Pregnancy & Children

UK health boards have long recommended that pregnant women take a small daily Vitamin D supplement of 400 IU (10 mcg) to prevent rickets. Although this recommended supplement might be enough to prevent rickets, it is generally not high enough to prevent other problems. At northern latitudes and in cooler climates, a 400 IU supplement simply isn’t sufficient to raise a pregnant woman’s blood level to even the lowest accepted threshold of 50 nmol/l, never-mind the 75 nmol/l minimum considered acceptable by

The Canadian Paediatric Society suggests that pregnant women, especially when living in northern areas like Scotland consider taking 2000 IU (50 mcg) daily. agree with this suggestion as we live at a similar latitude to Canada.

As well as Rickets, the modern viewpoint is that many diseases can be related to insufficient Vitamin D levels during pregnancy and children’s growth. These include autoimmune diseases such as multiple sclerosis, inflammatory bowel disease, diabetes mellitus, schizophrenia and autism. A large Danish study from 2021 showed that having higher vitamin D levels in early pregnancy and early childhood reduces risk of autism in the child. Pregnancy complications like gestational diabetes and pre-eclampsia might also be avoided with healthy Vitamin D supplies before and during pregnancy.

What About Safety?

A large American study from 2011 compared three groups of pregnant women, who were given either 400 IU (10 mcg) or 2000 IU (50 mcg) or 4000 IU (100 mcg) of Vitamin D. All doses were found to be safe.


Both women and men should make sure their Vitamin D stores are not low when trying to conceive. Sufficient Vitamin D in a man’s body helps to make healthy, well functioning sperm.

There is anecdotal evidence (from this author’s GP practice) that optimising the Vitamin D levels of both partners (getting them into the 100 – 150 nmol/l range), has been successful in helping to achieve pregnancy, where there was no other rectifiable cause. All things considered, there is certainly nothing to be lost by trying to optimise your Vitamin D levels.

Babies And Children

Babies need Vitamin D even if thought healthy, and especially when breast-fed. Most European countries, Canada and the US advise mothers to give their babies 400 IU (10 mcg) daily, starting at birth. This dosage is sufficient as a direct supplement to babies, but alternately if a breast feeding mother takes 6000 IU (150 mcg), then the baby won’t need an additional supplement.

In Summary

The level of Vitamin D in the body is one of many environmental factors which determines whether particular inherited genes become “live”. These include genes which predispose people to diseases like MS. We don’t yet know the exact age that genetic changes begin, so it is wise to ensure Vitamin D levels are good throughout a persons life, and certainly during pre-pregnancy, pregnancy, and from birth to adolescence.