Screening tools for OSA in pregnancy fall short

Obstructive Sleep Apnea or OSA is often not the first thing we think about with pregnancy, but when an expecting mother has OSA she is prone to a slew of pregnancy-related complications. OSA is caused by obstruction of the upper airway during sleep that causes a cessation in breathing and thus decreases oxygen saturation. A group of researchers at the Washington University School of Medicine recently conducted a study to see if our current OSA screening tools can detect OSA in pregnant women. 

The study participants were 248 women in the third trimester of pregnancy. The women took 6 different OSA screening surveys and then did the gold standard for diagnosing OSA: overnight sleep monitoring. 88% of women did not have OSA based on their sleep monitoring and 12% were diagnosed with OSA.  The women with OSA as shown by their overnight sleep monitoring were more likely to have chronic high blood pressure, high blood pressure related to pregnancy, diabetes diagnosed before pregnancy, asthma, and preeclampsia. They also had a higher BMI and larger neck circumference on average than women who did not have OSA.

Unfortunately, none of the screening tools tested were very good at detecting OSA in pregnant women. The proportion of women with OSA who were correctly identified as having OSA (sensitivity) ranged from 0.5 to 0.7. The proportion of women who do not have OSA who were correctly diagnosed as not having OSA (specificity) ranged from 0.5 to 0.8. This means that the screening tools are missing about half to one-third of women with OSA.

The good news? The researchers broke down the screening tools into their individual questions to see which questions best predict who has OSA. Here were the winners: Do you snore, especially loudly and frequently?  Do you stop breathing during sleep? Do you have a BMI greater than 35? Is your neck circumference greater than 40cm? Do you awake from sleep with a choking sensation? Are you frequently aroused from sleep? A yes to these questions indicated a higher risk of OSA for pregnant women. 

For now, health care providers caring for pregnant women must be on the look out for signs and symptoms of OSA so they can offer treatments and monitor for the pregnancy complications linked to OSA. In the future, we can hope for a better screening tool to identify which pregnant women are at the highest risk of OSA.