Clinical ReviewPolysomnographic features of pregnancy: A systematic review
Introduction
Pregnancy is a physiological condition of relatively short duration in a woman's life, but characterized by profound biological changes, which have a significant influence on sleep [1].
The typically increased secretion of several hormones across pregnancy considerably impacts on both the circadian and homeostatic components of sleep regulation, leading to modifications of sleep architecture [2]. In human studies, non-rapid eye movement sleep (NREM) has been shown to be enhanced by progesterone and prolactin [3,4], while rapid eye movement sleep (REM) is decreased by progesterone and increased by estrogens [5,6]. Oxytocin peaks during the night, promoting uterine contractions leading to sleep fragmentation [2]. Cortisol and growth hormone levels are also elevated, affecting sleep quality and inducing daytime sleepiness [2].
Besides hormones, other factors contribute to sleep disruption during pregnancy: gastroesophageal reflux, affecting up to 75% of pregnant women [7]; nocturnal micturition, due to an increase in overnight sodium excretion [8]; anatomical changes related to the growing uterus and increased body weight [9]. Moreover, iron and folate deficiency may play a role in the occurrence of sleep-related movement disorders in pregnant women [10,11].
Subjectively reported sleep disturbances are very common during pregnancy, with increasing rates from the first (13%), to the second (19%), and third (66%) trimester of gestation [12,13]. A recent meta-analysis showed that 46% of women experience poor sleep quality during pregnancy, with an average score of the Pittsburgh Sleep Quality Index (PSQI) of 6.4 (95% CI, 5.3–6.85) and with a worsening trend from the 2nd to the 3rd trimester by an average of 1.68 points (95% CI, 0.42–2.94) [14]. While at early gestational age women mainly attribute sleep problems to nausea/vomiting, urinary frequency, and backpain [15], in late gestation up to 69.9% of women report difficulty in maintaining sleep, 34.8% early morning awakenings, and 23.7% difficulty falling asleep [16], mainly due to fetal movements, heartburn, cramps or tingling in the legs, and shortness of breath [13,[17], [18], [19]]. By the end of pregnancy almost all women suffer from recurrent and long wake episodes during the night [17,20].
Self-reported sleep duration also declines across pregnancy [21]. Moreover, objectively assessed sleep duration and quality are related to age and ethnicity, with non-Hispanic black and Asian women having the shortest sleep duration, and younger pregnant women having the highest amount of wake after sleep onset (WASO), the lowest sleep efficiency (SE), and the latest sleep midpoint [22].
To date, the available literature on sleep during pregnancy is mostly based on subjective information from screening questionnaires or interviews [14,19]. However, in recent years, an increasing number of studies investigated sleep in pregnant women objectively, by using polysomnography (PSG) or actigraphy. Sleep parameters derived from actigraphy may significantly differ from those obtained by PSG recordings and should therefore be interpreted with caution [23]. Thus, PSG remains the gold standard for sleep depiction, being the only reliable tool to precisely describe sleep macro- and microstructure, correctly estimate respiratory and motor events, and permit an accurate identification of pregnancy-related sleep disorders.
We here present the first systematic review of polysomnographic studies conducted in pregnant women, with the aim to provide a detailed overview about the intrinsic, objective features of sleep in normal, healthy pregnancy, as well as in some typical pregnancy-related complications.
Section snippets
Methods
We performed a systematic review of the literature by searching for studies reporting objective sleep parameters obtained by PSG in pregnant women until February 1, 2019. The review process followed the PRISMA statement guidelines [24]. The completed PRISMA checklist can be found in the Supplementary material section (Table S1).
Literature search
A detailed flowchart of the results of the literature search process is presented in Fig. 1. Finally, 40 studies were considered for the qualitative analysis (systematic review). Twenty-four of them were cross-sectional studies (n = 24), ten prospective cohort studies (n = 10), five clinical trials (n = 5), and one case–control study (n = 1). Out of 40 studies, n = 27 included a control group, while n = 13 were not controlled. Regarding the country of origin, most studies were performed in the
Discussion
Changes in sleep structure during pregnancy, as objectively measured by PSG, mainly consist in a reduction of sleep duration (TST), due to an increase of WASO, and in a transition from N3 and REM sleep to more superficial NREM sleep stages (N1, N2) [28,29]. As a result, mean SE is diminished and sleep is perceived as non-restorative across gestation [30].
These findings become particularly evident in the third trimester and are confirmed both by studies comparing pregnant with age-matched
Conflicts of interest
The authors have no conflicts of interest to disclose.
Acknowledgements
This work is supported by a grant of the Swiss National Science Foundation (SNSF 320030_160250/1) and a grant of the Ministero della Salute, Italy (“Perinatal depression: chronobiology, sleep-related risk factor and light therapy”, project code: PE-2011-02348727). The authors would like to thank Dr. Giorgio Treglia, MD, for his expert advice regarding the methodology of systematic reviews and meta-analyses.
References∗ (81)
- et al.
Sleep in women across the life span
Chest
(2018) - et al.
