The study in brief
Some, but not all, previous research has suggested that being exposed to low levels of vitamin D in the womb may be associated with a higher risk of developing MS later in life. This study looked at if levels of vitamin D in the mother were related to the risk of their child developing MS later in life.
Since 1983 blood samples have been taken from pregnant women in Finland and stored in what is called the Finnish Maternity Cohort. This study involved 193 people with MS and 326 controls who were born after 1983. The researchers tested the blood samples from these participants’ mothers to measure the levels of vitamin D during pregnancy.
The study found that the children of mothers who had deficient levels of vitamin D early during their pregnancy were at increased risk of developing MS as an adult, when compared to those who had sufficient levels of vitamin D. However the study does have several limitations, which include not looking at other factors which may also the affect the risk of developing MS.
The study in detail
The cause of MS is not well understood, but it seems that genetic and environmental factors come together, to trigger MS in an individual. One of the environmental factors that has been studied is vitamin D, as many observations and studies have shown that low vitamin D could be a risk factor for developing MS.
Vitamin D is made in the skin when it is exposed to sunlight but it can also be consumed in the diet, by eating oily fish or foods that have had it added, such as breakfast cereals. Unborn babies receive vitamin D from their mothers.
Some, but not all, previous research has suggested that being exposed to low levels of vitamin D in the womb may be associated with a higher risk of developing MS later in life. This study looked at if levels of vitamin D in the mother were related to risk of their child developing MS later in life.
How this study was carried out
Since 1983 blood samples have been taken from pregnant women in Finland and stored in what is called the Finnish Maternity Cohort (FMC). The samples are taken at approximately 10 to 14 week’s into their pregnancies, and are used for routine tests and the extra sample is frozen for future research. The FMC now contains samples from almost all (approximately 98%) of the pregnancies that have occurred in Finland since 1983.
The researchers searched the Finnish hospital discharge registers to identify 193 people (163 were female) born between 1 January 1983 and 31 December 1991 (so aged between 18 and 27 at the time this study was conducted) that had been diagnosed with MS. They then identified the mothers and the pregnancy blood sample stored in the FMC.
These people with MS were matched to 326 controls for region of birth, date of sample collection, date of mother’s birth and date of child’s birth.
The researchers split vitamin D levels into three categories:
- Deficient - less and 12.02ng/mL
- Insufficient - between 12.02 and 20.03ng/mL
- Sufficient - greater than 20.03 ng/mL.
What was found
The study found that the children of mothers who had deficient levels of vitamin D early during their pregnancy were at increased risk of developing MS as an adult, when compared to those who had sufficient levels of vitamin D. However most of the mothers in the study had vitamin D levels below 20ng/mL, so most were deficient or at least had insufficient levels, only 10 mothers had levels over 30ng/mL.
Although MS is most commonly diagnosed between the ages of 20 and 40, the average age at MS diagnosis was 19.8 years old in the study participants, which reflects the fact that the study population only looked at people born after 1983.
What does it mean?
The study suggests that vitamin D deficiency may increase the risk of MS in the child, however the study does have several limitations. A mother’s vitamin D levels during pregnancy are not a direct measure of the vitamin D levels to which the developing baby is exposed to. Two previous studies also looking at the association between vitamin D levels in pregnancy or early life did not find an association with future MS risk in children. This includes a previous study covered in research update that measured vitamin D levels in new born babies, and also surveyed the participants as adults to look at other lifestyle and family aspects that may influence the risk of developing MS. As the current study only looked at vitamin D levels in the mother when the baby was still in the womb, it did not take into account other factors that are known to be risk factors for developing MS. Things such as genetics, smoking, being obese, having an Epstein-Barr virus infection or other lifestyle behaviours, which may have also had a role to play in whether they developed MS later in life.
The researchers conclude that while their study appears that low vitamin D levels in the mother may be related to the risk of developing MS in the child, it cannot tell us if increasing the mother’s vitamin D level would have an effect on this risk. Further studies would be needed to look at the relationship and these should involve more women with sufficient levels of vitamin D (over 20.03 ng/mL) as most women in this study had insufficient levels.
Munger KL, Åivo J, Hongell K, et al.
Vitamin D status during pregnancy and risk of multiple sclerosis in offspring of women in the Finnish Maternity Cohort.
JAMA Neurol. 2016 Mar 7. doi: 10.1001/jamaneurol.2015.4800. [Epub ahead of print]
More about vitamin D and MS
A lack of vitamin D may have a role in causing MS. It is known that multiple sclerosis is more common in countries further from the equator. As vitamin D is made in the skin, this has led to the hypothesis that low sunlight exposure and consequent low vitamin D production triggers the development of MS. Vitamin D may also play a role before birth as studies have shown more people with MS are born in May than in November. The mothers of these people would have been in the later stages of pregnancy during the darker months of the winter.
Vitamin D may also have a role in moderating relapses and disability in people who are already diagnosed with MS. There is some evidence that lower levels of vitamin D are associated with higher relapse rates and greater disability. Also, one study found that people with progressive forms of MS had lower levels than those with relapsing remitting MS.
Studies are underway to investigate both the role of vitamin D as a protective agent against the development of MS and as a treatment for people with the condition.
You can read more about vitamin D and MS in the A to Z of MS.
Vitamin D in pregnancy
The Department of Health currently recommends that all pregnant and breastfeeding women should take a daily supplement containing 10 micrograms (400 IU) of vitamin D to ensure that both them and their baby get enough vitamin D. Additionally it is recommended that all babies and young children aged six months to five years should also take a daily supplement, as vitamin D is needed for healthy teeth and bones and not enough vitamin D in children can lead to a condition called rickets.
You should talk with your MS nurse and midwife before taking supplements if you are trying for a baby or are pregnant to make sure you take the right combination and at an appropriate dose. As certain vitamins, especially vitamin A, can be dangerous to the unborn child as can high doses of the other vitamins.
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