anticoagulant, anticardiolipin
- Prepare for small to moderate increased risk of pre-eclampsia, IUGR, pregnancy loss
- Joint management by rheumatologist and obstetrician
Case 5: Cardiac Disease in Pregnancy (Lian)
- 17-year-old student, TOF diagnosed at birth, corrective surgery in childhood
- Good RV function on digoxin, but has pulmonary regurgitation, awaiting pulmonary valve replacement
- On frusemide; unplanned, unwanted pregnancy at 26 weeks [1]
Heart failure can occur during pregnancy in a woman with well-compensated cardiac disease: [1]
| Mechanism | Explanation |
|---|---|
| Physiological ↑ cardiac output | CO increases ~40% by 28-32 weeks — a diseased heart may not cope |
| Antenatal anaemia | Dilutional anaemia → heart needs to work harder |
| Tocolytic drugs | Beta-adrenergics (e.g., ritodrine) for arresting preterm labour → ↑ HR, ↑ CO |
| Stress and physical demand of labour | Each contraction autotransfuses ~500mL blood into circulation |
| Excessive IV fluids | Iatrogenic volume overload |
Postpartum period: decrease in uterine blood volume → increases effective circulatory volume → volume overload → can precipitate heart failure (often RIGHT heart failure) → increase R-to-L shunting especially with pulmonary hypertension [1]
Why the postpartum period is dangerous: Uterine contraction and relief of caval compression shift blood back into the central circulation; mobilised extracellular fluid adds further preload over the following days. A vulnerable heart can decompensate during this early postpartum haemodynamic shift. This is distinct from VTE physiology: VTE risk is highest immediately after birth and remains elevated through the first 6 weeks postpartum. [14]
Fetal size is smaller and preterm labour is more frequent because: [1]
- Normal physiological increase in cardiac output may be limited by the cardiac condition → reduced uteroplacental perfusion
- Hypoxia in cyanotic heart disease → fetal growth restriction
This is a critical slide: [1]
| Drug | Effect on Pregnancy |
|---|---|
| Diuretics | May limit normal physiological volume expansion → IUGR |
| Warfarin | ↑ risk of congenital abnormalities (warfarin embryopathy), fetal loss |
| ACE inhibitors | Fetal loss, oligohydramnios, ↓ fetal renal perfusion |
Warfarin embryopathy: Warfarin crosses the placenta (unlike heparin). It inhibits vitamin K-dependent proteins needed for fetal bone/cartilage development → nasal hypoplasia, stippled epiphyses, chondrodysplasia punctata. Most dangerous in weeks 6-12. After first trimester, the main risk is fetal intracranial haemorrhage (due to anticoagulation of the fetus).
Listed from the lecture: [1]
- Teratogenic drugs may need to be substituted before pregnancy and in the first trimester
- Pharmacokinetic changes in pregnancy affect serum levels of drugs (e.g., digoxin, warfarin — ↑ plasma volume → ↓ drug levels → need dose adjustments)
- Careful readjustment of dosage during pregnancy
- Cardiac catheterization (X-ray exposure), open heart surgery (hypotension, hypothermia, hypoxia) carry high risks during pregnancy
From the lecture: [1]
| Consideration | Detail |
|---|---|
| Antibiotic prophylaxis for endocarditis | The slide's blanket “needed” rule is outdated. Routine prophylaxis is not automatic; ESC 2025 says systemic prophylaxis may be considered for delivery in women at high IE risk (Class IIb, level C), so use Pregnancy Heart Team/local guidance [15] |
| Thromboembolism prevention | Essential in patients with mechanical valves or those at high risk |
