Breathing during sleep may change during pregnancy: as a pregnancy unfolds, there may be a clear progression from soft to loud snoring, and even pauses or disruptions of breathing that characterize a condition called sleep apnea. Sleep apnea as it occurs in pregnancy has clearly-recognized risk factors, symptoms, and treatments.
Risk Factors for Sleep Apnea in Pregnancy
Snoring progressively increases in severity and frequency during pregnancy, and when the airway is further disturbed, sleep apnea may occur. Sleep apnea is characterized by pauses in breathing during sleep that last for at least 10 seconds, and that are associated with awakenings (called arousals), and drops in the oxygen levels of the blood (called desaturations). Sleep apnea may have significant consequences, and certain women may be at higher risk for developing the condition.
Fortunately, the overall risk of developing sleep apnea during pregnancy is relatively low, due to a couple of factors: first, levels of progesterone are high during pregnancy—an apparently protective state, since the hormone activates muscles that dilate the airway. In addition, progesterone increases the brain’s responsiveness to carbon dioxide levels, and the delivery of oxygen to the body’s tissues also improves with increased heart rate and enlargement of the peripheral blood vessels. Second, due to physical discomfort associated with late pregnancy, less time is spent sleeping on the back, which is associated with an increased risk of sleep apnea.
Sleep apnea may nevertheless occur. Although the precise prevalence is not known, it's estimated to affect 10% of pregnant women. Sleep apnea occurs more often in women who are overweight or obese, and excessive weight gain during pregnancy may also increase risk. Women with a large neck size also have more sleep apnea. In addition, nasal congestion due to high levels of progesterone can contribute to the condition. Lung volumes may be reduced due to pressure from the developing fetus, resulting in an increased breathing rate. Exposure to smoking is also a clear risk factor for developing sleep apnea.
The Symptoms of Sleep Apnea in Pregnancy
Women who are afflicted with sleep apnea in pregnancy develop symptoms that are similar to the condition when it occurs in other contexts. These symptoms include:
- Breathing pauses or shortness of breath in sleep
- Waking with choking, snorting, or gasping
- Excessive daytime sleepiness
- Frequent urination at night (nocturia)
The condition is likely under-diagnosed. It may be important to seek evaluation from a sleep specialist, especially after the sixth month of pregnancy, when symptoms may worsen. High-risk women with obesity, preeclampsia, gestational diabetes, and intrauterine growth retardation should be evaluated. This may include an overnight sleep study called a polysomnogram.
Treatment of Pregnancy-Related Sleep Apnea
It is important to treat pregnancy-related sleep apnea, as it can contribute to adverse consequences in both the mother and fetus. Sleep apnea is associated with gestational hypertension, diabetes, and unplanned Caesarian sections. It may also lead to fetal growth restriction and prolonged labor. Severely affected women may develop obesity hypoventilation syndrome.
After delivery and the ensuing loss of weight, sleep apnea will improve. Studies show that a measure of sleep apnea severity called the apnea-hypopnea index (AHI) normalizes after delivery.
During pregnancy, it can be helpful for women to sleep on their sides. The gold standard treatment is the use of continuous positive airway pressure (CPAP). In severe cases with associated obesity, or in twin pregnancy, bilevel therapy may be employed. The pressure settings used in these treatments will need to be adjusted during the pregnancy. As natural weight gain occurs, the pressure will likewise need to be increased. In rare cases, the use of supplemental oxygen, or a surgical procedure called a tracheostomy, may be required.
If you feel you have signs or symptoms that are suggestive of sleep apnea during pregnancy, you should contact your doctor to discuss arranging the needed tests and treatments to help you rest and breathe easier.
Kryger, MH et al. "Principles and Practice of Sleep Medicine." ExpertConsult, 5th edition, 2011, pp. 1576-1577.