The third trimester, beginning around week 28 of pregnancy, is the final and most intensive phase of fetal development. This period features the most rapid growth in fetal weight and organ maturation, particularly the brain and lungs. Consequently, nutritional demands shift significantly compared to earlier months of gestation. Adequate caloric intake is necessary to support the mother’s changing physiology and the accelerated development of the fetus.
Recommended Daily Caloric Increase
For women who began pregnancy at a healthy weight, the recommended daily energy intake involves adding approximately 450 to 500 extra calories per day to pre-pregnancy needs. This targeted increase supports the final stages of fetal growth and the overall maternal metabolic increase, unlike the first trimester where no additional calories are typically required.
This additional energy supports substantial physiological changes. The fetus gains a significant portion of its birth weight during these final weeks, requiring a reliable supply of energy and building blocks. The mother’s body also develops increased blood volume, a larger uterus, and a heavier placenta, contributing to an elevated resting metabolic rate.
The extra calories also contribute to building maternal energy stores, preparing the body for labor and the energy demands of postpartum recovery and lactation. While this approximate number provides a clear guideline, the focus should be on nutrient-dense food sources rather than solely on the total number of calories consumed.
Prioritizing Key Nutrients
While total caloric intake is important, the source of those calories matters more to support the specialized growth of the third trimester. Specific nutrients must be prioritized to assist in the rapid development of the fetal brain, skeleton, and circulatory system. These building blocks are often required in increased amounts beyond a standard prenatal vitamin.
Iron is crucial because the mother’s blood volume expands up to 50%, and the fetus accumulates iron stores for its first six months of life. Sufficient iron intake helps prevent maternal anemia and ensures proper oxygen delivery to the baby. Sources include lean red meat, fortified cereals, and legumes. Consuming iron alongside vitamin C can enhance absorption.
Protein requirements increase substantially to support the synthesis of new fetal tissue and maternal growth. Experts recommend aiming for 70 to 100 grams of protein daily, found in poultry, fish, eggs, and dairy products. The rapid calcification of the baby’s bones necessitates increased calcium intake, sourced from dairy, fortified plant-based milk, and dark leafy greens.
Vitamin D works in tandem with calcium, helping the body absorb the mineral needed for skeletal development. Docosahexaenoic Acid (DHA), an omega-3 fatty acid, is crucial for the optimal development of the fetal brain and retina, which rapidly accumulates these fats. Fatty fish like salmon, or DHA supplements, help meet the recommended daily intake of 200 to 300 milligrams.
Personalizing Calorie Intake
The general caloric recommendation is a starting point, but individual needs require adjustment based on several maternal factors. The number of fetuses is a significant variable; a twin pregnancy necessitates a much higher caloric intake. Women expecting multiples may need a daily increase closer to 600 or more calories beyond pre-pregnancy needs to support the growth of two placentas and two babies.
Pre-pregnancy Body Mass Index (BMI) plays a substantial role in determining caloric guidance. Women who were underweight may require a higher daily caloric increase than the standard recommendation. Conversely, women categorized as overweight or obese may need a smaller caloric increase, around 350 extra calories per day, focusing on gaining weight more gradually within established guidelines.
A woman’s activity level throughout the third trimester is another factor modifying energy requirements. An individual who maintains a high level of physical activity or an active job will have a higher total energy expenditure than someone who is largely sedentary. Because these adjustments are complex and tied to health history, consulting a healthcare provider or a registered dietitian is the most effective way to establish a personalized caloric plan.