| Mode & timing of delivery | Availability of multidisciplinary specialists; in general, spontaneous onset of labour, vaginal delivery ± epidural analgesia carries lowest risks but must be individualized |
The lecture walks through the actual management: [1]
- Joint case conference: obstetricians, paediatric + adult cardiologists, anaesthesiologists
- Continued digoxin and frusemide
- Paediatric cardiologist assessed every 4 weeks → every 2 weeks from 32 weeks
- Frusemide increased at 32 weeks for progressive SOB
- Fetal growth monitored every 4 weeks → along 10th centile
- Labour induced at 38 weeks with epidural analgesia
- No antibiotics cover needed (no mechanical valve, no grossly damaged valve)
- Normal vaginal delivery, baby boy 2.7kg, healthy
- Barrier contraception was advised in this case. Do not generalise this to all cardiac patients: select contraception according to the lesion, thrombotic risk, drug interactions, efficacy needs, and patient preference with specialist input
- Pulmonary valve replacement to be scheduled after delivery
Case 6: Epilepsy in Pregnancy (Hong)
- 28-year-old, grand mal epilepsy on phenytoin since age 16
- Stopped phenytoin when she found out she was pregnant (worried about teratogenicity)
- Had 3 attacks in one month after stopping [1]
"Many antiepileptic drugs are teratogenic" — cleft lip and palate, neural tube defects [1]
"Should antiepileptic drugs be stopped? If epilepsy cannot be controlled without drugs, DO NOT stop the drugs. Consider monotherapy if possible." [1]
Why not stop? Abrupt withdrawal can precipitate recurrent convulsive seizures or status epilepticus, risking maternal trauma, hypoxia, and fetal compromise. Risk is drug- and dose-specific, so there is no single “AED teratogenicity rate.” Treatment changes should be planned with an epilepsy specialist—ideally before conception—and never made abruptly by the patient. [16]
"Folic acid supplement decreases the incidence of congenital abnormalities associated with antiepileptic drugs" [1]
Why folic acid? Folate is essential during early neural-tube development. Current MHRA advice is folic acid 5 mg/day before any possibility of pregnancy for women taking antiseizure medication. It is recommended risk reduction, but it does not eliminate drug-specific teratogenic risk—particularly with valproate. [16]
Current antiseizure-medication safety update
Lamotrigine and levetiracetam have the most reassuring pregnancy safety data among the commonly reviewed agents; use monotherapy and the lowest effective dose where possible. Valproate is highly teratogenic (about 10% major congenital malformations and 30–40% neurodevelopmental disorders in exposed children) and is subject to strict pregnancy-prevention restrictions. If pregnancy occurs on any antiseizure medication, obtain urgent specialist review—do not stop it abruptly. [16]
"Detailed prenatal ultrasound examination to assess fetal anatomy" [1]
Case 7: Thromboembolism in Pregnancy (Jane)
- 39-year-old smoker, 80kg, threatened miscarriage at 12 weeks, advised bed rest
- Developed mild SOB after one week in bed → given cough remedy
- Collapsed and died at home
- Postmortem: massive pulmonary embolism [1]
Critical Teaching Point
This case illustrates a catastrophic outcome from inappropriately prescribing bed rest. The lecture explicitly teaches: "Do not prescribe bed rest for conditions where this is not proven to be effective — do not prescribe bed rest for threatened miscarriage, IUGR." Bed rest increases VTE risk without proven benefit for these conditions. This is an exam favourite.
