Deficiencies Common in Third Trimester

The third trimester, from week 27 until delivery, is a period of intense fetal growth and preparation for birth. The baby gains most of its weight during these final weeks, with fat stores, brain tissue, and lung maturity all developing rapidly. The mother's body is also preparing for labor, delivery, and breastfeeding, all of which place significant demands on nutrient reserves.

During this trimester, the baby is actively building iron stores that will sustain it through the first four to six months of life after birth. This means that maternal iron demand peaks during the third trimester. Similarly, calcium transfer to the baby's skeleton intensifies, and DHA accumulation in the baby's brain reaches its highest rate. Nutritional deficiencies that were borderline in earlier trimesters can become clinically significant during this critical final stage.

Iron deficiency reaches its peak prevalence in the third trimester because of the cumulative effect of months of increased demand. Even women who have been taking iron supplements throughout pregnancy may find that their hemoglobin levels dip during this period if their starting stores were low or if absorption has been suboptimal. Third-trimester anemia is a serious concern because it increases the risk of postpartum hemorrhage, the need for blood transfusion during delivery, and maternal fatigue during the early postpartum period.

For the baby, third-trimester iron stores are critical. Babies born to iron-deficient mothers may have lower iron reserves at birth, putting them at risk for iron-deficiency anemia in infancy, which can affect cognitive and motor development. Ensuring adequate iron status in the final weeks of pregnancy is therefore important for the baby's health beyond birth. Your doctor may recheck your hemoglobin around 32 to 36 weeks and adjust supplementation accordingly.

Calcium transfer to the baby peaks during the third trimester, with approximately 200 to 300 mg of calcium being deposited into the baby's skeleton daily. This dramatic demand can significantly deplete the mother's calcium levels if dietary intake and supplementation are not sufficient. Symptoms may include worsening leg cramps, especially at night, back pain, and in severe cases, loosening of teeth due to calcium withdrawal from the jawbone.

Vitamin D deficiency in the third trimester can impair both calcium absorption and immune function at a time when the mother needs to be as healthy as possible for delivery. Some research has linked low maternal vitamin D levels in late pregnancy with a higher risk of preterm delivery and low birth weight. Ensuring adequate vitamin D through supplementation and safe sun exposure remains important right through the final weeks of pregnancy.

The baby's brain undergoes its most rapid period of growth during the third trimester, with DHA (docosahexaenoic acid), an omega-3 fatty acid, being a critical building block of brain and retinal tissue. The baby's brain triples in weight during the last trimester, and DHA makes up a substantial portion of the brain's structural fat. Insufficient maternal DHA intake during this period may compromise optimal brain and visual development.

Many Indian diets are low in DHA, particularly vegetarian diets. While plant sources like flaxseeds and walnuts provide the precursor omega-3 (ALA), the conversion rate to DHA in the body is very low, typically less than 5 percent. Women in Visakhapatnam who eat fish regularly have an advantage, as fatty fish such as sardines and mackerel are excellent DHA sources. For those who do not eat fish, an algae-based DHA supplement is recommended during the third trimester.

Vitamin K needs increase in the final weeks of pregnancy as the body prepares for the bleeding associated with delivery. Ensuring adequate vitamin K intake through green leafy vegetables supports the mother's clotting function and reduces the risk of excessive bleeding during and after delivery.

Protein needs also peak during the third trimester to support the baby's rapid weight gain and the mother's preparation for lactation. Many pregnant women in India do not consume enough protein, particularly vegetarian women. Aim for at least 75 to 80 grams of protein daily from sources like dal, paneer, eggs, nuts, and soy products. Magnesium and zinc continue to be important for preventing cramps, supporting immune function, and preparing the body for labor.

Third-trimester antenatal visits become more frequent, typically every two weeks from week 28 to 36 and then weekly until delivery. These visits are crucial for monitoring your nutritional status, assessing the baby's growth through ultrasound measurements, and making any final adjustments to your supplementation plan. Report any new or worsening symptoms such as severe fatigue, swelling, headaches, or reduced fetal movement to your doctor immediately.

If you are planning to breastfeed, discuss your postnatal nutritional needs during your third-trimester visits so that you can begin preparing. Many of the same nutrients that are important in late pregnancy, including iron, calcium, vitamin D, and DHA, remain essential during breastfeeding. Your prenatal care team at Heamac Healthcare in Visakhapatnam can help you transition smoothly from pregnancy nutrition to postnatal nutrition, ensuring that both you and your baby are well-supported during this important time.