Vitamin D plays an important role in the development of your baby, as well as being vital for maintaining your bones, teeth and muscles. Despite this, around 1 in 5 people the UK are said to have low levels of the so-called ‘sunshine vitamin.’¹

As we’re spending more time in our homes, a daily dose of Vitamin D has never been more important to help you and your family stay well, and ensure the healthy development of your baby, pre and post-birth.

Vitamin D and bone development

If you don’t have enough Vitamin D in pregnancy or when breastfeeding, then it’s possible that your baby may not have enough calcium and phosphate in their system, which can lead to their bones and teeth being weak. In some instance, it’s possible for them to develop Rickets.²

Rickets is a condition that specifically affects bone development in children. It causes bone pain, poor growth and soft, weak bones that can lead to bone deformities. The adult form of Rickets is called Osteomalacia or soft bones.³

As well as potentially leading to bone development and strength issues, being low in Vitamin D during pregnancy may also mean there’s more chance of having a baby with a low birth weight.⁴

Sources of Vitamin D for pregnant women

Although it can be found in some foods, rich dietary sources of Vitamin D are rare. The foods with the highest levels of Vitamin D are herring, mackerel, sardines and eggs. It can also be found in fortified foods, such as breakfast cereals and soy milk products.⁵

You may be surprised to hear this, but even the healthiest of diets are unlikely to have enough Vitamin D⁶ in their systems because most of our Vitamin D comes from the sunshine.

However, in northern Europe, low Vitamin D levels are extremely common, especially in winter due to the lack of sunny days. There are also some groups of people who are at most risk of being low in Vitamin D. They are people:⁷

With darker, pigmented skin
Who are very overweight (with a BMI higher than 30)⁸
Who are over the age of 65

In the case of overweight and older people, they’re less likely to be out and about spending lots of time in the sun. Meanwhile, people who have naturally dark skin are at greater risk of being Vitamin D deficient because the pigment in their skin doesn’t absorb as much UV radiation.⁹

Why is Vitamin D so important when you’re pregnant?

You’ll know that calcium is important for the development of bones, muscles and teeth, and that calcium is especially important for pregnant women. However, if you don’t have enough Vitamin D, then your body can’t absorb calcium and phosphate properly.

In the second half of your pregnancy, Vitamin D is especially important, as this is when most of your baby’s bone growth occurs. A growing baby gets all of its Vitamin D from its mother’s stores, so pregnant women should be careful that they don’t have a lack of Vitamin D. The research on the role of Vitamin D in pregnancy has increased in recent years, as scientists have focused on the effects Vitamin D deficiency can have on babies.

The impact of Vitamin D on mums and babies

Lack of Vitamin D and birth weight

As we mentioned further up, lack of Vitamin D has been associated with lower birth weight in infants across several studies.¹⁰One Chinese study from 2017 found that maternal Vitamin D insufficiency is common during pregnancy and is associated with low birth weight and high risk of small gestational weight in infants.¹¹

Lack of Vitamin D and breathing/respiratory issues

Meanwhile, another study showed a marked reduction in the risk of infant wheeze from birth until the age of three when the mother has sufficient levels of Vitamin D.¹²

What’s more, separate trials have also found that children whose mothers took Vitamin D during pregnancy were less likely to become allergic to dust mites or other common air allergens and had a lower risk of asthma.¹³

Lack of Vitamin D and pre-term birth, diabetes and preeclampsia

Wider research has also linked a lack of Vitamin D during pregnancy with an increased risk of pre-term birth, gestational diabetes and preeclampsia (very high blood pressure during pregnancy) and bacterial vaginosis.¹⁴

Several clinical trials have found that supplemental Vitamin D lowers the risk of preeclampsia, especially when combined with supplemental calcium. One trial in particular found that for women who had preeclampsia in a prior pregnancy, high dose supplemental Vitamin D cut their risk of developing it again by half.¹⁵

Pregnant or planning on getting pregnant?

Don’t panic, because it’s unlikely that you have a true deficiency in Vitamin D. However, it’s likely your levels are low, mainly because rich dietary sources of Vitamin D are so scarce, and you may not necessarily be getting enough skin exposure every day to keep your Vitamin D levels topped up.

Ideally, you should aim to get between 10 and 30 minutes of midday sunlight several times a week. However, it’s important to note here that the amount of skin exposure will depend on how sensitive your skin is to sunlight.¹⁶And if you’re hoping to catch the sun’s rays by sitting in front of a window, it won’t have the same effect – skin that’s exposed to sunshine through windows does not produce Vitamin D.¹⁷

According to the official health guidelines from Public Health England people, including pregnant and breastfeeding women, should take 10mcg of Vitamin D supplements daily in the autumn and winter. And if you’re one of those people who are at risk of having low Vitamin D levels, you should ideally take supplements all-year round.¹⁸