Virchow's triad — all three components are present during pregnancy: [1]
| Component | Pregnancy Mechanism |
|---|---|
| Immobility | Relatively less mobile during pregnancy |
| Hypercoagulability | ↑ clotting factors (fibrinogen, VII, VIII, X, vWF), ↓ protein S; further increases postpartum; viscosity may increase in hyperemesis |
| Obstruction to blood flow | Gravid uterus compresses IVC and iliac veins |
Why is the postpartum period highest risk? [5] Hypercoagulability, vascular injury, and immobility combine after delivery, especially following caesarean birth. Risk is greatest just after birth and remains elevated throughout the first 6 weeks postpartum; “highest at 6 weeks” is not the correct interpretation. [14]
The lecture divides risk factors into pre-existing and current: [1]
Pre-existing:
- Advanced age, obesity, ethnicity
- Smoking
- Congenital or acquired thrombophilia
- Personal/family history of thromboembolism
Current (pregnancy and treatment related):
- Pre-eclampsia, hyperemesis, bed rest, caesarean delivery, postpartum genital tract infection
- Concurrent: infection, immobilization due to injury, long-haul flights
Key prevention strategies from the lecture: [1]
| Strategy | Detail |
|---|---|
| Minimize immobility | Do NOT prescribe bed rest for threatened miscarriage, IUGR |
| Adequate hydration | Prevents haemoconcentration |
| Compression stockings | Graduated compression |
| Prophylactic anticoagulation | For women at increased risk during pregnancy and postpartum |
Anticoagulation choices in pregnancy: [1]
| Drug | Notes |
|---|---|
| LMWH / Unfractionated heparin | Drug of choice — does NOT cross placenta [5] |
| Warfarin / other vitamin K antagonists | Cross the placenta. For ordinary pregnancy-associated VTE prevention/treatment, LMWH is preferred antenatally; warfarin is compatible postpartum. A mechanical valve is a separate high-risk exception requiring a specialist regimen [15] |
The following sequential warfarin/LMWH schedule appeared in older Block A material [5], but should not be applied as a generic pregnancy-VTE regimen:
- Warfarin crosses placenta → risk of fetal ICH and teratogenicity
- Mechanical-valve anticoagulation must balance fetal VKA harm against valve thrombosis. ESC 2025 supports continuing a VKA in the second/third trimesters to 36 weeks for higher valve-thrombosis risk, or twice-daily therapeutic LMWH with anti-Xa monitoring for selected lower-risk patients; LMWH without anti-Xa monitoring is not recommended [15]
- Peripartum conversion and restart require a written multidisciplinary plan; do not use a universal “switch at 36 weeks” answer without specifying indication and risk
- Postpartum prophylaxis duration is risk-stratified; 6 weeks is used for previous VTE and several high-risk categories, not every pregnant patient [14]
- Use pre-pregnancy weight for dose calculation
This is the systematic thinking approach the lecture teaches: [1]
For ANY medical condition in pregnancy, ask four questions:
The final summary slide lists the overarching principles: [1]
- Obstetric conditions can mimic medical conditions (e.g., pre-eclampsia mimicking hypertensive encephalopathy)
- Women with chronic medical diseases can get pregnant → pre-pregnancy counselling, contraceptive advice, careful drug use
- Effects of pregnancy on pre-existing medical disease AND its treatment
- Effects of medical disease AND its treatment on pregnancy
- Consider BOTH mother and baby
- Prevalence of some medical diseases increases during pregnancy or postpartum (e.g., VTE)
| Drug | Safe in Pregnancy? | Notes |
|---|---|---|
| Labetalol | ✅ Yes | First-line antihypertensive in pregnancy |
| Nifedipine | ✅ Yes | Second-line; calcium channel blocker |
| Hydralazine | ✅ Yes | IV for acute severe HTN |
| MgSO₄ | ✅ Yes | Eclampsia prevention/treatment |
| Insulin | ✅ Yes | Mainstay for DM control in pregnancy |
| Metformin | ⚠️ Conditional | Defined role in pre-existing type 2 diabetes and GDM; individualise [10] |
| Other oral glucose-lowering drugs | ❌ Generally avoid | Stop before pregnancy and use insulin instead unless specialist guidance says otherwise [10] |
| Thyroxine | ✅ Yes | No adverse effects unless clinically hyperthyroid |
| PTU | ⚠️ Preferred when treatment is needed in 1st trimester | Both PTU and carbimazole/methimazole cross placenta; PTU carries serious hepatotoxicity risk [11] |
| Carbimazole / methimazole | ⚠️ Usually preferred after 1st trimester | Recognised first-trimester embryopathy pattern; use lowest effective dose [11] |
