DENVER — Obstructive sleep apnea is far more common during pregnancy than most physicians realize and in its more severe forms can jeopardize the fetus, Meir H. Kryger, M.D., said at a satellite symposium held in conjunction with the annual meeting of the Associated Professional Sleep Societies.
“I've had cases of sleep apnea in pregnant women who actually before diagnosis had several spontaneous abortions. I have no doubt that in some cases the baby was lost when it became very, very hypoxic,” added Dr. Kryger, professor of medicine and director of the sleep disorders center at the University of Manitoba, Winnipeg.
The treatment for obstructive sleep apnea in pregnancy is continuous positive airway pressure (CPAP). It's considered safe for both mother and fetus.
The prevalence of habitual snoring—that is, snoring nearly every night—climbs from 4% in nonpregnant women to 14%–23% during pregnancy.
The increase during pregnancy is believed to be due to weight gain coupled with hormonally induced changes in the elasticity of the pharyngeal airway and other tissues.
“Sleep apnea is actually quite common in pregnant women. I don't know why more doctors don't pick it up,” Dr. Kryger said. “[Physicians], I think, need to learn a great deal more about sleep and its problems.”
He advises routinely performing polysomnography in pregnant heavy snorers (especially if they are also observed to stop breathing), treating with CPAP those who meet the criteria for obstructive sleep apnea, and repeating the sleep lab testing postpartum.
The reason Dr. Kryger advocates an aggressive approach is the documented adverse effects of heavy snoring in pregnancy. He pointed to a Swedish study conducted several years ago that highlighted the implications of heavy snoring during pregnancy.
The study by Karl A. Franklin, M.D., Ph.D., a pulmonologist at University Hospital, Umeå, and his coworkers involved 113 habitual snorers and 289 infrequent or nonsnorers. All had singleton pregnancies. On their delivery day, they and their partners completed a detailed questionnaire focusing on snoring, daytime tiredness, and witnessed sleep apneas.
Habitual snoring proved to be associated with significantly higher rates of preeclampsia, new-onset hypertension, facial edema, and edema at other sites. Heavy snoring was also associated with significantly higher rates of babies who were small for their gestational age and of low 1- and 5-minute Apgar scores.
“One of the really important things to remember is that if a woman has sleep apnea and she delivers a baby, she's going to be very, very sleepy and will have a great deal of difficulty caring for a newborn,” Dr. Kryger said.
In fact, this sleep disturbance and the resultant feelings of maternal inadequacy due to profound fatigue can be a factor in postpartum depression, the most common complication of childbearing, he continued.
The Swedish study is one of several that have identified obesity as the major risk factor for sleep apnea in pregnancy. Habitual snorers in pregnancy were considerably heavier before pregnancy and gained more weight during pregnancy than did the infrequent snorers.
The link between habitual snoring and pregnancy-induced hypertension reported by Dr. Franklin and his coworkers has also been found by others. Preeclampsia has been associated not only with upper airway narrowing, snoring, and frequent arousals from sleep, but also with restless legs syndrome and other periodic limb movements.
“A pregnant woman who develops hypertension or protein in the urine may need to have a sleep evaluation. She may have either asymptomatic snoring or something more serious,” Dr. Kryger said.
The good news, only recently documented for the first time, is that sleep-disordered breathing arising in late pregnancy often improves following parturition, according to Dr. Kryger, who pointed to a study by Natalie Edwards, Ph.D., and her coworkers at the University of Sydney (Australia).
In 10 women referred for sleep-disordered breathing in the third trimester, the investigators found that significant improvements in the apnea-hypopnea index and minimum arterial oxyhemoglobin saturation occurred in all 10 postnatally. Peak arterial blood pressure responses to apnea also dropped markedly (Sleep 2005;28:737–41).