WILL - When to Induce Labour to Limit risk from high blood pressure in pregnancy

 

The WILL trial aims to find out if it is safer for women who have high blood pressure during pregnancy to have their babies delivered slightly early, or to let the pregnancy carry on as usual.

 

High blood pressure during pregnancy can lead to complications for women and babies. Currently, most pregnant women with high blood pressure at 40 weeks are offered an induction (artificially starting labour using hormones) or Caesarean section to reduce the risks of continuing with the pregnancy. It is possible that delivering the baby before 40 weeks could reduce the chance of health problems and stillbirth. But it is also possible that an early delivery could increase the chance of complications for the baby.

This trial is testing whether planned delivery at 38 weeks is better overall than monitoring the woman and unborn baby until at least 40 weeks. The research team are also interested in finding out if there is any link between the two different times of delivery and the baby’s health and their wellbeing in later life, such as how well they perform at school.

During the trial women will be randomly put into two different groups: one for planned delivery of the baby at 38 weeks gestation, the other for monitoring the pregnancy until 40 weeks. This ensures that a fair comparison of the two groups can be made. The research team will analyse any differences between the number of health problems or stillbirths in each group to see whether planned delivery at 38 weeks does reduce these risks or not.

Sands has supported the research team in the design of this study and was closely involved in highlighting the importance of finding a balance between minimising risks of health problems from delivering a baby early and reducing the risk of stillbirth from continuing pregnancy. Along with Action on Pre-Eclampsia (APEC), Sands has helped to set up a Parent Advisory Group so that parents can help to support the research team throughout the project.

More Information

Why do we need this research?

Each pregnancy will have different factors that determine the chances of complications; high blood pressure during pregnancy is more common in older or obese women. Compared to women who have normal blood pressure during pregnancy, women who develop high blood pressure are more likely to suffer from serious health problems themselves, or to have a stillbirth.

There is little information to guide doctors and women with high blood pressure when they make decisions about timing of delivery. Currently, most pregnant women with high blood pressure at 40 weeks gestation are offered induction of labour or Caesarean section to minimise the risks of continuing with the pregnancy. This trial is testing whether planned delivery at 38 weeks is better overall than monitoring the woman and unborn baby until at least 40 weeks. Previous research looking at North American data suggested that starting labour at 38 weeks gave the best trade-off between minimising the risk of stillbirth and the risk of health problems for the baby from being delivered early. However, this research did not specifically investigate pregnant women with high blood pressure, for whom the risks are greater, which is why this research trial is particularly important. 

 

What are the aims of this study?

The trial aims to determine:

  • if planned delivery at 38 can reduce problems for the mother without causing problems for the baby, compared with monitoring the pregnancy until at least 40 weeks.
  • whether planned delivery at 38 weeks reduces the need for Caesarean delivery and the risk of stillbirth, compared with monitoring the pregnancy until at least 40 weeks.

The research team are also interested in finding out if there is any link between the two different times of delivery for the baby and how well they perform at school as a child later in life.   

 

What will the researchers do?

The WILL trial will run for 3 years across 30 UK hospitals. In total, 1080 women will take part so that the study is large enough to show whether there are differences between the two groups of women and babies. Women will be asked to take part if they have reached 36 weeks of pregnancy and have high blood pressure (without other current problems). Women will be randomly put into one of two treatment groups: one for planned delivery at 38 weeks, by labour induction or elective Caesarean section as would normally be done in their hospital; the other group will be monitored until at least 40 weeks, and will start labour naturally unless a medical problem develops. 

The women continuing pregnancy to 40 weeks gestation will have the same care as they would usually have in the NHS, and the baby will be delivered early if there are signs of problems before 40 weeks. Doctors and midwives will provide normal care before and after birth for all women in the trial. The safety of women and babies in the trial will be carefully monitored. The research team will also ask women if they can link medical maternity records with their child’s school test results in the future to check whether there are any links between the timing of delivery and educational performance.

The research team is supported by a Parent Advisory Group that Sands has helped to establish. The group will oversee the running of the research project, giving parents the opportunity to work with researchers to ensure that the study runs as smoothly as possible and that its findings will be clearly communicated to other parents and families.  

 

What do we expect the study to find?

We anticipate that the results of the trial will help the growing number of women with high blood pressure and their midwives and doctors make decisions about timing of delivery, with the overall aim of reducing the number of health problems for women and babies and the number of stillbirths.

 

Additional information:

Lead researcher – Professor Laura Magee

Institution – King’s College London

Funder – National Institute for Health Research (NIHR)

Duration – May 2018 - July 2022

 

For more information please visit the WILL study website.

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