| Prednisolone | ✅ Compatible when indicated | Use the lowest effective dose; avoid attributing confounded fetal associations to the drug alone [13] |
| Azathioprine | ✅ Relatively safe | Can continue if needed |
| LMWH / Heparin | ✅ Yes | Does not cross placenta |
| Folic acid | ✅ Yes | Essential; high dose (5mg) with AEDs |
| Digoxin | ✅ Yes | May need dose adjustment |
| ACE inhibitors | ❌ Contraindicated | Oligohydramnios, renal dysgenesis, fetal death |
| ARBs | ❌ Contraindicated | Same mechanism as ACEi |
| Warfarin | ⚠️ Specialist indication only antenatally | Crosses placenta; mechanical-valve regimens are individualised. Compatible postpartum [15] |
| Methotrexate | ❌ Contraindicated | Potent teratogen |
| Radioactive iodine | ❌ Contraindicated | Destroys fetal thyroid |
| Valproate | ❌ Avoid unless no effective/tolerated alternative | About 10% major congenital malformations and 30–40% neurodevelopmental disorders; strict pregnancy-prevention restrictions apply [16] |
Exam Intelligence
- Classification questions: "Classify hypertensive disorders of pregnancy" — know the 20-week cut-off
- Drug safety: "Which drugs should be avoided?" — ACEi/ARBs, MTX, RAI; warfarin is not a simple trimester mnemonic because mechanical-valve anticoagulation is a specialist exception
- Clinical scenarios: Case vignette → identify the four-way interaction
- Investigation interpretation: Pre-eclampsia workup (CBC, RFT, LFT, coagulation)
- Antibody-related fetal effects: Anti-Ro → congenital heart block (2025 MCQ Q76)
- VTE risk: Why pregnancy is a hypercoagulable state; why bed rest is dangerous
| Year | Question | Theme |
|---|---|---|
| 2021 SAQ Q1 | Pre-eclampsia at 39 weeks | Diagnosis, investigations, antihypertensives, eclampsia management [6] |
| 2022 MCQ Q13 | Post-LSCS DVT | VTE risk factors post-delivery [7] |
| 2025 MCQ Q76 | Fetal complete heart block | Anti-Ro antibody [4] |
| 2023 SAQ Q2 | Supine hypotension at 28 weeks | IVC compression by gravid uterus [8] |
Exam Traps to Avoid
- Confusing gestational HTN with pre-eclampsia: Gestational HTN has NO proteinuria; pre-eclampsia = gestational HTN + proteinuria (or other end-organ involvement)
- Thinking all AEDs should be stopped in pregnancy: Uncontrolled seizures are MORE dangerous than drug teratogenicity
- Prescribing bed rest for threatened miscarriage: No proven benefit; increases VTE risk
- Using ACEi in pregnancy: Never — even if the mother has diabetic nephropathy or heart failure
- Forgetting the postpartum period: Many conditions flare or present postpartum (thyroiditis, VTE, heart failure)
- Treating “oral hypoglycaemics” as one class: metformin has a defined role; most other oral agents are stopped and insulin used instead [10]
High Yield Summary
-
Core Framework
- For any medical condition in pregnancy, systematically consider: (1) Effect of pregnancy on disease, (2) Effect of disease on pregnancy, (3) Effect of treatment on pregnancy, (4) Effect of pregnancy on treatment.
- Always consider BOTH mother and fetus.
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Hypertension
- Classify by the 20-week cut-off. Pre-eclampsia = new HTN after 20 weeks plus proteinuria or maternal organ/uteroplacental dysfunction. Treat severe HTN urgently. Use MgSO₄ for eclampsia prevention/treatment. ACEi/ARBs are contraindicated. Delivery is definitive, but timing depends on maternal/fetal status and gestation.
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DM
- Hyperglycaemia is teratogenic (risk rises with HbA1c). Optimise control before pregnancy. Fetal risks include malformations, macrosomia, neonatal hypoglycaemia, respiratory morbidity, and jaundice. Use a multidisciplinary team; birth timing is diabetes-type and complication specific—not a universal 39-week induction.
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Thyroid
- Gestational transient thyrotoxicosis can reflect the hCG effect. RAI is contraindicated. If antithyroid treatment is required, PTU is preferred in the 1st trimester and a switch to carbimazole/methimazole is considered thereafter. Known hypothyroidism usually needs an early levothyroxine dose increase and close TSH monitoring.
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Autoimmune/SLE
- Plan conception during quiescent disease. Anti-Ro/SSA and anti-La/SSB can cause neonatal lupus and congenital heart block; antiphospholipid antibodies increase thrombosis and pregnancy morbidity. Hydroxychloroquine/azathioprine are generally compatible; methotrexate is contraindicated.
