The numbers are good and the conclusions cautious. In 105 women studied twice, obstructive sleep apnea went from 10.5% in the first trimester to 26.7% in the third. In 3,705 first-time mothers, sleep-disordered breathing was found in 3.6% early and 8.3% in midpregnancy, and carried about twice the adjusted odds of preeclampsia (1.94 and 1.95) and nearly three times those of gestational diabetes (3.47 and 2.79). Frequent snoring, chronic high blood pressure, age, body mass index and neck size were the strongest predictors. These are associations from observational studies. Snoring that is new, nightly or comes with gasping is worth raising with your midwife or obstetrician.
Pregnancy changes how you sleep, and for some women it changes how they breathe while asleep. The worry usually arrives at 2 a.m.: a partner says the snoring has started, or a woman wakes with a dry mouth and a headache and a half-remembered article about blood pressure. This page gives the numbers as they are, which are firmer than most of the internet and gentler than the headlines.
It is information, not a diagnosis. Anything about your own pregnancy belongs with your midwife or obstetrician.
Sleep apnea and pregnant women: how common it becomes
The prevalence rises as pregnancy advances. A prospective study at the University of Pennsylvania followed 105 pregnant women who each had an overnight sleep study in the first and third trimesters. The average apnea-hypopnea index rose from 2.07 to 3.74 events per hour. Obstructive sleep apnea was found in 10.5% of the women in the first trimester and 26.7% in the third. Among women who did not have it at the start, higher first-trimester body mass index and older age were linked to developing it.
Pien GW, Pack AI, Jackson N, Maislin G, Macones GA, Schwab RJ. Risk factors for sleep-disordered breathing in pregnancy. Thorax 2014. PMID 24262432
A far larger study used in-home sleep tests: 3,705 women expecting their first baby, tested in early pregnancy (6 to 15 weeks) and in midpregnancy (22 to 31 weeks). Sleep-disordered breathing, defined as 5 or more events per hour, was present in 3.6% early and 8.3% in midpregnancy. The two studies differ in who was enrolled, how events were counted and when the third test fell, which is why the percentages do not match. What they share is the direction: it increases.
Who is at higher risk during pregnancy
The same large study, called nuMoM2b, asked which factors predicted sleep-disordered breathing. At each time point, frequent snoring (three or more nights a week), chronic high blood pressure, older age, higher body mass index, a larger neck and higher systolic blood pressure were the strongest. A model using just three of them, age, body mass index and frequent snoring, predicted sleep-disordered breathing in early pregnancy well (area under the curve 0.870) and new onset in midpregnancy somewhat less so (0.809). The authors suggested the models could help screening.
Louis JM, Koch MA, Reddy UM, Silver RM, Parker CB, Facco FL, Redline S, Nhan-Chang CL, Chung JH, Pien GW, Basner RC, Grobman WA, Wing DA, Simhan HN, Haas DM, Mercer BM, Parry S, Mobley D, Carper B, Saade GR, Schubert FP, Zee PC. Predictors of sleep-disordered breathing in pregnancy. Am J Obstet Gynecol 2018. PMID 29523262
One thing stands out. Snoring is on the list of predictors, and it is the one factor a person or a partner can notice. A woman with no other risk factors who has started snoring most nights is exactly the pattern the model leans on. Snoring while pregnant covers what is ordinary and what is worth flagging.
Snoring that starts in pregnancy
A separate cohort looked at timing. Researchers screened 1,719 women in the third trimester at a tertiary center. Thirty-four percent reported habitual snoring, and 25% reported pregnancy-onset snoring, which means it began during the pregnancy. After adjusting for confounders, pregnancy-onset snoring was independently associated with gestational hypertension (odds ratio 2.36, 95% CI 1.48 to 3.77), whereas snoring that predated the pregnancy was not. The authors concluded that new-onset snoring is a strong risk factor for gestational hypertension and preeclampsia, and that simple screening may be useful.
