Benefits of Combining Vitamin D and Fish Oil in Pregnancy and Beyond

By Vicki Zou, Medically reviewed by Dr. Patti Haebe, NMD | December 5, 2022

When it comes to pregnancy, you want the best for your baby! It’s common to wonder what supplements and vitamins should or should not be taken during pregnancy to ensure the best outcomes. So we’re breaking down the benefits of both Vitamin D and fish oil while trying to conceive or pregnant so you can make an educated decision on what vitamins and supplements should be part of your regimen with your obstetrician. 

Fish oil could benefit your pregnancy

Importance of Vitamin D in Pregnancy

Vitamin D is an incredibly important fat-soluble vitamin that helps the growth and maintenance of bones by helping the body absorb and retain calcium. 

The most common source of Vitamin D for most people is from the sun. That’s right, about 90% of Vitamin D comes from the sun, and around 10% comes from food we eat. Sunshine and animal sourced foods provide Vitamin D3, while plant sources and fortified foods, such as dairy products and cereals, contain added Vitamin D2. Vitamin D3 is more effective in raising overall Vitamin D levels than Vitamin D2 so get out there and grab some sunshine!

Source of Vitamin D

Vitamin D deficiency is common in pregnant women, around the world, 25% to 90% of pregnant women experience a deficiency of Vitamin D. In the U.S., 5% to 50% of pregnant women experience it. A deficiency of Vitamin D can lead to possible negative effects in both the mother and infant. For the mother, it can be associated with reduced fertility, hypertension in pregnancy, or an increase in blood glucose levels, which increases the risk of gestational diabetes mellitus — a condition in which a hormone made by the placenta prevents the body from using insulin effectively.” 

For the infant or child, Vitamin D deficiency in the mother during pregnancy is correlated to low birth weight, preterm birth, impaired respiratory health, or impaired language and motor development in young children. Because the fetus depends completely it’s mother for its Vitamin D levels, it is crucial for the mother to maintain sufficient Vitamin D levels throughout pregnancy. 

One easy way to avoid Vitamin D deficiency during pregnancy is to take prenatal supplements that include this essential nutrient. For the mother, Vitamin D supplementation during pregnancy is associated with increased calcium status — which helps support bone health in the mother and baby — and decreases the risk of hypertensive disorder. The ACOG recommends 1,000-2,000 IU of vitamin D daily during pregnancy.

Learn more supplement tips to get pregnant with a Premom app

For the infant, adequate Vitamin D levels are correlated with improved fetal growth and decreased risk of low birth weight or preterm birth. Taking Vitamin D supplements before pregnancy or during the early stages of pregnancy can help ensure that both you and your developing baby have sufficient levels of vitamin D. 

Importance of Fish Oil in Pregnancy

Fish oil is composed of two important omega-3 fatty acids called docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) and are used during the development of a fetus’s nervous system.

Consuming a sufficient amount of omega-3s, especially during pregnancy, has been found to be essential for both neurological and early visual development of the baby in addition to being an essential component in the production of breast milk.

Unfortunately, many people do not consume adequate levels of omega-3s in their diet and it is not well made by the body, therefore fish oil supplements help to ensure that mother’s and their babies receive the required amount of omega-3s. While pregnant it’s best to shoot for a minimum of 200 mg of DHA daily, however numerous studies support higher levels of DHA, such as 470mg, such as in Premom's Prenatal DHA  for optimal pregnancy outcomes.

Studies have shown that adding omega-3s to pregnant women’s diets “has a positive effect on visual and cognitive development of the baby” and can lower “the risk of allergies in infants.” DHA and EPA are also beneficial for mothers. Research has shown that higher consumption of these omega-3s can reduce the chances of a preterm birth and/or preeclampsia, may increase birth weight, and can lower the risk of depression during pregnancy. 

Vitamin D and Fish Oil,  Better Together

For maximum effectiveness, Vitamin D is a perfect companion to fish oil. Vitamin D is a fat-soluble vitamin, meaning it is absorbed along with fats in the diet and is stored in fatty tissue of the body and in the liver. Taking the two supplements in combination can promote better absorption.

Not a huge fan of supplementing? Feel free to take a ‘supplement holiday’ and instead opt for wild caught fish, 4 oz, 3 times a week and grab at least 20 minutes of full body sun exposure a day to obtain these nutrients naturally. Be sure to consult your doctor before stopping all supplements. 

The benefits of both Vitamin D and Omega-3 fish oil are numerous when it comes to pregnancy and lactation. Discuss with your doctor the importance of adequate Vitamin D and DHA during your pregnancy, and together develop a plan for the best regimen for your needs!


Learn more supplement tips to get pregnant with a Premom app



Harvard School of Public Health. (2022, January). Vitamin D.

Mulligan, M. L., Felton, S. K., Riek, A. E., & Bernal-Mizrachi, C. (2010). Implications of vitamin D deficiency in pregnancy and lactation. American journal of obstetrics and gynecology, 202(5), 429.e1–429.e4299. 

Johns Hopkins Medicine. (n.d.). Gestational Diabetes Mellitus (GDM).

Healthline. (2022, January 11). The Fat-Soluble Vitamins: A, D, E, and K. 

 American Pregnancy Association. (n.d.). Omega-3 Fish Oil and Pregnancy.


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