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Cardiac
- Pregnancy ↑ CO by 40% → may precipitate heart failure. Postpartum autotransfusion is dangerous. Warfarin teratogenic in 1st trimester. Spontaneous vaginal delivery with epidural is generally safest.
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Epilepsy
- Do NOT stop antiseizure medication abruptly. Obtain specialist review, use monotherapy/lowest effective dose where possible, prescribe folic acid 5 mg/day preconception, and arrange detailed fetal assessment. Valproate has major regulatory restrictions.
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VTE
- All components of Virchow's triad are present in pregnancy. Do NOT prescribe ineffective bed rest. LMWH is the antenatal anticoagulant of choice. VTE risk is highest just after birth and remains elevated through 6 weeks postpartum.
Active Recall - Medical Problems Complicating Pregnancy
[1] Lecture slides: GC 115. I am pregnant medical problems complicating pregnancy.pdf [2] Lecture slides: Block C - O&G Theme Case 1.docx.pdf (Learning Objectives) [3] Senior notes: Block A - I am losing weight and sweating all the time_ causes of severe, weight loss; thyrotoxicosis; hypothyroidism.pdf (PTU/CMZ in pregnancy) [4] Past papers: 2025 Fourth Summative MCQ.pdf (Q76 — anti-Ro antibody and congenital heart block) [5] Senior notes: Block A - Leg swelling and chest pain_ deep vein thrombosis; pulmonary embolism; Thrombophilia.pdf (Pregnancy-related VTE management) [6] Past papers: 2021 Fourth Summative SAQ.pdf (Q1 — pre-eclampsia management) [7] Past papers: 2022 Fourth Summative MCQ.pdf (Q13 — post-LSCS DVT) [8] Past papers: 2023 Fourth Summative SAQ.pdf (Q2 — supine hypotension in pregnancy) [9] NICE. Hypertension in pregnancy: diagnosis and management (NG133), updated 2023. https://www.nice.org.uk/guidance/ng133/chapter/recommendations [10] NICE. Diabetes in pregnancy: management from preconception to the postnatal period (NG3), updated 2025. https://www.nice.org.uk/guidance/ng3/chapter/recommendations [11] American Thyroid Association. Hyperthyroidism in Pregnancy. https://www.thyroid.org/hyperthyroidism-in-pregnancy/ [12] American Thyroid Association. Hypothyroidism in Pregnancy. https://www.thyroid.org/hypothyroidism-in-pregnancy/ [13] EULAR. Recommendations for women's health and family planning in SLE and/or antiphospholipid syndrome. Ann Rheum Dis. 2017;76:476–485. https://ard.bmj.com/content/76/3/476 [14] RCOG. Reducing the Risk of Thrombosis and Embolism during Pregnancy and the Puerperium (Green-top Guideline 37a), amended 2023. https://www.rcog.org.uk/media/m4mbpjwi/gtg-no37a-2015_amended-2023.pdf [15] ESC. 2025 Guidelines for the management of cardiovascular disease and pregnancy. https://www.escardio.org/guidelines/clinical-practice-guidelines/all-esc-practice-guidelines/cardiovascular-diseases-during-pregnancy-management-of/ [16] MHRA. Antiepileptic drugs in pregnancy: updated advice following comprehensive safety review, updated 2024. https://www.gov.uk/drug-safety-update/antiepileptic-drugs-in-pregnancy-updated-advice-following-comprehensive-safety-review
GC114 Climacteric Symptoms Menopause And Related Illness; Amenorrhoea
Climacteric symptoms encompass the vasomotor, psychological, and urogenital manifestations arising from ovarian hormone decline during the menopausal transition, while amenorrhoea refers to the absence of menstruation due to physiological, pathological, or iatrogenic causes.
GC116 I Felt A Lump Below Urinary Incontinence In Females; Genital Prolapse
Urinary incontinence in females is the involuntary loss of urine, and genital prolapse is the descent of pelvic organs (such as the uterus, bladder, or rectum) through the vaginal canal due to weakened pelvic floor support.