Chapter 4: Nutrition During Pregnancy

The maternal body undergoes substantial adaptations, including expansion of blood plasma volume by nearly fifty percent to facilitate nutrient and oxygen delivery to the developing fetus, alongside metabolic shifts that prioritize glucose availability for fetal consumption. The placenta serves as a selective barrier between maternal and fetal circulations, though its filtering capacity is incomplete and allows certain substances to cross. Fetal development proceeds through critical windows of rapid cell division, known as hyperplasia, during which nutritional insufficiencies can trigger developmental programming—permanent changes in fetal physiology and gene expression—that may predispose offspring to chronic metabolic and cardiovascular diseases in adulthood. Appropriate maternal weight gain is individualized according to prepregnancy body mass index, with recommendations varying based on starting weight categories. Folic acid supplementation before conception and during early pregnancy is emphasized as essential for preventing neural tube defects in the developing nervous system. Long-chain polyunsaturated fatty acids, particularly docosahexaenoic acid and eicosapentaenoic acid, are critical for fetal brain and eye development. The chapter challenges common assumptions about sodium restriction during pregnancy, noting that routine limitation is unnecessary absent specific medical conditions. Iron supplementation is discussed with attention to appropriate dosing, as excessive supplementation can impair mineral absorption and create adverse effects. Food safety receives significant attention, with emphasis on avoiding pathogens such as Listeria monocytogenes and Toxoplasma gondii that pose particular risks to fetal development. Finally, the chapter addresses prenatal nutrition assessment methods, including interpretation of biomarker concentrations that naturally shift during gestation and evaluation of dietary patterns according to established food group recommendations.