(Date of issue: March 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.
What is it?
Labetalol is a medicine that is prescribed to treat high blood pressure. Labetalol belongs to a family of medicines called beta-blockers. The National Institute for Health and Care Excellence (NICE) is a government body in the UK that produces guidelines for doctors. NICE recommends that women who have high blood pressure that started during pregnancy (sometimes called gestational hypertension or pregnancy-induced hypertension) are treated with labetalol wherever possible. Additionally, some women who were being treated for high blood pressure before pregnancy might be switched during pregnancy from their previous medicine to labetalol.
Is it safe to take labetalol in pregnancy?
There is no yes or no answer to this question. When deciding whether to use labetalol during pregnancy it is important to weigh up how necessary labetalol is to your health against any possible risks to you or your baby, some of which might depend on how many weeks pregnant you are.
It is important to appropriately treat high blood pressure in pregnancy. Studies have shown that poorly controlled high blood pressure in pregnancy is linked to an increased risk of certain birth defects, stillbirth, the baby growing more slowly than normal in the womb, and premature birth. For some women with high blood pressure, treatment with labetalol in pregnancy might be considered to be the best option. Your doctor is the best person to help you decide what is right for you and your baby.
What if I have already taken labetalol during pregnancy?
If you have taken any medicines it is always a good idea to let your doctor know that you are pregnant so that you can decide together whether you still need the medicines that you are on and, if so, to make sure that you are taking the lowest dose that works.
Can taking labetalol 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.
Single studies have investigated whether use of labetalol in early pregnancy increases the occurrence of heart defects or hypospadias (where the opening of the penis is on the underside rather than at the tip) in the baby. At present, the evidence does not suggest a link between labetalol use in pregnancy and these defects. Hypospadias and heart defects have, however, been found to be more common in women with untreated high blood pressure. Further large studies are required before we can say whether use of labetalol in early pregnancy might increase the risk of hypospadias, heart defects, and other birth defects in the baby.
Can taking labetalol in pregnancy cause miscarriage
No studies have assessed miscarriage rates in women taking labetalol. Scientific research into this subject is therefore required.
Can taking labetalol in pregnancy cause stillbirth?
Poorly controlled high blood pressure in pregnancy is known to increase the risk of stillbirth. This needs to be considered when assessing whether medicines that are used to treat high blood pressure in pregnancy might also increase the risk of stillbirth.
A single large study showed that women taking labetalol in pregnancy were more likely to experience a stillbirth compared to women in the general population. However, because this study did not take into account the effect of their high blood pressure on the risk of stillbirth, it is not possible to say whether taking labetalol altered the risk.
Two smaller studies that did take into account the effects of high blood pressure on risk of stillbirth showed that women taking labetalol in pregnancy were at no greater risk of stillbirth than women taking other medicines for high blood pressure. Further large-scale studies like these are required before we can say whether taking labetalol in pregnancy affects a woman’s risk of stillbirth.
Can taking labetalol in pregnancy cause preterm birth (before 37 weeks)?
Women with poorly controlled high blood pressure in pregnancy are more likely to give birth early (preterm). Early delivery of the baby is sometimes medically induced because of the severity of the mother’s high blood pressure, or due to concerns about the baby’s health in the womb. Studies do not always provide information on whether early delivery was spontaneous or induced. It is therefore not always possible to work out whether medicines that are used to treat high blood pressure in pregnancy increase the risk of spontaneous preterm birth.
Eleven studies of preterm birth rates in a total of over 1,000 pregnant women taking labetalol have been carried out. All of these studies used methods that accounted for the underlying effects of high blood pressure in the mother. Ten of the eleven studies found that taking labetalol in pregnancy does not further increase the risk of preterm birth. Although this is reassuring, the study that did show an increased risk was one of the largest carried out so far, which means that it may have provided more reliable results than some smaller studies. More large studies are therefore required before we can confirm that use of labetalol.in pregnancy does not increase the risk of preterm birth.
