Third trimester nutrition for growth and comfort

The Third Trimester: When Fetal Growth Is Most Intensive

The third trimester (weeks 27–40) is the most nutritionally demanding phase of pregnancy. The fetus more than doubles in weight between 28 and 40 weeks. Brain development — particularly DHA accumulation in the cerebral cortex — is most intense from 32 weeks through the first year of life. Iron stores are transferred to the fetus almost entirely in the last trimester. Total additional calories needed are approximately 400–450 kcal above pre-pregnancy maintenance.

DHA: The Brain-Building Fatty Acid

DHA constitutes approximately 25–30 percent of the brain’s structural fat. The fetal brain accumulates DHA most rapidly from 28 weeks onward, drawing from maternal stores and diet. Maternal DHA supplementation during the third trimester is associated with improved infant visual acuity and cognitive function in multiple randomised trials. Target: 200–300 mg of DHA daily, from low-mercury fatty fish eaten 2–3 times weekly, or from algae-derived DHA supplements for those avoiding fish.

Managing Heartburn Without Compromising Nutrition

Gastroesophageal reflux affects up to 80 percent of women in the third trimester. Helpful strategies: eat smaller meals every 2–3 hours; avoid eating 2–3 hours before lying down; sleep with the head elevated 15–20 cm; limit triggering foods (fatty foods, chocolate, citrus, tomato, spicy, mint, coffee). Safe medications: antacids (calcium carbonate-based), alginates, and H2 blockers are generally considered safe in pregnancy — confirm with your provider for correct timing and dose.

Third Trimester Weight Gain: Context

Recommended total pregnancy weight gain depends on pre-pregnancy BMI. Much of third trimester weight gain reflects expanded blood volume, amniotic fluid, placenta, fetal growth, and fluid retention — not primarily fat accumulation. If weight gain seems high, focus on food quality (reducing ultra-processed, high-sodium foods) rather than restriction. Inadequate nutrition in the final trimester impairs fetal brain development, bone mineralisation, and iron accumulation — restriction is not a safe strategy at this stage.

Key Takeaways

This article on Third trimester nutrition for growth and comfort is designed to give you clear, evidence-informed steps to discuss with your care team. Every fertility journey, pregnancy, and IVF cycle is unique — use this as a starting framework and build your individual plan with your doctor, midwife, or registered dietitian. For safety-critical decisions, current evidence and your clinical team always take precedence over general guidance.

Visual Guide

Keep this one practical: use the first image to understand the context, then apply one actionable step today before moving to the next section.