Predictors of gastroesophageal reflux symptoms in pregnant women screened for sleep disordered breathing: a secondary analysis
Clin Res Hepatol Gastroenterol
(2013 Feb) - et al.
Relaxin and its role in pregnancy
Endocrinol Metab Clin N Am
(1995) Sleep disturbance in pregnancy. A subjective survey
Am J Obstet Gynecol
(1972)- et al.
Sleep quality during pregnancy: a meta-analysis
Sleep Med Rev
(2018) - et al.
Is insomnia in late pregnancy a risk factor for postpartum depression/depressive symptomatology?
Psychiatry Res
(2011) - et al.
Sleep disturbances during pregnancy
J Obstet Gynecol Neonatal Nurs
(2000) - et al.
Sleep patterns and sleep disturbances across pregnancy
Sleep Med
(2015) - et al.
Effects of pregnancy on mothers' sleep
Sleep Med
(2002) - et al.
Objective sleep in pregnant women: a comparison of actigraphy and polysomnography
Sleep Heal
(2018)
Upper-airway flow limitation and transcutaneous carbon dioxide during sleep in normal pregnancy
Sleep Med
Childbearing in women with and without a history of affective disorder. II. Electroencephalographic sleep
Compr Psychiatr
Parity and sleep patterns during and after pregnancy
Obstet Gynecol
Normal pregnancy, daytime sleeping, snoring and blood pressure
Sleep Med
Obstructive sleep apnea in pregnancy. Is it a new syndrome in obstetrics? Egypt
J Chest Dis Tuberc
Airflow limitations in pregnant women suspected of sleep-disordered breathing
Sleep Med
Sleep-related disordered breathing during pregnancy in obese women
Chest
Normal pregnancy and oxygenation during sleep
Eur J Obstet Gynecol Reprod Biol
Hemodynamic responses to obstructive respiratory events during sleep are augmented in women with preeclampsia
Am J Hypertens
Pre-eclampsia and nasal CPAP: Part 1. Early intervention with nasal CPAP in pregnant women with risk-factors for pre-eclampsia: preliminary findings
Sleep Med
Obstructive sleep apnea in pregnancy and fetal outcome
Int J Gynecol Obstet
Pregnancy, sleep disordered breathing and treatment with nasal continuous positive airway pressure
Sleep Med
Typical sleep positions in pregnant women
Early Hum Dev
Prevalence of restless legs syndrome during pregnancy: a systematic review and meta-analysis
Sleep Med Rev
Is a one-night stay in the lab really enough to conclude? First-night effect and night-to-night variability in polysomnographic recordings among different clinical population samples
Psychiatry Res
Sleep disorders in pregnancy
Obstet Med
Sleep and the sleep electroencephalogram across the menstrual cycle in young healthy women
J Clin Endocrinol Metab
Enhanced slow wave sleep in patients with prolactinoma
J Clin Endocrinol Metab
Effect of oestrogen on the sleep, mood, and anxiety of menopausal women
BMJ
Effects of estrogens on sleep and psychological state of hypogonadal women
JAMA
Studies of nocturia in normal pregnancy
J Obstet Gynaecol Br Commonw
Restless legs syndrome and sleep disturbance during pregnancy: the role of folate and iron
J Women's Health Gend Based Med
Restless legs syndrome and pregnancy
Neurology
Insomnia and sleep deficiency in pregnancy
Obstet Med
Identifying insomnia in early pregnancy: validation of the insomnia symptoms questionnaire (ISQ) in pregnant women
J Clin Sleep Med
A postal survey of maternal sleep in late pregnancy
BMC Pregnancy Childbirth
A longitudinal study of sleep duration in pregnancy and subsequent risk of gestational diabetes: findings from a prospective, multiracial cohort
Am J Obstet Gynecol
Sleep during pregnancy: the nuMoM2b pregnancy and sleep duration and continuity study
Sleep
Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement
Syst Rev
Are healthcare workers' intentions to vaccinate related to their knowledge, beliefs and attitudes? A systematic review
BMC Public Health
Cited by (39)
Sleep health predicted glucose metabolism among pregnant women: A prospective cohort study
2024, Diabetes Research and Clinical PracticeCould sleep quality in pregnant women be related to developmental defects of enamel in children?
2024, Medical HypothesesSleep and sleep disorders during pregnancy and postpartum: The Life-ON study
2024, Sleep MedicineSleep Deficiency in Pregnancy
2023, Sleep Medicine ClinicsFetal heart rate responses to maternal sleep-disordered breathing
2023, American Journal of Obstetrics and GynecologyCitation Excerpt :Pregnancy amplifies disordered sleep. In particular, sleep-disordered breathing, characterized by recurrent episodes of complete (apnea) or partial (hypopnea) airway obstruction and oxyhemoglobin desaturation, is implicated in a host of adverse outcomes, including gestational diabetes, preeclampsia, preterm delivery, and stillbirth.1–4 Maternal obesity, a significant risk factor for sleep-disordered breathing, also poses well-identified and overlapping threats, making it difficult to isolate independent contributions of either.5
- ∗
The most important references are denoted by an asterisk.