Oct. 1, 2010 -- Getting too much or too little sleep during the first trimester may increase a woman’s risk of developing elevated blood pressure and its related complications later in pregnancy, according to a new study.
Pregnancy-induced high blood pressure is a symptom of preeclampsia, a serious condition that is also linked to excess protein in urine. It typically occurs after the 20th week of pregnancy. Untreated, preeclampsia increases a woman's risk for life-threatening eclampsia during pregnancy.
Women who slept six hours or less per night in their first trimester had systolic pressure that was 3.72 points higher in the third trimester than their counterparts who slept nine hours a night. Researchers say nine hours of sleep is normal and appropriate during pregnancy. This number is higher than the usually recommended seven to eight hours a night because pregnant women tend to have greater sleep needs. The study appears in the Oct. 1 issue of the journal Sleep.
Increases in Blood Pressure Seen During Third Trimester
Women who slept 10 hours or more per night had a systolic pressure that was 4.21 points higher in the third trimester than women who got nine hours of sleep early in their pregnancy. Systolic blood pressure is the upper number in a blood pressure reading and refers to the pressure in the arteries when the heart beats. Similar increases were seen for diastolic blood pressure (the lower number in a blood pressure reading that measures the pressure in the arteries between heartbeats).
Although these numbers are small, they could be enough to push certain women's blood pressures into the high range.
Women who slept nine hours a night during early pregnancy had a mean systolic blood pressure of 114 in their third trimester. Pregnant women who slept six or less hours per night during their first trimester had a systolic pressure of 118.04. Women who slept for 10 hours a night or more early on in their pregnancy had a systolic pressure of 118.90, the study showed.
More Study Needed
It is not fully understood exactly how too little sleep or too much sleep and blood pressure during pregnancy are connected.
"Moving forward, large-scale sleep studies should include pregnant cohorts so that health care providers and mothers-to-be can more fully appreciate the health risks of insufficient sleep," Michele A. Williams, ScD, a professor of epidemiology in the School of Public Health at the University of Washington in Seattle and the co-director of the Center for Perinatal Studies at Swedish Medical Center in Seattle, says in a news release.
In the study, more than 1,200 healthy pregnant women were asked about their sleep habits since becoming pregnant at 14 weeks into their pregnancy. Overall, 20.5% of women said they slept nine hours per night, 55.2% of women slept seven to eight hours per night, and 13.7% slept six or fewer hours per night, and 10.6% of women slept 10 hours or more per night early in their pregnancy.
More than 6% of women were diagnosed with preeclampsia or pregnancy-induced high blood pressure during the study. Women who got less than five hours of sleep per night were almost 10 times more likely to develop preeclampsia, the study showed.
Good Sleep Hygiene in Pregnancy a Must
"This was a rather groundbreaking study," says Michael Breus, PhD, author of Beauty Sleepand the clinical director of the sleep division for Arrowhead Health in Glendale, Ariz.
"It is a great start and one of the first, if not the first, study to look at how sleep can have an effect on blood pressure during pregnancy -- specifically first-trimester sleep," he says.
The study points to the importance of good sleep hygiene in pregnancy, he says.
For starters, "you need to be careful about how much weight you are gaining," he says. Some pregnant women may develop sleep apnea, a sleep disorder marked by pauses in breathing while asleep. "If your bed partner notices that you have started snoring or light breathing, call your doctor for evaluation," he says.
Exercise is known to improve sleep quality. "If you are comfortable and your doctor has said it is OK to exercise during pregnancy, moderate exercise will help with overall sleep," he says. Cutting back on caffeine is also important during pregnancy, and as a means of improving sleep.
"Aim for a reduction if not elimination of caffeine during pregnancy," he says. Also, make sure your mattress is supportive during pregnancy.
"If it is too firm, consider a mattress topper to make it softer," he says.
Avoid reading any scary pregnancy or childbirth stories right before bed, Breus says.
"Read these articles in the morning, not in the evening, because all that will do is prevent you from sleeping," he says.
Manju Monga MD, the Berel Held Professor and the division director of maternal-fetal medicine at the University of Texas Health Sciences Center in Houston, says that pregnancy and sleep issues often travel together. "Some women get up and use the restroom all night long, or find it hard to get in a comfortable position when sleeping," she says.
"Taking naps during the day can also make it harder to get a good night's sleep," she says.
Her advice? "Do something relaxing and not stressful relaxing before bed," she says. And "tell your obstetrician if you are having problems with sleep."