Sleep in Pregnancy: Causes, Safety and What Can Really Help
Poor sleep belongs to pregnancy like the nausea at the start. The causes differ by trimester, some are treatable, others have to be endured. What physiology explains, which sleeping position the evidence supports, what can help with restless legs, which remedies are allowed and which are not, and when to seek a medical evaluation.
In my consultations I often hear the sentence "I sleep terribly, am I doing something wrong?" The honest answer is usually: no. Poor sleep in pregnancy is the rule, not the defect. Mindell 2015 surveyed 2427 pregnant women, 76 percent reported poor sleep quality. That is both reassuring and unsatisfying. Reassuring, because it is normal. Unsatisfying, because there is still something you can do. My job is to separate three things: what is physiological and simply part of it, what is treatable (restless legs with iron deficiency, sleep-disordered breathing, insomnia via CBT-I), and what demands safety (sleep aids, sleeping position). Safety first, then comfort. This spoke is deliberately phrased with caution, because in pregnancy no self-experiment outweighs the comfort of a calm night.
This spoke goes through the physiological causes by trimester, the evidence on sleeping position, the topic of restless legs and iron, the safety of sleep aids (what is allowed, what is not), sleep-disordered breathing as an underestimated risk, the KPNI lenses on pregnancy sleep, the typical pitfalls and three concrete, safe levers for the coming weeks. One thing upfront: this article does not replace a medical examination. With warning signs or uncertainty, your gynecologist or midwife is the right address.
Why sleep is disturbed differently by trimester
Sleep in pregnancy is not a uniform phenomenon. The triggers change with the hormonal and physical changes across the three trimesters. Those who know the cause can act more specifically instead of blindly fighting tiredness.
1st trimester: tired and yet awake
The strong rise in progesterone makes you tired (sedating effect), hence the great need for sleep during the day. At night, nausea, frequent urination due to increased kidney perfusion and breast tenderness disturb sleep. The need for sleep is high, the sleep quality often low nonetheless.
2nd trimester: the calmer phase
For many the most pleasant time. The nausea eases, the belly is not yet too big, the urge to urinate often less. But Mindell 2015 showed that nighttime awakening remains widespread throughout pregnancy. A good phase to consolidate sleep habits.
3rd trimester: the body as a disruptor
Belly size, heartburn, leg cramps, fetal movements, frequent nighttime urination and shortness of breath when lying on the back. In this phase the frequency of restless legs and insomnia also rises markedly.
Throughout: frequent awakening
Mindell 2015 found in the survey of 2427 pregnant women: 76 percent poor sleep quality, 57 percent insomnia symptoms, 24 percent restless legs symptoms, 19 percent signs of sleep-disordered breathing. Frequent nighttime awakening was practically universal.
Sleep patterns and sleep disturbances across pregnancy
Cross-sectional study Jodi Mindell, Rae Ann Cook and Janeta Nikolovski published in 2015 in Sleep Medicine a survey of 2427 pregnant women across all months of pregnancy. Results: 76 percent reported poor sleep quality, 38 percent too short night sleep, 49 percent pronounced daytime sleepiness. Insomnia symptoms were at 57 percent, signs of sleep-disordered breathing at 19 percent, restless legs symptoms at 24 percent. Frequent urination (83 percent) and the difficulty finding a comfortable position (79 percent) were the most frequently named disruptors. The authors recommend actively addressing sleep throughout pregnancy, because poor sleep quality can be associated with maternal and fetal outcomes.
Mindell JA, Cook RA, Nikolovski J. Sleep Med. 2015;16(4):483-8. doi:10.1016/j.sleep.2014.12.006 · PMID: 25666847
How common true insomnia is shown by a meta-analysis from Salari and colleagues in 2021 in BMC Pregnancy and Childbirth: in the third trimester the pooled prevalence of insomnia is well above that of the general population. This underlines that these are not isolated cases but a widespread phenomenon with a clear temporal clustering toward the end of pregnancy.
The sleeping position: what the evidence shows
Hardly any topic causes more uncertainty than the question "which side may I sleep on?". The most important message upfront, so that no fear arises: it is about the position when falling asleep in the last third of pregnancy, not about whether you briefly wake up on your back at night. If you wake up on your back, simply turn back onto your side. The absolute risk remains low.
