Use of vitamin D supplements

(Date: February 2019. Version: 2)

This factsheet has been written for members of the public by the UK Teratology Information Service (UKTIS). UKTIS is a not-for-profit organisation funded by the UK Health Security Agency (UKHSA) on behalf of UK Health Departments. UKTIS has been providing scientific information to health care providers since 1983 on the effects that medicines, recreational drugs and chemicals may have on the developing baby during pregnancy.

What is it?

Vitamin D occurs in oily fish, cod liver oil, red meat, liver, egg yolks, and is added to foods such as margarine and breakfast cereal. Vitamin D is naturally produced in the body from sunlight on the skin. It is also present in some vitamin supplements. Vitamin D is needed for the body to absorb calcium and deficiency can lead to weak and soft bones (rickets).

Is it safe to take vitamin D in pregnancy?

In the UK it is recommended that pregnant women take a daily supplement containing 10 micrograms of vitamin D.

UK guidelines also suggest that pregnant women with a diagnosed vitamin D deficiency can be treated with high dose vitamin D under supervision by a doctor.

What if I have already taken vitamin D during pregnancy?

Vitamin D supplements (10 micrograms per day) are recommended in pregnancy. If you have taken higher dose vitamin D in pregnancy without medical supervision you should discuss this with your doctor or midwife. Additionally, if you are pregnant and have taken any medicines it is always a good idea to let your doctor know in case an adjustment of dose is required and/or you need any additional monitoring or treatment.

This leaflet summarises the scientific studies relating to the effects of vitamin D on a baby in the womb.

Can taking vitamin D in pregnancy cause my baby to be born with birth defects?

A baby’s body and most internal organs are formed during the first 12 weeks of pregnancy. It is mainly during this time that some medicines are known to cause birth defects.

There is no evidence that vitamin D supplements in early pregnancy are linked to birth defects in the baby. Small numbers of mothers receiving higher dose vitamin D have also not shown that this causes birth defects in the baby.

Can taking vitamin D in pregnancy cause miscarriage?

No studies have investigated the chance of miscarriage in women taking vitamin D in pregnancy.

Can taking vitamin D in pregnancy cause stillbirth?

A study of 540 pregnant women taking vitamin D supplements in pregnancy found that they did not have a higher chance of stillbirth compared to women not taking a vitamin D supplement.

Can taking vitamin D in pregnancy cause preterm birth or my baby to be small at birth (low birth weight)?

Studies of pregnant women taking vitamin D supplements in pregnancy found that they did not have a higher chance of preterm birth or of the baby having a low birth weight compared to women not taking a vitamin D supplement. However, one large study found that pregnant women taking supplements containing both vitamin D and calcium were slightly more likely to have a preterm delivery. It is unclear whether this might be because women taking calcium supplements in pregnancy may be doing so because of underlying health issues, which might themselves increase the chance of preterm birth. Further research is therefore required.

Can taking vitamin D in pregnancy cause learning or behavioural problems in the child?

No studies have investigated learning and development in children whose mothers took vitamin D supplements during pregnancy.

Will my baby need extra monitoring during pregnancy?

As part of their routine antenatal care most women will be offered a scan at around 20 weeks of pregnancy to look for birth defects and to check the baby’s growth.

Taking vitamin D in pregnancy is not expected to cause any problems that would require extra monitoring.

Are there any risks to my baby if the father has taken vitamin D?

We would not expect any increased risk to your baby if the father took vitamin D before or around the time you became pregnant.

Who can I talk to if I have questions?

If you have any questions regarding the information in this leaflet please discuss them with your healthcare provider. They can access more detailed medical and scientific information from

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General information 

Up to 1 out of every 5 pregnancies ends in a miscarriage, and 1 in 40 babies are born with a birth defect. These are referred to as the background population risks.  They describe the chance of these events happening for any pregnancy before taking factors such as the mother’s health during pregnancy, her lifestyle, medicines she takes and the genetic make up of her and the baby’s father into account.

Medicines use in pregnancy

Most medicines used by the mother will cross the placenta and reach the baby. Sometimes this may have beneficial effects for the baby.  There are, however, some medicines that can harm a baby’s normal development.  How a medicine affects a baby may depend on the stage of pregnancy when the medicine is taken. If you are on regular medication you should discuss these effects with your doctor/health care team before becoming pregnant.

If a new medicine is suggested for you during pregnancy, please ensure the doctor or health care professional treating you is aware of your pregnancy.

When deciding whether or not to use a medicine in pregnancy you need to weigh up how the medicine might improve your and/or your unborn baby’s health against any possible problems that the drug may cause. Our bumps leaflets are written to provide you with a summary of what is known about use of a specific medicine in pregnancy so that you can decide together with your health care provider what is best for you and your baby.   

Every pregnancy is unique. The decision to start, stop, continue or change a prescribed medicine before or during pregnancy should be made in consultation with your health care provider. It is very helpful if you can record all your medication taken in pregnancy in your hand held maternity records.

Disclaimer: This information is not intended to replace the individual care and advice of your health care provider. New information is continually becoming available. Whilst every effort will be made to ensure that this information is accurate and up to date at the time of publication, we cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes following decisions made on the basis of this information. We strongly advise that printouts should NOT be kept for any length of time, or for “future reference” as they can rapidly become out of date.

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