Preventive strategies

Pre-conception Care - Building Blocks

• Folic Acid: Foundational for preventing Neural Tube Defects (NTDs).
  • Low-risk: 0.4 mg/day.
  • High-risk: 4 mg/day (history of NTD, on anti-epileptics like Valproate).
• Medical & Obstetric History: Screen for genetic conditions, chronic diseases (diabetes, hypertension, epilepsy), and prior pregnancy complications.
• Vaccinations: Ensure immunity against Rubella (MMR) and Varicella at least 1 month before conception.
• Teratogen Avoidance: Counsel on stopping alcohol, smoking, and non-prescribed drugs. Review and switch high-risk medications (e.g., ACE inhibitors, statins, warfarin).

⭐ Folic acid must be started at least 1 month before conception and continued through the first 12 weeks of gestation.

Nutritional Strategies - Fueling Futures

• Folic Acid (Vitamin B9): The cornerstone for preventing Neural Tube Defects (NTDs).
  • Standard Dose: 400 mcg/day for all women of childbearing age.
  • High-Risk (prior NTD): 4 mg/day.
  • Timing: Start ≥1 month before conception and continue through the first trimester.
• Iodine: Prevents congenital hypothyroidism and cretinism.
  • Primary strategy is universal salt iodization.
• Balanced Diet:
  • Ensures adequacy of iron, calcium, and other vital micronutrients.
  • ⚠️ Avoid excess Vitamin A (retinoids) due to teratogenic risk.

⭐ Periconceptional folic acid can reduce NTD risk by up to 70%. It is critical as the neural tube closes by day 28 post-conception, often before pregnancy is confirmed.

Teratogen Avoidance - Danger Zone

• Critical Period: Organogenesis (3-8 weeks post-conception) is the most vulnerable period. Before this, an "all-or-none" effect often applies.
• TORCH Infections:
  • 📌 Toxoplasmosis, Other (Syphilis, VZV), Rubella, Cytomegalovirus, Herpes.
  • Lead to deafness, cataracts, cardiac defects, microcephaly.
• Key Medications to Avoid:
  • ACE Inhibitors: Renal dysgenesis.
  • Valproate: Neural tube defects.
  • Thalidomide: Phocomelia (limb defects).
  • Isotretinoin: Craniofacial, cardiac, CNS defects.
• Other Exposures:
  • Alcohol: Fetal Alcohol Syndrome (smooth philtrum, thin upper lip).
  • Radiation: >5 rads exposure is teratogenic.

⭐ The embryonic period, from week 3 to week 8 post-conception, is the peak sensitivity window for teratogen-induced major congenital anomalies.

Prenatal Screening - Early Signals

• First Trimester (11-14 weeks)

  • Double Marker Test: Measures free β-hCG & PAPP-A.
  • Nuchal Translucency (NT) Scan: Measures fluid collection at fetal neck; value >3 mm is abnormal.

• Second Trimester (15-20 weeks)

  • Quadruple Test: Measures AFP, hCG, uE3, Inhibin A (📌 AHAI).
  • Targeted Imaging: Anomaly scan (TIFFA) at 18-20 weeks for structural defects.

⭐ The most common cause of elevated Maternal Serum AFP (MSAFP) is incorrect dating of the pregnancy.

High‑Yield Points - ⚡ Biggest Takeaways

• Periconceptional folic acid (400 mcg) is crucial for preventing Neural Tube Defects (NTDs); dose ↑ to 5 mg with a prior NTD history.
• Iodine supplementation in deficient areas prevents congenital hypothyroidism.
• Pre-pregnancy MMR vaccination is key to preventing Congenital Rubella Syndrome.
• Strict avoidance of teratogens like alcohol, valproate, and thalidomide is mandatory.
• Good maternal glycemic control reduces risks of VSD and caudal regression syndrome.
• Avoiding consanguineous marriages significantly lowers the risk of autosomal recessive disorders.