Pregnant Women's Snoring May Not Affect Fetal Outcomes


WASHINGTON — Pregnant women's snoring has no apparent negative impact on fetal outcomes, despite some differences in fetal umbilical arterial blood gases, based on data from two studies including more than 600 women.

Previous research has suggested that habitual snoring in pregnant women may be a risk factor for poor fetal outcomes, but the available data were primarily from case studies, said Dr. Alexandra Bullough and Louise O'Brien, Ph.D., of the University of Michigan in Ann Arbor.

As part of a larger study of the impact of sleep-disordered breathing (SDB) on both maternal and fetal outcomes, the researchers recruited 380 women aged 18 years and older in the third trimester of singleton, uncomplicated pregnancies to complete sleep questionnaires. This study is the first known to examine the impact of maternal SDB on fetal outcomes after delivery, based on umbilical blood gas values for arterial pH, partial pressure of carbon dioxide (PCO2), HCO3, and base excess.

Overall, 129 women met the criteria for SDB, and they were compared with 251 nonsnoring controls. The women with SDB averaged a significantly higher body mass index than controls both before pregnancy (35 kg/m

In this study, there were no significant differences between the SDB and control groups in average measures of arterial pH (7.3 vs. 7.3), PCO2 (54.4 mm Hg vs. 57.4 mm Hg), HCO3 (23.6 mmol/L vs. 24.4 mmol/L), and base excess (−1.82 mmol vs. −1.85 mmol).

These preliminary findings suggest that maternal SDB may not be associated with adverse fetal outcomes. But the study is ongoing, and data that haven't yet been fully analyzed suggest a possible association. “We're not sure how [maternal SDB] might affect fetal outcome,” Dr. Bullough said in a poster presentation at the annual meeting of the Society for Obstetric Anesthesia and Perinatology.

Habitual snoring was not significantly associated with low birth weight or Apgar scores, based on a second study of 429 women with uncomplicated singleton pregnancies. In this study, also conducted by Dr. O'Brien and Dr. Bullough, 35% of the women reported habitual snoring (at least 3 nights each week) and 25% were obese (with a BMI of at least 30 kg/m

Overall, habitual snoring was not significantly associated with low birth weight and Apgar scores. These results held after controlling for variables including maternal diabetes, age, and race. Only the gestational age at delivery and the mother's BMI before pregnancy were independent significant predictors of birth weight and 1-minute Apgar scores, and only gestational age at delivery was an independent and significant predictor of 5-minute Apgar scores. Regardless of sleep apnea status, “women with high BMI were going to have bigger babies,” Dr. Bullough said.

These results contrasted with previous studies suggesting that maternal sleep apnea may predict poor infant outcomes, and more research is needed to evaluate the association.

The researchers said they had no financial conflicts to disclose.

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