What's the deal with taking vitamin D supplements during pregnancy?

The full breakdown of this important vitamin.
Written by
Ronelle Richards
Reviewed by
Last updated on
June 4, 2024
min read
Vitamin D During Pregnancy: Importance & Taking Supplements | Kin Fertility
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Pregnancy is an incredible nine months as you grow your baby. You've made lists, you've been on the Facebook pregnancy groups and you're trying to eat well and give your baby the best possible start.

Pregnant people are also highly susceptible to vitamin D deficiency, so it might make sense to start vitamin D supplementation.

When you have a blood test, your vitamin D levels are tested and for those with darker skin, a higher BMI, a lack of sunlight or lack of exposure to sunlight, there is a high chance you can be vitamin D deficient.

Some foods are fortified with vitamin D, like some plant-based milks or breakfast cereals, but this may not be enough to prevent a vitamin D deficiency. It's generally suggested pregnant people start vitamin D supplementation.

But what exactly is the deal with taking pregnancy supplements like vitamin D, especially for pregnant women?

Is it really that big a deal? Does your vitamin D status matter? Read on for the full breakdown.

What is vitamin D?

Vitamin D is a very important vitamin for all people, especially pregnant people. It helps your body absorb and retain calcium and phosphorus which are important for bone health.

High levels of vitamin D have also been associated with a reduced risk of cancer cell growth and inflammation. Further research into vitamin D has shown it could have an important role in balancing your immune system to give you a strong defence against viruses.

Vitamin D deficiency is very common amongst the general population especially in places with limited sun exposure or due to lifestyle choices like being indoors most of the time.

People with dark skin often have lower vitamin D levels due to the melanin in the skin reducing the production of vitamin D.

Why is vitamin D important for pregnancy?

A foetus is unable to produce vitamin D, which means it must be transferred from the mother via the placenta. From early pregnancy through to birth, vitamin D has a continued impact on your baby through breastfeeding. Put simply, vitamin D supplementation during pregnancy prevents vitamin D deficiency in your newborn.

Research has found a link between vitamin D deficiency in pregnancy and the musculoskeletal health of the children even as they enter adolescence and the bone health of your baby might be related to vitamin D supplementation during pregnancy.

Separate studies have found links between vitamin D deficiency in pregnant people and an increased risk of ADHD.

Conversely, higher levels of vitamin D during pregnancy (through vitamin D supplementation during pregnancy) have been shown to give children higher IQ scores.

What are the benefits of taking vitamin D supplements during pregnancy?

Low vitamin D levels can cause a higher risk of poor birth outcomes including preeclampsia and low birth weight. It can also impact the bone mass and bone growth of babies from the newborn stage through to the first year of their life.

Supplementation during pregnancy can help give your baby the best opportunity to absorb vitamin D and benefit from good bone mass, and skeletal health whilst reducing the relative risk of low birth weight.

Research from 2020 also showed a significant association between vitamin D deficiency and gestational diabetes. The level of vitamin D in pregnancy is strongly related to the outcome of gestational diabetes mellitus, which can endanger mother and baby and even result in neonatal deaths.

While research has found a link between vitamin D deficiency in early pregnancy and the development of gestational diabetes, this area does require more research.

But, it is safe to say that maternal vitamin D levels are incredibly important and can have positive benefits to the baby as well.

What are the benefits of taking vitamin D and calcium in pregnancy?

Calcium supplementation during pregnancy is known to have benefits for healthy bone growth and teeth. It complements vitamin D nicely and is often found together in a prenatal vitamin.

Taking calcium supplements during pregnancy elevates serum vitamin D and folic acid in pregnant women, which is critical in increasing the bone mass in infants.

Calcium supplementation during pregnancy is also strongly associated with a reduced risk of pregnancy-induced hypertension (high blood pressure).

How much vitamin D should you take in pregnancy?

There are a few factors to consider when it comes to how much vitamin D one person needs. In Australia, the current guidelines suggest pregnant people with vitamin D levels lower than 50 nmol/L should supplement.

While vitamin D is important in all stages of pregnancy, it's particularly crucial in the second and third trimester when your baby is growing strong bones.

Can you take too much vitamin D during pregnancy?

We know that low vitamin D levels can cause an increased risk of low birth weight compared to pregnant people with adequate maternal vitamin D levels, but what if you take too much?

If you exceed the recommended maximum daily limit of 4,000 IU/day of vitamin D during pregnancy, there is a higher risk of your baby developing hypercalcemia where there is too much calcium in the blood and a risk of weak bone mineral content.

Can you take a zinc supplement while pregnant?

Zinc deficiency can cause pregnancy complications like preterm birth, hypertension or even prolonged labour. It is also shown to possibly affect your infant's growth.

Zinc supplementation during pregnancy can help support your immune system and can counteract your risk of preterm birth.

What are the benefits of zinc during pregnancy?

Zinc is an essential mineral for your immune system, blood clotting function and wound healing. It also supports growth and development during pregnancy through antenatal care all the way through to our adolescence.

During pregnancy, it's important to get at least 10-11mg of zinc per day (Kin's Prenatal contains 14mg).

Is vitamin C important during pregnancy?

Like zinc, vitamin C plays an important role in keeping your immune system healthy. Vitamin C helps make collagen for you and your baby's skin and bones.

While vitamin C supplementation isn't required during pregnancy, it may help reduce the risk of pregnancy-related complications like pre-eclampsia and maternal anaemia.

The good news is that you can easily get adequate levels of vitamin C from foods like oranges, kiwi, lemon, capsicum, strawberries, tomatoes, broccoli, Brussels sprouts and cauliflower.

What is the best vitamin D supplement for pregnant women?

There are two types of vitamin D available for pregnant people. Maternal vitamin D deficiency is serious and should be tackled as early as possible. Don't leave it until your third trimester to address this issue as much of the research suggests that vitamin D supplementation is critical in early pregnancy.

Vitamin D can be split into D2 and D3. Much of the research to date has suggested that vitamin D3 has a greater impact on circulating vitamin D levels and is considered superior vitamin D supplementation compared to vitamin D2.

An additional study found vitamin D supplementation using D3 improved calcium levels more than vitamin D2.

If you have any concerns about your vitamin D levels during pregnancy, be sure to seek professional advice from your healthcare provider.

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