Going-to-sleep position and the risk of late stillbirth
Meta-analysis Robin Cronin and colleagues evaluated in 2019 in EClinicalMedicine the individual participant data from five case-control studies, in total 851 late stillbirths and 2257 controls. Result: falling asleep in the supine position from 28 weeks of gestation was associated with an approximately 2.6-fold increased risk of late stillbirth, independent of other known risk factors. The association persisted even after accounting for fetal vulnerability. The authors emphasize that the going-to-sleep position is an easily modifiable factor and recommend lying on the side to fall asleep from the third trimester onward.
Cronin RS, Li M, Thompson JMD, et al. EClinicalMedicine. 2019;10:49-57. doi:10.1016/j.eclinm.2019.03.014 · PMID: 31193832
Supine position as a modifiable risk factor (New Zealand)
Case-control study Lesley McCowan and colleagues published in 2017 in PLoS One the New Zealand multicenter stillbirth case-control study. Here too, falling asleep in the supine position in late pregnancy was linked to an increased risk of late stillbirth. An international case-control study from O'Brien and colleagues in 2019 in Birth reached comparable results on nighttime sleep practices. The mechanism hypothesis: in the supine position the heavy uterus can compress the inferior vena cava and the aorta, which can reduce perfusion of the placenta and fetus.
McCowan LME, Thompson JMD, Cronin RS, et al. PLoS One. 2017;12(6):e0179396. doi:10.1371/journal.pone.0179396 · PMID: 28609468
This data is no reason for panic, but for a simple routine: from the third trimester, lie on your side to fall asleep, preferably left, a pillow behind your back or between your knees. If you wake up on your back at night, that is no drama, simply turn back onto your side. It is about the position when falling asleep, not about seamless monitoring of the night. A calm, doable habit beats every worry.
Restless legs and the role of iron
Restless legs, a distressing urge to move especially in the evening and at rest, are strikingly common in pregnancy. In many they disappear again after birth. The good news: restless legs are among the treatable sleep disorders, above all via iron status.
Pregnancy as a risk factor for restless legs
Cohort study Mauro Manconi and colleagues showed in 2004 in Sleep Medicine that pregnant women have an approximately two- to threefold increased risk of restless legs, with prevalences depending on the study in the range of about 11 to 27 percent. The symptoms cluster in the third trimester and improve rapidly after birth in most women. A review by Srivanitchapoom, Pandey and Hallett in 2014 in Parkinsonism and Related Disorders summarizes the mechanisms and names iron and folate metabolism as well as hormonal factors as central contributors.
Manconi M, Govoni V, De Vito A, et al. Sleep Med. 2004;5(3):305-8. · PMID: 15165540 | Srivanitchapoom P, Pandey S, Hallett M. Parkinsonism Relat Disord. 2014;20(7):716-22. · PMID: 24768121
Low iron and folate status and restless legs
Cohort study Kathryn Lee and colleagues investigated in 2001 in Journal of Women's Health and Gender-Based Medicine the association between iron and folate status and restless legs as well as sleep disturbance in pregnancy. Lower folate and iron markers were associated with the occurrence of restless legs. This fits the known mechanism that iron is a cofactor of dopamine synthesis in the brain and that an iron deficiency can impair dopaminergic function, which plays a central role in restless legs.
Lee KA, Zaffke ME, Baratte-Beebe K. J Womens Health Gend Based Med. 2001;10(4):335-41. · PMID: 11445024
In practice this means: with disturbing restless legs, iron status should be checked, especially ferritin and transferrin saturation. With a documented deficiency, medically supervised iron supplementation can help relieve the symptoms. Non-pharmacologically, daytime movement, calf stretching, alternating warm or cool compresses and avoiding caffeine in the evening may help. Magnesium is often tried, but the evidence for it is limited (see Spoke 4). Dopaminergic RLS medications are not the standard in pregnancy and belong in medical hands.
Iron is not taken uncontrolled and not high-dose on suspicion. Too much iron is not harmless. Supplementation is done only with a documented deficiency and after consulting a doctor, with monitoring of the course. This applies especially in pregnancy.
Safety of sleep aids: what is allowed and what is not
Here is the most important rule of the whole spoke: in pregnancy no sleep aid is taken without consulting a doctor, not even a herbal one and not an over-the-counter one. Herbal does not equal harmless. The following overview does not replace medical advice, it only provides a rough orientation.
First choice: non-pharmacological
Sleep hygiene, sleeping position, treating the cause (iron for RLS, heartburn management) and above all cognitive behavioral therapy for insomnia (CBT-I). These methods have the best benefit-risk ratio, because they do not expose the unborn child to a medication risk.
