Studying sleep apnoea in obese pregnant women

Obese pregnant women are more likely to suffer from sleep apnoea, where breathing pauses during sleep. Our scientists are investigating how common sleep apnoea is, and what effect it has on mother and baby.
  • Authors list

    Dr Emma Johns, Professor Rebecca Reynolds, Professor Fiona Denison, Dr Renata Riha

    Start date: February 2018
    End date: April 2021

  • Research centre

  • Research status

    Completed projects

Why do we need this research?

Being obese increases the chances of complications during pregnancy. One medical condition linked to obesity is sleep apnoea, where a person stops breathing during sleep for short periods of time. These episodes can lead to a decrease in oxygen in the blood.

Scientists believe that sleep apnoea in obese pregnant women might contribute to pregnancy complications such as gestational diabetes, pre-eclampsia, premature birth and stillbirth. However, we don’t know enough about this to be certain. We also don’t know what proportion of obese pregnant women have sleep apnoea, and how many women develop sleep apnoea in pregnancy who did not have it previously. This is preventing us from helping these women.

What happened in this project?

Researchers funded by Tommy’s set up the Sleep Easy study to better understand the impact and extent of sleep apnoea during pregnancy. The study included 77 pregnant women; some who were severely obese – with a BMI of 40 or above – and some whose weight was considered to be healthy. The women took part in two overnight sleep tests, during which they were asked to wear equipment that could detect sleep apnoea or other sleep breathing disorders. These tests were carried out in mid pregnancy (between 12 and 22 weeks) and late pregnancy (between 32 and 38 weeks). The women also answered sleep questionnaires and donated blood samples and their baby’s placenta after birth.

Our researchers found that 38% of the severely obese pregnant women suffered from sleep apnoea in mid pregnancy, while 50% had sleep apnoea in late pregnancy. Among the women of healthy weight, these figures were 3% and 9%, respectively. The team found that an existing screening tool was good at predicting which women were most likely to suffer from sleep apnoea during pregnancy.

Our scientists also studied placenta samples from 20 severely obese women – 11 with sleep apnoea and nine without sleep apnoea – in an attempt to understand more about the link between sleep apnoea and pregnancy complications. The team checked which genes were active in the placenta cells from the two groups of women and found that the pattern of activity was actually very similar.

What difference will this project make?

This project has shown that a substantial number of obese women suffer from sleep apnoea during pregnancy. Despite not being routinely screened for, our researchers believe that sleep apnoea contributes towards pregnancy complications in these women. If this is the case, it may be possible to treat the sleep apnoea and therefore reduce the chances of these women experiencing complications during pregnancy.

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