Can taking labetalol in pregnancy cause my baby to be small at birth (low birth weight)?
Poorly controlled high blood pressure in pregnancy is known to increase the risk of low birth weight in the baby. It is therefore complicated to work out whether medicines that are used to treat high blood pressure in pregnancy themselves increase the risk of low birth weight.
Eleven studies of low birth weight rates in the babies of over 1,300 pregnant women taking labetalol have been carried out. All of these used methods that accounted for the underlying effects of high blood pressure in the mother. Eight of the eleven studies found no evidence that taking labetalol in pregnancy further increases the risk of low birth weight in the baby, or the baby being smaller than expected for the stage of pregnancy. Although this is reassuring, one of the studies that did show an increased risk was one of the largest carried out so far, which means that it may have provided more reliable results than some smaller studies. More large studies are therefore required before we can confirm that use of labetalol.in pregnancy does not increase the risk of low birth weight in the baby.
Can taking labetalol in pregnancy cause other health problems in the baby/child?
Complications after birth
Side effects of beta-blockers include low heart rate, low blood sugar, and low blood pressure. Babies of women who are treated with beta-blockers around the time of delivery might therefore experience these effects for a few hours or days after birth. Some studies found that these effects are more likely in newborn babies exposed to labetalol in the womb than in babies not exposed to labetalol. However, other large studies suggest that exposure to labetalol in the womb does not increase the likelihood of problems in the baby after birth. The chance of the baby having problems after birth is therefore uncertain. If you have taken labetalol in the weeks before delivery, your doctor or midwife might arrange for your baby to be born at a unit that can monitor and treat your baby if necessary.
Learning and behavioural problems in the child
A baby’s brain continues to develop right up until the end of pregnancy. It is therefore possible that taking certain medicines at any stage of pregnancy could have a lasting effect on a child’s learning or behaviour.
A single small study showed that children exposed to labetalol in the womb were more likely to be diagnosed with attention deficit hyperactivity disorder (ADHD) compared to children whose mothers had high blood pressure in pregnancy that was not treated with medicines. However, labetalol-exposed children were no more likely to be diagnosed with ADHD than children exposed in the womb to a different high blood pressure medicine. This result needs to be confirmed in much larger studies, but suggests that any effect is not specific to labetalol. Two further small studies provided no evidence that children exposed to labetalol in the womb are at increased risk of other learning and developmental problems.
Many more children exposed to labetalol in the womb need to be studied before we can say whether it has any effects on learning and behaviour.
Will I or my baby need extra monitoring during pregnancy or after delivery?
Most women will be offered a scan at around 20 weeks of pregnancy to look for birth defects as part of their routine antenatal care. Using labetalol in pregnancy is not expected to cause problems that would require extra monitoring of your baby during pregnancy. However, women with high blood pressure are likely to be offered specialist care in addition to their normal midwife appointments during pregnancy, and to be more closely monitored to ensure that their blood pressure is in the correct range, and their baby is growing and developing as expected.
Women with high blood pressure in pregnancy are also advised to monitor themselves for symptoms of a severe form of high blood pressure called pre-eclampsia. If you are experiencing symptoms of pre-eclampsia you should seek urgent medical help. Symptoms of pre-eclampsia include:
• Severe headaches that often do not get better after using pain relief
• Visual problems, such as blurred vision, flashing lights, double vision, or floating spots
• Pain under the ribs, especially on the right-hand side
• Being sick
• Feeling breathless
• Sudden swelling of the face, hands, or feet
Babies born to women who used labetalol in late pregnancy might be closely monitored after birth to ensure that they are not experiencing adverse effects of beta-blocker exposure, such as low heart rate, low blood sugar, and low blood pressure. Babies experiencing these effects might require treatment and support for a few hours or days after delivery.
Are there any risks to my baby if the father has taken labetalol?
No studies have specifically investigated whether labetalol taken by the father can harm the baby through effects on the sperm, however most experts agree that this is very unlikely. More research on the effects of medicine use in men around the time of conception is needed.
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.
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.