Only after a medical decision
Some agents such as doxylamine are used by doctors in certain situations. That is an individual weighing by the doctor, not a self-medication tip. Benefit and risk are weighed case by case.
Cautious to avoided
Benzodiazepines and Z-drugs (zolpidem, zopiclone) are used cautiously to not at all in pregnancy. The safety data are limited and there can be risks for the newborn. Never on your own.
Not sufficiently studied
Melatonin, valerian, passionflower, hops and various sleep and nerve teas have not been sufficiently studied in pregnancy. "Herbal" does not mean "safe". Do not use without consulting a doctor.
Over-the-counter and herbal sleep aids too are not automatically harmless in pregnancy. Teas and dietary supplements can contain active ingredients that are not studied or not recommended in pregnancy. Do not make an independent decision about sleep aids. Before any intake, speak with your gynecologist, your midwife or a pharmacy, ideally with a look into a specialized medicines-in-pregnancy database.
CBT-I: the safe standard against insomnia
When the insomnia persists over weeks and burdens the day, cognitive behavioral therapy for insomnia (CBT-I) is the method of choice. It carries no medication risk and is for exactly that reason particularly attractive in pregnancy.
CBT-I for insomnia in pregnancy
RCT Rachel Manber and colleagues studied in 2019 in Obstetrics and Gynecology cognitive behavioral therapy for prenatal insomnia in a randomized controlled trial. The CBT-I group more often achieved remission of the insomnia than the control group (remission defined via a low Insomnia Severity Index). The study supports CBT-I as an effective, non-pharmacological approach that has a favorable benefit-risk profile in this phase of life.
Manber R, Bei B, Simpson N, et al. Obstet Gynecol. 2019;133(5):911-919. doi:10.1097/AOG.0000000000003216 · PMID: 30969203
CBT-I consists of several components: stimulus control (using the bed only for sleep and not for ruminating), a deliberately milder form of sleep restriction during pregnancy, the reduction of sleep-related worries and solid sleep hygiene. In pregnancy, the classic, strict sleep restriction is applied more cautiously, because sufficient recovery remains important. CBT-I can be delivered in person, via specialized sleep counseling or in digital form. The topic is closely linked to sleep hygiene, which is described in detail in the pillar.
Snoring and sleep-disordered breathing: underestimated
A topic often overlooked in pregnancy is sleep-disordered breathing. Due to weight gain, hormonal mucosal swelling and the higher diaphragm position, snoring increases, and in some women breathing pauses occur during sleep. This is not only a question of comfort.
Sleep-disordered breathing and pregnancy complications
Cohort study Francesca Facco and colleagues found in 2017 in Obstetrics and Gynecology, in a large cohort of first-time mothers, that objectively measured sleep-disordered breathing was associated with an increased risk of gestational diabetes and of hypertensive disorders of pregnancy. The connections are associations, so no proof of a direct cause. But they make clear that pronounced snoring with breathing pauses in pregnancy should receive medical attention and must not be dismissed as a mere nuisance.
Facco FL, Parker CB, Reddy UM, et al. Obstet Gynecol. 2017;129(1):31-41. doi:10.1097/AOG.0000000000001805 · PMID: 27926645
When you should raise this: with loud, newly appeared snoring, with breathing pauses observed by the partner, with pronounced daytime sleepiness, morning headaches or poorly controlled blood pressure. Sleep-disordered breathing is treatable, and the treatment can benefit both sleep and the pregnancy equally.
The 4 KPNI lenses on pregnancy sleep
Hormonal system
Progesterone makes you tired (sedating effect) and drives the early need for sleep. Estrogen and progesterone change mucous membranes and airways. The nighttime course of melatonin and the internal clock shift. The hormonal change is the main driver of altered sleep, expressed differently depending on the trimester.
Nervous system
The urge to move in restless legs is closely linked to dopaminergic function, for which iron is a cofactor. Worries, rumination and the tension around birth activate the sympathetic nervous system and make falling asleep harder. CBT-I targets exactly this, the overaroused, ruminating nervous system.
Metabolism
Iron and folate status influence restless legs and sleep quality. Sleep-disordered breathing is associated with disturbed glucose regulation and gestational diabetes (Facco 2017). Heartburn from the slowed gastrointestinal transit disturbs sleep additionally. Metabolism and sleep are closely linked in this phase.
