The European Respiratory Journal just carried an article on the topic of snoring in pregnant women, especially in the third trimester. It notes that a research team in Scotland discovered the phenomenon is caused by a narrowing of the upper airways during pregnancy. This is obviously a problem for the woman's partner and may cause tension between them at the very time when she most needs support, but it can also lead to health problems if the snoring becomes severe. Chronic snoring is known to be linked with respiratory problems at night, which can lead to daytime sleepiness and raise blood pressure; this can endanger the fetus as well as the mother.

The prospective study at Edinburgh University examined 100 women who were at least six months pregnant and 100 control women of the same age range. The study confirms that women in the last trimester of pregnancy are more than twice as likely to snore (41%) than their non-pregnant counterparts (17%). It also shows that the percentage of snorers, among the pregnant subjects, rises from 12% before pregnancy to 41% during the third trimester.

However, the phenomenon proves to be reversible, since the proportion falls back to 18% three months after delivery, which is close to the proportion of snorers in the control group. In addition, sleep apnea (frequent, short cessation in breathing during sleep) was present in 14% of the pregnant subjects and only 3% of the control group.

The researchers also looked into the causes of snoring during pregnancy. Pregnant snorers were found to have significantly higher pre-pregnancy weight and body mass index than the non-snorers. Additionally, the pregnant women who snored tended to have a greater neck circumference, on average one centimeter more than that found in the non-snorers.

The Scottish team's most interesting discovery, however, concerned the upper airways. Using an original soundwave method, they conducted five successive measurements of the upper airways while the women were seated and laying on their backs and sides. During pregnancy, their upper airways were narrower than when measured after delivery or compared to the control group. Since the measurements were conducted when the subjects were awake, it is likely that relaxation of the dilatory muscles during sleep would narrow the airways even more.

Fat can infiltrate the pharyngeal muscles or be deposited in the soft tissue of the neck and around the upper airways, which can increase neck size and narrow the airways. The researchers said pregnant women who snore should be reassured by explaining that it will probably end after delivery. Sleeping on one's side can reduce snoring, but many pregnant women do that anyway. In extreme cases, devices kept in the mouth or positive airway pressure masks may be used during sleep to minimize snoring.

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