Nutrition for the third trimester

During your final trimester of pregnancy, the baby’s organs increase in size and begin to function in preparation for working independently once the umbilical cord is cut. The most notable changes occur in the brain, where there is a very large increase in connections and activity, which prepares for behaviour such as breathing, movement and sensory awareness. Lungs and heart also prepare for taking the first breaths of air.

Keep up with the extra 300 calories that you added to your diet during the second trimester. You do not need any additional calories other than this to during the third trimester. Eating a variety of healthy foods will help to avoid nutrient deficiencies and support a healthy pregnancy and birth.

Key nutrients for the third trimester

Vitamin A

In your third trimester, you need more vitamin A to support your developing baby and increased blood volume.  Vitamin A contributes to the development of your baby’s eyes, immune system and skin cell production, and helps to develop the millions of tiny air sacs, called alveoli, in your baby’s lungs [1-2].

Beta-carotene vs Vitamin A 

Beta-carotene is a pigment found in orange and yellow coloured fruits and vegetables. It is converted in the body to the active form of vitamin A (retinol). Eating beta-carotene allows the body to regulate vitamin A status by only converting the amount that is needed [3].

Retinol is active form of vitamin A found in animal products.

Dietary sources of vitamin A

Beta-carotene: carrots, pumpkin, sweet potato, spinach, broccoli.

Retinol: Milk, eggs, organ meats, small whole fish (eg. sardines), liver oil.


Calcium helps your body regulate fluids, build your baby’s bones, and tooth buds, and support muscle, heart and nerve development. The daily requirement of calcium during pregnancy is around 1000 milligrams per day and 1300mg for women aged 18 years and younger [4].

Dietary sources of calcium:

Dairy, tofu, white beans, almonds, salmon, sesame seeds, cabbage


Magnesium is an essential mineral necessary for functions including transmission of nerve impulses and muscle contraction. During pregnancy, magnesium is required for healthy foetal development and supports sufficient blood flow to the brain [5]. Magnesium is also involved in building and developing bones, muscles, cells, and tissues.

Magnesium relaxes muscles and research suggests that getting adequate magnesium during pregnancy can help prevent the uterus from contracting prematurely causing preterm labour [6].

Dietary sources of magnesium:

Seeds, whole grains, green leafy vegetables, and legumes.

Omega 3 – DHA

DHA from omega-3 is important during pregnancy because it is a critical building block of the brain, retina, and nervous system. A baby’s brain development undergoes its most rapid and complex growth during the last trimester of pregnancy and the first two years after birth. DHA begins to accumulate in the brain at around 22 weeks’ gestation, increasing progressively until at least 2 years of age.  Healthy levels of DHA during pregnancy and after gestation significantly improve visual acuity and cognitive function in infants and toddlers [7].

Omega-3 intake also supports a healthy labour and delivery. Studies show that taking an omega-3 supplement during pregnancy can reduce the risk for pregnancy complications such as preeclampsia, preterm labour and low birth weight [8]. There is also an association between omega-3 intake and a reduced risk of post-natal depression [9].

Dietary sources of omega-3 – DHA

Tuna, salmon, herring, mackerel, sardine, marine algae (algal oil).

Remember that all nutrients are important and eating a balanced diet is the best way to support a healthy pregnancy.

For additional information, here is a list of important vitamins and minerals that play a role in the third trimester of pregnancy.

NutrientDietary sourcesFunction
Folic acid (Green leafy vegetables)Green leafy vegetablesPrevent preeclampsia, provide healthy birth weight, reduce risk of preterm delivery
Zinc (Seafood, lean meat)Seafood

Lean meat

Skin development, general cell development, differentiation and growth, immunity
Vitamin D (sunlight, eggs, fish)Sunlight exposure



Placental nourishment, gene transcription and regulation for important developmental stages
Iron (as per daily allowance, red meat, fish)Red meat



Haemoglobin production (oxygen transport) & neural development
B vitamins (Vegetables, lean red meat)Lean meat



General cell development. Important for red blood cell production (foetal circulation)
Iodine (Seafood, Seaweed, Vegetables, Iodized-salt)Seafood



Brain, neural development, general growth.
Omega-3 fatty acids (Seafood & fish)Seafood


Brain & neural development, general growth; general maternal health
Vitamin C (Citrus fruits)Citrus fruits

Tropical fruits

Cell and protein metabolism, increase iron absorption, antioxidant support, immunity
Vitamin E (Nuts and seeds)Nuts


Antioxidant support, cell growth and development
Magnesium (Vegetables, seeds, nuts, seafood, meat)Vegetables,

Nuts & seeds

Meat & seafood

Cell & muscle tissue development (skeletal development); maternal muscle and bone condition.
Calcium (Diary, milk, yogurt, cheese, vegetables)Dairy

Green vegetables

Sesame seeds

Skeletal formation, bone matrix growth and bone density, regulate circulatory system; regulates maternal muscle function and bone density.
Vitamin A/Beta-caroteneDairy




Sweet potato


Antioxidant protection, eye development, lung development, growth and development.
  1. Bastos Maia S, et al. Nutrients. 2019;11(3):681.
  2. Checkley W, et al. Engl J Med 2010 May 13; 362:1784.
  4. Pregnancy Nutrition :: American Pregnancy Association
  5. Belfort MA, et al. Engl J Med. 2003; 348(4):304-311.
  6. Okunade KS, et al. Adv Med. 2014;2014:704875.
  7. Carlson SE, Colombo J. Adv Pediatr. 2016;63(1):453-471.
  8. Middleton P, et al. Cochrane Database Syst Rev. 2018 Nov 15;11(11):CD003402.
  9. Markhus MW, et al. PLoS One. 2013;8(7):e67617.
Jenny Dang
Author: Jenny Dang

Hi there! I'm Jenny, a writer at Little Étoile with three years of experience in researching and crafting stories that make a difference. I'm on a mission to help moms and their little ones live healthier and happier lives through insightful and practical content. Let's make this journey of motherhood a delightful adventure together!