Structure and mechanics
The growing uterus presses on the bladder, diaphragm and large vessels. From this follow urge to urinate, shortness of breath when lying on the back and the importance of the side position (Cronin 2019). Leg cramps and back pain are mechanically caused. Here, positioning, pillows and position habits help the most.
What does not work: typical pitfalls
"It is only herbal" is not a safety argument in pregnancy. Valerian, passionflower, hops, melatonin and various teas have not been sufficiently studied in pregnancy. Some ingredients are explicitly not recommended in this phase. Herbal remedies should be discussed with a doctor, midwife or pharmacy before intake, not tried on your own.
The data from Cronin 2019 concern the going-to-sleep position in the last third, not every brief phase on the back. Anyone who deduces from the study that they must anxiously control their position all night long harms their own sleep more than it helps. A simple falling-asleep habit on the side is the right consequence, not constant fear.
Iron helps with restless legs only when a deficiency is actually present. A blanket, high-dose iron intake on suspicion is not harmless and can harm the digestive system and well-being. First measure (ferritin, transferrin saturation), then supplement specifically and with medical supervision.
A single bad night does not harm the unborn child. The baby is supplied through the placenta. The pressure to sleep perfectly creates stress and worsens sleep additionally. What matters is the trend and the treatable disorders, not the single restless night.
Safety first, comfort then. And no single night decides anything.
Fall asleep on your side, clarify iron with a documented deficiency, no sleep aid on your own, get checked for snoring with breathing pauses, and with persistent insomnia CBT-I instead of a pill. That is the calm, safe path through the nights.
Three concrete, safe levers for the coming weeks
Make the side position a falling-asleep habit
From the third trimester, consistently fall asleep on your side, preferably left, with a pillow behind your back and one between your knees. If you wake up on your back, simply turn back onto your side, without panic. Cronin 2019 supports the side position as an easily modifiable factor. It costs nothing and is immediately doable.
Have treatable causes clarified medically
With restless legs, have ferritin and transferrin saturation checked (iron with a documented deficiency, Lee 2001, Manconi 2004). With loud snoring with breathing pauses or strong daytime tiredness, raise sleep-disordered breathing (Facco 2017). These are the sleep disorders you can really tackle specifically.
With persistent insomnia, CBT-I instead of self-medication
When the insomnia persists over weeks and burdens the day, cognitive behavioral therapy for insomnia (CBT-I) is the safe first choice (Manber 2019), in person or digital. No sleep aid without consulting a doctor, not even a herbal one. Safety first.
What matters in the end
Poor sleep in pregnancy is normal, exhausting and in many respects not entirely avoidable. But three things can be done: make the position when falling asleep safe, tackle the treatable causes (iron, sleep-disordered breathing, insomnia) specifically, and strictly observe safety with sleep aids. Those who heed this get the best out of a phase in which the body rewrites many rules.
And the most important reassurance remains: a single sleepless night decides nothing. This article does not replace a medical examination. With warning signs such as headache with visual disturbances, sudden edema, upper abdominal pain, persistently low mood or pronounced breathing pauses during sleep, a medical evaluation is the right next step.
Frequently asked questions about sleep in pregnancy
Why do I sleep so badly in pregnancy?
Poor sleep in pregnancy is the rule, not the exception. Mindell 2015 in Sleep Medicine surveyed 2427 pregnant women and found: 76 percent reported poor sleep quality, 57 percent insomnia symptoms, 24 percent restless legs symptoms. The causes differ by trimester. First trimester: high progesterone makes you tired, while nausea, frequent urination and breast tenderness disturb sleep. Second trimester: often the calmest phase, many sleep better. Third trimester: belly size, heartburn, leg cramps, fetal movements, frequent urination and shortness of breath when lying on the back disturb sleep heavily. This is physiological and not a sign that something is wrong. Still, it is worth identifying the cause, because some triggers (restless legs, sleep-disordered breathing) are specifically treatable.
In which position should I sleep during pregnancy?
From the third trimester onward, the side position is recommended, preferably the left side. Cronin 2019 in EClinicalMedicine, in an individual participant data meta-analysis, evaluated the data of 851 stillbirths and 2257 controls and found that falling asleep in the supine position from 28 weeks of gestation was associated with an approximately 2.6-fold increased risk of late stillbirth, independent of other risk factors. McCowan 2017 in PLoS One found a comparable association in the New Zealand case-control study. Important for context: it is about the position when falling asleep, not about whether you briefly wake up on your back at night. If you wake up on your back, simply turn back onto your side. A pillow behind your back or between your knees can help maintain the side position. The absolute risk remains low, but the effect is an easily modifiable factor.
