By Lisa Rapaport
(Reuters Health) - Although doctors often tell pregnantwomen it's safest to sleep on their left side, a new studysuggests sleeping in other positions may not be a problem.
Researchers examined data on outcomes for 8,709 pregnantwomen who completed at least one sleep questionnaire before theyreached 30 weeks' gestation. Overall, 1,903 women, or 22%,experienced serious complications like dangerously high bloodpressure, stillbirth or a newborn small for its gestational age.
Women who slept on their right side or on their back were nomore likely to experience serious complications than women whoslept on their left side, the study found.
These results should reassure many pregnant women who mightworry about harming their baby by sleeping on their back, ormoving into this position during the night, said Dr. RobertSilver, lead author of the study and chair of obstetrics andgynecology at the University of Utah School of Medicine in SaltLake City.
"There is downside to encouraging the avoidance of supine(back) sleep," Silver said by email.
"Some women may have trouble sleeping on their left side andthey cannot control movement during sleep," Silver added. "Evenwith careful messaging, there is potential to increase anxietyin women who wake up on their backs and guilt, shame andself-blame in women suffering adverse pregnancy outcomes such asstillbirth."
Previous studies have linked sleeping on the back or rightside to an increased risk of serious pregnancy complicationsbecause these positions may compress blood vessels supplying theuterus, researchers note in Obstetrics and Gynecology.
Women in the current study were more likely to have seriouspregnancy complications when they were overweight or obese,smoked or had high blood pressure or diabetes prior topregnancy.
Neither the positions women were in when they went to sleepor woke up, nor the positions they might move to during thenight appeared to impact the risk of complications.
Researchers also looked at objectively-measured sleeppositions for a subset of women who underwent home sleep studiesfor nighttime breathing problems. For these women, there alsowas no meaningful difference in the risk of pregnancycomplications based on whether they slept on their back morethan half of the time, or less often.
The study wasn't designed to prove whether or how sleeppositions might directly impact pregnancy outcomes. It alsodidn't look at the connection between sleep position andcomplications in the final weeks of pregnancy.
One limitation of the study is that there were only about adozen stillbirths – which may have been too few to detectmeaningful differences in this outcome based on sleep position,the study team notes.
Even so, women should be reassured by the results, said Dr.Nathan Fox, a clinical professor at the Icahn School of Medicineat Mount Sinai and vice president at Maternal Fetal MedicineAssociates in New York City.
"Pregnant women should sleep in the position that they findmost comfortable," Fox, who co-wrote an editorial accompanyingthe study, said by email. "For the few that do experiencecomplications of pregnancy they should be reassured that it wasnot due to their sleeping position."
SOURCE: https://bit.ly/2mbNRwO and https://bit.ly/2kfKVP9Obstetrics and Gynecology, online September 10, 2019.