O'Brien LM, Bullough AS, Owusu JT, Tremblay KA, Brincat CA, Chames MC, Kalbfleisch JD, Chervin RD. Pregnancy-onset habitual snoring, gestational hypertension, and preeclampsia: prospective cohort study. Am J Obstet Gynecol 2012. PMID 22999158
Habitual snoring was self-reported, so some of it will have been mislabeled in both directions. Still, the finding makes sense of why a partner saying "you have started to snore" is a fair thing to mention at a prenatal visit.
What sleep apnea in pregnancy is linked to
In the nuMoM2b cohort, the women and their care providers did not see the sleep-test results, so the results could not have changed anyone's care. After adjustment for confounders, sleep-disordered breathing was independently associated with preeclampsia (adjusted odds ratio 1.94 with the early test and 1.95 with the midpregnancy test) and with gestational diabetes (3.47 and 2.79). Overall, preeclampsia occurred in 6.0% of the women, hypertensive disorders of pregnancy in 13.1% and gestational diabetes in 4.1%. The higher the apnea-hypopnea index, the stronger the link.
Facco FL, Parker CB, Reddy UM, Silver RM, Koch MA, Louis JM, Basner RC, Chung JH, Nhan-Chang CL, Pien GW, Redline S, Grobman WA, Wing DA, Simhan HN, Haas DM, Mercer BM, Parry S, Mobley D, Hunter S, Saade GR, Schubert FP, Zee PC. Association Between Sleep-Disordered Breathing and Hypertensive Disorders of Pregnancy and Gestational Diabetes Mellitus. Obstet Gynecol 2017. PMID 27926645
A systematic review and meta-analysis of 31 studies points the same way. Maternal sleep-disordered breathing was associated with gestational hypertension or preeclampsia (pooled adjusted odds ratio 2.34, from 5 studies) and gestational diabetes (1.86, from 5 studies). All the studies were observational, and the authors said large prospective and interventional studies were needed to understand the relationship.
Pamidi S, Pinto LM, Marc I, Benedetti A, Schwartzman K, Kimoff RJ. Maternal sleep-disordered breathing and adverse pregnancy outcomes: a systematic review and metaanalysis. Am J Obstet Gynecol 2014. PMID 23911687
Read that last sentence slowly. Association is not cause: women who have both could share an underlying factor such as weight or blood pressure, which the studies adjust for but cannot remove. Nor does it say that treating sleep apnea in pregnancy prevents these problems. Treatment decisions in pregnancy sit with your obstetric and sleep specialists.
Does it go away after the baby is born?
For some, it seems to. A follow-up study retested women 1 to 2 years after delivery. Of 18 women with complete data, the 11 who had gestational hypertension saw their mean respiratory disturbance index fall from 12.0 in pregnancy to 2.9 afterwards, which was no different from the 7 healthy women. The authors read that as a sign that the physical changes of pregnancy may play a role in the sleep apnea some women with gestational hypertension have. With 18 women, it is a hint, not a forecast for any one person.
Reid J, Glew RA, Skomro R, Fenton M, Cotton D, Olatunbosun F, Gjevre J, Guilleminault C. Sleep disordered breathing and gestational hypertension: postpartum follow-up study. Sleep 2013. PMID 23633754
Why a checklist is not enough, and what a recording adds
You might hope that a questionnaire would settle it. A systematic review and meta-analysis found otherwise: of the screening tools used in pregnancy, the Berlin questionnaire had a pooled sensitivity of 0.66 and specificity of 0.62, and the Epworth Sleepiness Scale 0.44 and 0.62. The authors concluded that both performed poorly and that a new screening questionnaire is needed. In early pregnancy and in high-risk pregnancies, the Berlin questionnaire's sensitivity was lower still (0.47 and 0.44).
