Diet in Pregnancy - Short Note

Energy Requirements

• Textbook of Family Medicine, 9e
• Biochemistry, 8th ed - Lippincott Illustrated Reviews

Recommended Weight Gain (Based on Pre-pregnancy BMI)

• Textbook of Family Medicine, 9e
• Guyton & Hall Textbook of Medical Physiology

Macronutrients

• Protein: Increased requirements for fetal tissue synthesis, especially in the third trimester.
• Fat: Adequate intake of omega-3 fatty acids (DHA) is recommended for fetal brain development.
• Carbohydrates: Balanced diet with whole grains and fiber is encouraged; processed, low-fiber foods should be limited.

Key Micronutrients

1. Iron

• Fetus requires ~375 mg of iron to form fetal blood.
• Mother requires an additional ~600 mg for her own expanded blood volume (plasma volume rises ~30% above normal).
• Normal maternal iron stores are only ~100 mg at the start of pregnancy (rarely >700 mg).
• Supplement: 30 mg/day elemental iron during the 2nd and 3rd trimester.
• Deficiency leads to hypochromic (iron deficiency) anemia in the mother.
• Guyton & Hall Medical Physiology

2. Folic Acid

• 400 mcg/day (periconception period through 1st trimester).
• Prevents neural tube defects (NTDs).
• Women at high risk (prior NTD pregnancy, epilepsy on anticonvulsants) receive 5 mg/day.
• Textbook of Family Medicine, 9e; Lippincott Biochemistry

3. Calcium & Phosphates

• Needed for fetal bone mineralization; stored by the mother in advance.
• Poorly absorbed without Vitamin D - hence both calcium and Vit D supplementation are important.
• RDA: 1000-1300 mg/day.
• Guyton & Hall Medical Physiology

4. Vitamin D

• Facilitates calcium absorption from the gut.
• Supplementation is typically recommended throughout pregnancy.
• Guyton & Hall Medical Physiology; Lippincott Biochemistry

5. Vitamin K

• Added near term so the newborn has adequate prothrombin levels.
• Prevents neonatal hemorrhagic disease of the newborn (especially intracranial hemorrhage during delivery).
• Guyton & Hall Medical Physiology

6. Iodine

• Required for fetal thyroid hormone synthesis and neurodevelopment.
• Deficiency can cause cretinism.
• Supplementation recommended throughout pregnancy.
• Lippincott Biochemistry

7. DHA (Docosahexaenoic Acid)

• Omega-3 fatty acid critical for fetal brain and retinal development.
• Found in oily fish; supplementation recommended especially if dietary intake is low.
• Lippincott Biochemistry

Fat-Soluble Vitamin Toxicity - Important Caution

• Vitamin A (retinol) excess is teratogenic - causes craniofacial defects, CNS malformations.
• RDA for Vitamin A in pregnancy is 2560 IU of retinol; many prenatal formulations provide beta-carotene (the non-toxic precursor) instead of preformed retinol to avoid teratogenicity.
• Creasy & Resnik's Maternal-Fetal Medicine; Textbook of Family Medicine, 9e

Foods to Avoid / Dietary Cautions

Practical Summary of Recommended Supplements

Note: In an adequately nourished woman with a singleton pregnancy, only iron and folic acid are universally recommended as individual supplements; a prenatal multivitamin covers other needs. However, because many women do not consume adequate vitamins and minerals from diet alone, broad supplementation is now standard practice.

• Textbook of Family Medicine, 9e

Key Exam Points (PG Short Note)

1. Extra caloric need = +300 kcal/day.
2. Iron need: fetus 375 mg + mother 600 mg; maternal stores are often insufficient - supplement 30 mg/day from 2nd trimester.
3. Folic acid: 400 mcg preconceptionally - prevents NTDs; start before conception.
4. Vitamin A excess is teratogenic - avoid high-dose retinol.
5. Vitamin K given near term to prevent neonatal hemorrhagic disease.
6. Vitamin D is needed for calcium absorption - always co-supplement.
7. Calcium and phosphate stores are built up by the mother early in pregnancy and released to the fetus in the 3rd trimester.
8. Maternal malnutrition is linked to childhood obesity and metabolic disease in offspring (Barker hypothesis / fetal programming).