What helps against restless legs in pregnancy?
Restless legs are common in pregnancy. Manconi 2004 in Sleep Medicine found a two- to threefold increased prevalence compared with non-pregnant women, clustering in the third trimester and usually improving after birth. The most important treatable factor is iron status. Lee 2001 in Journal of Women's Health and Gender-Based Medicine showed an association between low folate and iron status and RLS in pregnancy. It therefore makes sense to: have ferritin and transferrin saturation measured; if a deficiency is documented, medically supervised iron supplementation can help. Non-pharmacologically, daytime movement, stretching, warm or cool calf compresses and avoiding caffeine in the evening may help. Magnesium is often tried, but the evidence for it is limited (see Spoke 4). Dopaminergic RLS medications are not standard in pregnancy and belong in medical hands. Important: never take high-dose iron uncontrolled, only with a documented deficiency and after consulting a doctor.
Which sleep aids are allowed in pregnancy?
The most important principle: in pregnancy no sleep aid is taken without consulting a doctor. Non-pharmacological methods are first choice, above all sleep hygiene and cognitive behavioral therapy for insomnia. Manber 2019 in Obstetrics and Gynecology showed in a randomized trial that CBT-I can be effective in pregnant women. Classic benzodiazepines and Z-drugs (zolpidem, zopiclone) are used cautiously to not at all in pregnancy, because safety data are limited and there can be risks for the newborn. Herbal remedies are not automatically safe: valerian, passionflower and some teas have not been sufficiently studied in pregnancy and should not be used without consultation. Melatonin too has not been sufficiently studied in pregnancy and is not routinely recommended. Doxylamine is used by doctors in some situations, but that too belongs to a medical decision. In short: no self-experimentation, always consult.
Is it bad if I sleep too little in pregnancy?
Occasional sleepless nights are normal in pregnancy and no cause for concern. The unborn child is supplied through the placenta and takes no direct harm from a restless night. What research does show: persistently poor sleep and certain sleep disorders are associated with pregnancy complications. Facco 2017 in Obstetrics and Gynecology found in a large cohort that objectively measured sleep-disordered breathing was associated with an increased risk of gestational diabetes and hypertensive disorders of pregnancy. These connections are associations, not proof of a direct cause. In practice this means: a single bad night is harmless, but persistent or pronounced sleep disorders should be medically evaluated, especially with loud snoring, breathing pauses or marked daytime sleepiness.
Why am I so tired in the first trimester and still wake up?
The first trimester is hormonally a roller coaster. The strong rise in progesterone makes you tired during the day (sedating effect), which is the reason for the pronounced need for sleep at the beginning. At the same time, typical early pregnancy symptoms disturb night sleep: nausea, increased urination due to increased kidney perfusion, breast tenderness and sometimes anxieties around the new situation. Mindell 2015 documented that frequent nighttime awakenings and daytime sleepiness are widespread throughout pregnancy. Strategies for the first trimester: allow short naps, wind down earlier in the evening, reduce fluid intake somewhat in the evening (but drink enough during the day), small meals if nauseated. If daytime tiredness is extreme or accompanied by dizziness and racing heart, it is worth checking iron and thyroid.
Does cognitive behavioral therapy help with sleep problems in pregnancy?
Yes, cognitive behavioral therapy for insomnia (CBT-I) is the non-pharmacological standard and particularly attractive in pregnancy because it carries no medication risk. Manber 2019 in Obstetrics and Gynecology studied CBT-I randomized in pregnant women with insomnia and found a higher remission rate than in the control group. CBT-I consists of several components: stimulus control (using the bed only for sleep), sleep restriction in an adapted, milder form during pregnancy, reducing sleep-related worries and sleep hygiene. In pregnancy, classic sleep restriction is applied more cautiously because sufficient recovery is important. CBT-I can also be delivered in digital form or via specialized sleep counseling. It is the method with the best benefit-risk ratio in this phase of life.
When should I see a doctor about sleep problems in pregnancy?
