Ask An Expert Question:
“Please check to see what bearing sleep apnea has on the placenta of the mother. I have a family history of sleep apnea and now need CPAP and in pregnancy was known to snore. If this could affect the way the placenta's circulation was established, I wonder if this is a common but unrecognized problem.”
Evidence for a contribution to preeclampsia from sleep-disordered breathing has been emerging for a few decades. The earliest research appears about 20 years ago, and the evidence of a link has been gradually accumulating, including through research we funded in 2007. Women with sleep apnea are known to be at higher risk of chronic hypertension, which raises the risk for preeclampsia, and are at higher risk of preeclampsia, even if they are not chronic hypertensives. Some of the molecules that produce the symptoms of preeclampsia are produced in greater amounts when the placenta is short of oxygen, so there is a plausible biological mechanism - a way for sleep apnea to contribute to preeclampsia in susceptible women. However, sleep apnea is also very common in all pregnant women, and becomes more frequent as we gain weight (so, in late pregnancy it is even more common than in early pregnancy.) Recent reviews say obstructive sleep apnea happens in about one in five obese pregnant women. But not all women with sleep apnea develop preeclampsia. Like obesity itself, it is a risk factor that can contribute to the likelihood of developing placental complications. In women who are at high risk of obstructive sleep apnea, preeclampsia is around 2 to 3 times more likely to occur. It seems like prescribing CPAP (Continuous Positive Airway Pressure machine that keeps air easily flowing into the lungs during sleep) might lower the risk, but no one knows if this will actually prevent preeclampsia in some women. A clinical trial is currently recruiting patients to investigate if CPAP helps lower the rate of preeclampsia: https://clinicaltrials.gov/ct2/show/NCT03487185 Some other trials into this question have shut down for lack of timely enrollment when research funding ran out. Women who notice that they have begun to snore in pregnancy, who have a family history of sleep apnea, or who are waking up in the morning still tired (or with other symptoms of apnea) should mention this to their care providers, who may want to evaluate them for sleep apnea that can be treated.
About Caryn Rogers
Senior Science Writer
Caryn Rogers is the senior science writer at the Preeclampsia Foundation. As a community moderator, she has dedicated 15 years to creating clear, understandable explanations of the science underpinning preeclampsia so that women can use this knowledge to protect their own interests. Published in Journal of Medicine and Philosophy and in Pregnancy Hypertension, Caryn uses her experience with philosophy of evolutionary medicine to support the Preeclampsia Foundation’s mission. She developed preeclampsia with severe features at 33w in 2002. After a week in NICU, her son recovered well. Her daughter was born at 39w after a normotensive pregnancy.