Snoring during pregnancy is often attributed to tiredness or an incorrect sleeping position and thus is not taken seriously by many pregnant women. Indeed, mild snoring has little effect on one’s health. However, it is important to pay attention to the severe RDDS symptoms of a sleeping pregnant woman, such as snoring louder than 60 decibels, irregular snoring, breath-holding of different degrees and apnea.
Dangers of Snoring Induced by RDDS
Many people know that snoring is bad for their health, but they don’t fully realize the dangers of snoring due to RDDS in pregnant women. It can lead to drowsiness, fatigue, attention-deficit, headache, decline of work ability and other snoring sequelae; and, in more serious cases, it may also cause blood pressure rising, fetal development delays and other adverse consequences.
A study found  that RDDS is significantly related to gestational hypertension of pregnant women during the third trimester. In the snoring group, 12 percent of women had a hypertensive disorder complicating pregnancy, higher than that in non-snoring group (3.90%). RDDS can cause hypoxemia, hypercapnia, dysregulation of body fluids and nerves, and overexcitation of the sympathetic nervous system in pregnant women. In the interaction of all these factors, the pregnant woman’s blood pressure will rise.
Anoxia in pregnant women can lead to the heart rate decline of fetus, a rise in blood pressure and the decrease in respiratory movement. Long-term anoxia can also result in polycythemia of fetal blood, an increase of blood viscosity and intrauterine growth retardation (IUGR) .
In addition, another study showed that incidence of fetal premature delivery of snoring group in the first and second trimester was significantly higher than that of snoring group in third trimester and non-snoring group, and snoring during the first and second trimester was a risk factor for premature delivery according to the relative risk (RR) analysis . Thus, it can be inferred that the longer snoring history during pregnancy it has, the greater the risk to the fetus it causes.
Causes of Snoring during Pregnancy
Data have indicated that the rate of snoring in the third trimester is 41 percent, compared with 17 percent in non-pregnant women of the same age, and it will recover to 18 percent three months after the delivery . The prevalence of snoring in pregnant women is largely due to the effects of multiple physiological changes during pregnancy.
During pregnancy, the pregnant woman’s expanding uterus will push up the diaphragm of the abdomen, reducing the space of her chest, leading to decreased ventilation function of the lungs and limited breathing, thus causing adverse effects on sleep. Furthermore, rising estrogen levels can make pregnant women in the third trimester appear nasal mucosal congestion and rhinitis, leading to a decrease in the openness of the nasal cavity . This may also explain why many pregnant women in the third trimester complain about the nasal congestion.
At the same time, with the increase in gestational age and weight, the pregnant woman will gain more subcutaneous fat in her neck, which will limit the reflex of the lower jaw and result in mechanical obstruction of tongue movement . Particularly in the supine position, the falling pharyngeal fat and neck fat will compress the airway, further aggravating the collapse and the occlusion of the airway . Among them, neck circumference is closely related to the incidence and the severity of snoring and RDDS in pregnant women. Compared with an abdominal circumference and a hip circumference, it is more sensitive to reflect the degree of obesity and upper airway condition in pregnant women. When the neck circumference is ≥ 36 cm, the incidence of snoring has increased significantly (P < 0.01) .
Nursing Is the Key to Prevent Snoring during Pregnancy
For snoring during pregnancy, prevention is much more important than treatment. For women who snore frequently before pregnancy, it is necessary to improve and treat the upper respiratory problems under the guidance of an otolaryngologist after examination. And those pregnant women who often feel nasal congestion during pregnancy can take local medication under the guidance of a doctor to relieve congestion and edema of the nasal mucosa. It should be noted that snoring during pregnancy is associated with obesity, so pregnant women should pay attention to weight control from the preparation period to the whole pregnancy.
Besides, if a pregnant woman often snores, it is recommended that family members carefully observe the rhythm, the sound and the breathing pauses of her snoring, and take her to the hospital for examination and treatment if any abnormalities are found.
 Pamidi S, Pinto LM, Marc I, et al. Maternal sleep disordered breathing and adverse pregnancy outcomes: a systematic review and meta-analysis[J]. Am J Obstet Gynecol, 2014, 210(1): 52
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 Li Meili, Cai Xiaohong, Ni Liyan, Zhang Huangai, Yu Chenyi, Xuan Miaoyan, Xie Yupeng, Lyu Jieqiang. Effect of Snoring during Pregnancy on Fetal Growth and Development [J]. Journal of Medical Research, 2011, 40 (03): 51-55
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