Estimated reading time: 4 minutes
Medical disorders in pregnancy are a high-yield area for exams like NEET SS, INI-CET, and DNB, yet many questions are misunderstood because aspirants focus only on the final answer rather than the reasoning behind it. In this MCQ discussion session, Dr. Aditya Nimbkar breaks down multiple previous-year recall questions, explaining not just what the correct answer is, but why the other options are incorrect.
This blog summarises the key learning points from the session in a structured, exam-oriented format.
1. Magnesium Sulfate for Fetal Neuroprotection
What Is the Optimal Timing?
One of the most frequently asked MCQs revolves around magnesium sulfate (MgSO₄) use for fetal neuroprotection before preterm birth.
Key Concept
Magnesium sulfate is not routinely given to all women in preterm labour. Its use is selective and evidence-based.
Why Magnesium Sulfate?
Magnesium sulfate is preferred in pregnancy over other antiepileptics because of its broad neuroprotective action. It works through multiple mechanisms:
- A – Adenosine potentiation → neuronal relaxation
- B – GABA-B receptor activation → inhibitory neurotransmission
- C – Calcium channel blockade
- D – NMDA receptor inhibition
- E – Glutamate inhibition (reduces excitotoxicity)
Together, these actions reduce neuronal excitability in both the mother and the fetus.
Why Is This Important for Preterm Babies?
Extremely preterm neonates are prone to:
- Electrolyte imbalances
- Germinal matrix hemorrhage
- Neonatal seizures
Each seizure episode increases the risk of hypoxic brain injury, which magnesium sulfate helps prevent.
Exam-Oriented Answer
- Indication: Imminent preterm birth
- Gestational age: Up to 32 weeks (as per NICE guidelines)
- Minimum duration: At least 4 hours before delivery
- Maximum duration: 24 hours only
Repeat or rescue courses are not recommended.
Dose (Similar to Zuspan Regimen)
- Loading dose: 4 g IV
- Maintenance: 1 g/hour IV infusion
- No intramuscular injections
Why Not Give It Repeatedly?
Excess magnesium:
- Displaces calcium from receptors
- Can cause fetal osteopenia
- May lead to neonatal respiratory depression
Hence, one single course is sufficient.
2. Safest Antipsychotic Drug in Pregnancy (ACOG)
Psychiatric disorders like schizophrenia are not uncommon in pregnancy, making this a high-yield MCQ area.
Neonatal Adaptation Syndrome – A Must-Know Concept
Antipsychotic drugs can cause:
- Poor neonatal tone
- Poor feeding
- Jitteriness
- Extrapyramidal symptoms
- Respiratory distress
This constellation is known as Neonatal Adaptation Syndrome.
Safest Antipsychotic Drugs
According to ACOG and RCOG:
Safest option:
- Haloperidol (best safety data)
Other acceptable options:
- Chlorpromazine
- Olanzapine
- Quetiapine
- Risperidone
Important Clinical Pearl
Second-generation antipsychotics like olanzapine and quetiapine can worsen insulin resistance, increasing the risk of gestational diabetes mellitus (GDM).
What to do?
- Perform OGTT at 24–28 weeks
- Repeat OGTT at 32–36 weeks
Drugs to Avoid
- Clozapine
- Lithium
Breastfeeding Tip (Very Exam-Relevant)
- Peak drug levels occur 1–2 hours after dosing
- Advise mothers to avoid breastfeeding for 2–3 hours after taking the drug
This simple dose-spacing reduces neonatal side effects.
3. CNS Disorder That Worsens During Pregnancy
Trick in the Question
The worsening is not due to hormones, but due to immunological changes.
Immunological Shift in Pregnancy
- Th1 → Th2 dominance
- Increased humoral immunity
- Reduced cell-mediated immunity
Correct Answer: Myasthenia Gravis
- Antibody-mediated disease
- Pregnancy increases antibody production
- Leads to worsening neuromuscular weakness
Why Not the Others?
- Multiple Sclerosis: Cell-mediated → fewer relapses in pregnancy
- Parkinson’s Disease: Symptoms may worsen due to drug dilution but improve with dose adjustment
- Epilepsy: Unpredictable (40% improve, 30% worsen, 30% unchanged)
4. GI Disorder That Does Not Worsen in Pregnancy
Progesterone relaxes smooth muscles and sphincters, leading to:
- GERD (↓ LES tone)
- Constipation (↓ peristalsis)
- Gallstones (biliary stasis)
Correct Answer: Inflammatory Bowel Disease (IBD)
- Ulcerative colitis
- Crohn’s disease
These do not worsen physiologically during pregnancy.
Management of IBD in Pregnancy – High-Yield Points
Safe Drugs
- Sulfasalazine (5-ASA)
- Corticosteroids
- Allopurinol
- Anti-TNF agents (Infliximab, Adalimumab) → only till 24 weeks
Sulfasalazine causes folate trapping → Give 5 mg folic acid daily
Drugs to Avoid
- Methotrexate
- Tofacitinib
Methotrexate remains in tissues for months — avoid conception for at least 6 months
Crohn’s Disease and Mode of Delivery
- Perianal Crohn’s disease → No episiotomy
- Risk of deep perineal tears
- Elective Caesarean Section is preferred
Key Takeaway for Exams
This session reinforces one crucial rule for medical exams:
Understanding the “why” behind an answer is more important than memorising the answer itself.
Approach MCQs conceptually, link physiology with clinical practice, and the guidelines will automatically make sense.Subscribe to Conceptual OBG for more insightful sessions to help you during your residency.