A medical evaluation makes sense with: loud snoring with observed breathing pauses or pronounced daytime sleepiness (suspicion of sleep-disordered breathing, see Facco 2017); with distressing restless legs that regularly rob sleep (restless legs, check iron status); with persistent insomnia over several weeks with clear daytime impairment; with low mood, lack of drive or anxieties (sleep disorder and perinatal depression are closely linked); with severe nighttime heartburn or shortness of breath; and always with warning signs such as headache with visual disturbances, sudden edema or upper abdominal pain (possible signs of hypertensive disorders of pregnancy). This article does not replace a medical examination. If unsure or with warning signs, please contact your gynecologist or midwife.
More from the cluster "Treating sleep disorders holistically"
- Pillar: Treating sleep disorders holistically
- Spoke 4: Magnesium and sleep
- Spoke 11: Restless Legs Syndrome
- Spoke 16: Sleep in Pregnancy (you are here)
Connections to other topics
The pillar article frames sleep hygiene, CBT-I and finding the cause. The foundation for every targeted step, also in pregnancy.
Mechanism, iron connection and treatment options in detail. In pregnancy, RLS is especially common and often well addressable via iron status.
What magnesium can do for sleep and for restless legs and what it cannot. The evidence is more limited than many think, and especially in pregnancy: only after consultation.
The non-pharmacological methods are first choice in pregnancy. What stimulus control and sleep hygiene look like in concrete terms is in the pillar.
Sources and further reading
- Mindell JA, Cook RA, Nikolovski J. Sleep patterns and sleep disturbances across pregnancy. Sleep Med. 2015;16(4):483-8. doi:10.1016/j.sleep.2014.12.006 · PMID: 25666847 [Cross-sectional study]
- Cronin RS, Li M, Thompson JMD, et al. An Individual Participant Data Meta-analysis of Maternal Going-to-Sleep Position, Interactions with Fetal Vulnerability, and the Risk of Late Stillbirth. EClinicalMedicine. 2019;10:49-57. doi:10.1016/j.eclinm.2019.03.014 · PMID: 31193832 [Meta-analysis]
- McCowan LME, Thompson JMD, Cronin RS, et al. Going to sleep in the supine position is a modifiable risk factor for late pregnancy stillbirth; Findings from the New Zealand multicentre stillbirth case-control study. PLoS One. 2017;12(6):e0179396. doi:10.1371/journal.pone.0179396 · PMID: 28609468 [Real-world]
- O'Brien LM, Warland J, Stacey T, et al. Maternal sleep practices and stillbirth: Findings from an international case-control study. Birth. 2019;46(2):344-354. doi:10.1111/birt.12416 · PMID: 30656734 [Real-world]
- Manconi M, Govoni V, De Vito A, et al. Restless legs syndrome and pregnancy. Sleep Med. 2004;5(3):305-8. · PMID: 15165540 [Review]
- Srivanitchapoom P, Pandey S, Hallett M. Restless legs syndrome and pregnancy: a review. Parkinsonism Relat Disord. 2014;20(7):716-22. · PMID: 24768121 [Mechanism review]
- Lee KA, Zaffke ME, Baratte-Beebe K. Restless legs syndrome and sleep disturbance during pregnancy: the role of folate and iron. J Womens Health Gend Based Med. 2001;10(4):335-41. · PMID: 11445024 [Real-world]
- Manber R, Bei B, Simpson N, et al. Cognitive Behavioral Therapy for Prenatal Insomnia: A Randomized Controlled Trial. Obstet Gynecol. 2019;133(5):911-919. doi:10.1097/AOG.0000000000003216 · PMID: 30969203 [RCT]
- Facco FL, Parker CB, Reddy UM, et al. Association Between Sleep-Disordered Breathing and Hypertensive Disorders of Pregnancy and Gestational Diabetes Mellitus. Obstet Gynecol. 2017;129(1):31-41. doi:10.1097/AOG.0000000000001805 · PMID: 27926645 [Real-world]
- Salari N, Darvishi N, Khaledi-Paveh B, et al. A systematic review and meta-analysis of prevalence of insomnia in the third trimester of pregnancy. BMC Pregnancy Childbirth. 2021;21(1):284. doi:10.1186/s12884-021-03755-z · PMID: 33836686 [Meta-analysis]
- Li M, Thompson JMD, Cronin RS, et al. The Collaborative IPD of Sleep and Stillbirth (Cribss): is maternal going-to-sleep position a risk factor for late stillbirth and does maternal sleep position interact with fetal vulnerability? A protocol. BMJ Open. 2018;8(4):e020323. doi:10.1136/bmjopen-2017-020323 · PMID: 29643161 [Protocol document]