Lead

(Date of issue: December 2016. 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 Public Health England 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.

How might I be exposed to high levels of lead in pregnancy?

It is normal to be exposed to some lead as it occurs naturally in the soil, air, and water. However, exposure to high levels of lead may occur in certain situations, for example, during the removal of old lead-containing paint and through use of some ethnic medicines and cosmetics such as traditional kohl eyeliners. Old lead water pipes can result in higher levels of lead in drinking water. Women who work with wood preservatives, pesticides, dyes, varnishes, catalysts, waterproofing chemicals, or paint and pottery glazes may be at risk of being exposed to high levels of lead. High lead levels have also been observed in pregnant women who have eaten painted plaster due to cravings for non-food items.

Is it safe to be exposed to lead during pregnancy?

It is normal for some lead to be present in the body, and a lead measurement of less than 20 micrograms per litre of blood is considered acceptable in the UK. However, high levels of lead in the body are known to cause damage to the brain and nerves, and other health problems. During pregnancy lead crosses the placenta and can have a similar effect on the developing baby. Exposure to high levels of lead in pregnancy has also been linked in some studies to miscarriage, reduced growth of the baby in the womb, and premature labour. It is therefore recommended that pregnant women avoid exposure to high levels of lead, for instance by using protective equipment if stripping old paint, or at work if they are at risk of lead exposure. Pregnant women should also avoid the use of traditional medicines and cosmetics, especially where the ingredients are unknown and/or the products may be unregulated (such as those bought on the internet from an unknown source).

What if I have already been exposed to lead during pregnancy?

If you are pregnant and suspect you may have been exposed to high levels of lead you should speak to your doctor about this. They will most likely arrange for you to have blood tests to measure the levels of lead in your body. If these are found to be high, the likely source of lead needs to be identified so that further exposure can be prevented.

Are there any treatments for high lead levels?

Yes, women whose blood lead is above a certain level may be advised to take a type of medicine called a chelating agent to help remove the lead from the mother and thereby protect the baby. In the UK the chelating agents that are used are sodium calcium edetate or EDTA. Although there is not much information on use of either of these medicines in pregnancy they do not appear to be harmful to a baby in the womb and high lead levels are likely to be much riskier to a baby in the womb than any possible risk posed by these medicines. Your doctor will be able to advise you on what is best for you and your baby.

Can exposure to high levels of lead during pregnancy cause 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 exposure to chemicals, medicines, and other substances could potentially cause birth defects.

Studies of over 7,000 women with suspected or confirmed exposure to high levels of lead in pregnancy show that they are no more likely to have a baby with a major birth defect than women thought not to be exposed to high levels of lead. However, one study has found a possible link between exposure to high levels of lead in early pregnancy and neural tube defects (such as spina bifida), and another study to heart defects in the baby. Because no study is perfect, information on many more pregnant women exposed to high levels of lead needs to be collected to further assess these findings.

Can exposure to high levels of lead in pregnancy cause miscarriage?

A single modern study has found that increased blood lead levels in pregnancy may be linked to miscarriage. Older studies also reported similar findings, but because of how these studies were designed it is possible that the results are not reliable. Further studies are therefore required before we can say for sure whether exposure to high levels of lead in pregnancy increases the likelihood of miscarriage. 

Can exposure to high levels of lead cause stillbirth?

No studies have investigated the likelihood of stillbirth following exposure to high levels of lead in pregnancy.

Can exposure to high levels of lead cause low birth weight in the baby?

Seven studies have all provided evidence of a link between exposure to high levels of lead in pregnancy and reduced growth of the baby in the womb. The two studies that specifically investigated the occurrence of low birth weight in the baby (<2,500g), or the baby being smaller than expected for the stage of pregnancy, both showed a link with exposure to high levels of lead in pregnancy.

Can exposure to high levels of lead cause premature delivery (<37 weeks)?

Six out of the seven studies that investigated this concluded that high lead levels in pregnancy may increase the chance of the baby being born prematurely. Some of these studies also showed that, in general, the higher the mother’s lead level the earlier the baby was likely to be born.

Can exposure to high levels of lead cause learning or behavioural problems in the child?

A baby’s brain continues to develop right up until the end of pregnancy. It is therefore possible that exposure to certain substances at any stage of pregnancy could have a lasting effect on a child’s learning or behaviour.

High levels of lead can damage a child’s or adult’s brain and nerves. Unsurprisingly therefore, a number of studies have shown that exposure in the womb to high levels of lead can affect a child’s intelligence and may be linked to learning problems.

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.

If blood tests have shown that you have high levels of lead during pregnancy you may be offered additional monitoring to check that your baby is growing and developing as expected. You will probably also receive further blood tests to recheck your lead levels for the rest of your pregnancy.

Are there any risks to my baby if the father has been exposed to high levels of lead?

A single study has shown that miscarriage or reduced growth of the baby in the womb may be more likely in pregnancies where the father had high blood lead levels around the time of conception. More research is required to confirm this finding.

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 health care provider. They can access more detailed medical and scientific information from www.uktis.org.

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.

   

www.medicinesinpregnancy.org

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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