Tantrakul V, Numthavaj P, Guilleminault C, McEvoy M, Panburana P, Khaing W, Attia J, Thakkinstian A. Performance of screening questionnaires for obstructive sleep apnea during pregnancy: A systematic review and meta-analysis. Sleep Med Rev 2017. PMID 28007402
That is where a few nights of audio can help in practice: not as a test, but as concrete information to bring. How many nights a week do you snore, how loud, and are there gaps followed by a gasp? Frequent snoring is the one predictor in the studies that you can count. SleepTrace listens through the phone's microphone, marks snoring episodes and keeps clips you can play to your care team (the free plan plays back 3 clips a month, Premium has no limit). It also shows a breathing screening with a risk level and an average index. It is not a medical device, and it cannot diagnose sleep apnea or say anything about oxygen or blood pressure.
What to bring to a prenatal appointment
A clinician will want to know a few things, and most of them you can collect without equipment. How many nights a week you snore, and whether that is new since you became pregnant (the pregnancy-onset question). Whether a partner has seen pauses or gasping. How you feel on waking and how sleepy you are by day. Your own blood pressure readings if you have been taking them, and your weight trend. A short clip of the loudest part of a night, if you recorded one.
None of that makes a diagnosis. It saves the appointment from starting at zero, and it turns a vague "I think I snore more" into something specific enough for your care team to decide whether a sleep test is warranted.
If you are pregnant and snore most nights, wake gasping, have been told you stop breathing, or are very sleepy during the day, tell your midwife or obstetrician at your next contact. If anything about your pregnancy worries you, such as headaches that will not go away, vision changes or sudden swelling, contact your care team promptly instead of waiting for your next visit.
For the broader picture of who tends to develop sleep apnea, see Sleep apnea risk factors; for the test itself, see How to test for sleep apnea at home.
Frequently asked questions
It becomes more common as pregnancy goes on. In a study of 105 women who had overnight sleep tests in the first and third trimesters, obstructive sleep apnea rose from 10.5% to 26.7%. In a much larger home-testing study of 3,705 first-time mothers, sleep-disordered breathing was found in 3.6% of women early on and 8.3% in midpregnancy. Different cohorts, definitions and timing explain part of the gap.
Studies link it to higher odds of high blood pressure disorders and gestational diabetes in the mother. In a meta-analysis of 31 studies, pooled adjusted odds were 2.34 for gestational hypertension or preeclampsia and 1.86 for gestational diabetes. These are observational associations and the authors called for larger prospective and interventional studies. It does not mean every woman who snores will have a complication.
It may. In 1,719 women screened in the third trimester, 34% snored habitually and 25% had snoring that began in the pregnancy. Pregnancy-onset snoring, but not snoring that predated the pregnancy, was independently associated with gestational hypertension (odds ratio 2.36). It is a signal to mention to your care team, not a diagnosis.
In one small follow-up of 18 women, the 11 who had gestational hypertension had a mean respiratory disturbance index that fell from 12.0 in pregnancy to 2.9 one to two years after, similar to healthy women. That suggests pregnancy itself played a part, but the group is small and cannot predict what will happen in your case.
A recording can show how often you snore and whether there are gaps and gasps, which is useful to bring to an appointment. It cannot diagnose sleep apnea. Screening questionnaires also perform poorly in pregnancy, so if you or your partner notice loud snoring, pauses or heavy daytime sleepiness, ask your care team about proper testing.
SleepTrace is a wellness app, not a medical device. This article is general information, not medical advice. If your symptoms are frequent, severe or worrying, please talk to a doctor.
The large studies show an association, not a verdict, so the practical step is finding out what your nights contain. SleepTrace records sound only, saves snoring clips, marks possible breathing pauses with a time and estimates your sleep phases. It screens and does not diagnose; your care team decides what comes next.
Hear your own night. SleepTrace turns a night of audio into your sleep phases, the sounds you made, and how it all trends. Works without a wearable, better with one. Your phone on the nightstand is enough to start. Get it for iPhone or Android →