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Table 2 Characteristics of studies included in the meta-analysis

From: Association between maternal sleep duration and quality, and the risk of preterm birth: a systematic review and meta-analysis of observational studies

First Author, (Ref), Year, CountryStudy DesignNo. of Case/Study sizeSource of patient recruitmentSleep assessmentPregnancy outcome categoriesExposure categories (period of exposure measurement)Risk Estimates
(95% CI)
Sleep Duration
Trivedi et al., [30] 2018, IndiaCohort study180/1977At household levelQuestionnairePreterm birthSleep hours per day
(> 8 h versus ≤ 8 h)
during antenatal period
0.93 (0.91–0.94)
Li et al., [31] 2017, ChinaCohort study32/688At three hospitalsQuestionnairePreterm birthAverage night’s sleep
(< 7 h versus ≥ 7 h)
12–16 weeks
24–28 weeks
32–36 weeks
0.58 (0.67–5.05)
1.56 (0.29–8.29)
4.67 (1.24–17.5)
Kajeepeta et al., [32] 2014, PeruvianCase-control study479/480At hospital levelQuestionnaire Hours of sleep per night
0–24 weeks
(≤6 h, ≥9 h versus 7–8 h)
 
Spontaneous Preterm Birth≤6 h
≥9 h
1.53 (1.08–2.17)
1.50 (1.04–2.16)
Spontaneous Very Preterm < 32 weeks≤6 h
≥9 h
1.25 (0.74–2.11)
1.48 (0.89–2.47)
Spontaneous Moderate Preterm 32–33 weeks≤6 h
≥9 h
1.82 (0.98–3.37)
1.98 (1.08–3.65)
Spontaneous Late Preterm 34- < 37 weeks≤6 h
≥9 h
1.64 (1.11–2.43)
1.10 (0.72–1.70)
Spontaneous Preterm Labor≤6 h
≥9 h
1.51 (1.00–2.29)
1.50 (0.99–2.27)
Preterm Premature Rupture of Membrane≤6 h
≥9 h
1.60 (1.06–2.40)
1.17 (0.74–1.83)
Guendelman et al., [12] 2013, USACohort study344/698A cohortQuestionnairePreterm birthTotal sleep duration
12–24 weeks
(< 7 h, > 8 h versus 7-8 h)
< 7 h
> 8 h
1.09 (0.80–1.48)
0.88 (0.57–1.48)
Okun et al., [33] 2012, USACohort study26/217Self-referral, physician referral, advertising, and screening in obstetrical ultrasound suitesQuestionnairePreterm birthTotal sleep duration
(< 7 h versus ≥ 7 h)
at 20 week
at 30 week
(> 9 h versus ≤ 9 h)
at 20 week
at 30 week
0.86 (0.29–2.59)
0.97 (0.31–3.02)
1.19 (0.38–3.75)
0.88 (0.20–3.91)
Reutrakul et al., [34] 2011, USACohort study56/116In all populationQuestionnairePreterm birthSleep duration per night
(< 7 h versus ≥ 7 h)
Second trimester
4.3 (1.1–16.7)
Micheli et al., [13] 2011, GreeceCohort study131/1091The Mother-child CohortQuestionnaire Sleep duration
24–36 weeks
(≤5 h, 6-7 h versus ≥ 8 h)
 
All preterm≤5 h
6-7 h
1.7 (1.1–2.8)
0.9 (0.6–1.4)
Medically Indicated Preterm≤5 h
6-7 h
2.4 (1.0–6.4)
1.2 (0.5–2.7)
Spontaneous Preterm≤5 h
6-7 h
1.6 (0.8–2.9)
0.9 (0.6–1.4)
Sleep Quality
Li et al., [31] 2017, ChinaCohort study32/688At three hospitalsQuestionnairePreterm birth(PSQI > 5 versus PSQI5)
12–16 weeks
24–28 weeks
32–36 weeks
2.04 (0.65–6.43)
5.35 (2.10–13.63)
3.01 (1.26–7.19)
Ota et al., [35] 2017, JapanCohort study23/122At hospitalQuestionnairePreterm birth(PSQI > 5 versus PSQI5)
at 16 week
3.4 (1.2–9.9)
Blair et al., [36] 2015, USACohort study12/138The Ohio State University Wexner Medical
Center and the surrounding community of Columbus
QuestionnairePreterm birth(PSQI > 5 versus PSQI5)
Mid-pregnancy
4.11 (1.04–16.25)
Reutrakul et al., [34] 2011, USACohort study74/116In all populationQuestionnairePreterm birth(PSQI > 5 versus PSQI5)
Second trimester
1.2 (1.0–1.3)
Okun et al., [14] 2011, USACohort study15/166A large university medical centerQuestionnairePreterm birth(PSQI > 5 versus PSQI5)
14–16 weeks
30–32 weeks
1.25 (1.04–1.50)
1.18 (0.98–1.42)
  1. The characteristics of the 10 studies (nine cohort studies and one case-controlled study) included for analysis are summarized in this table. The basic extracted information included the first author’s name; publication year; country of origin; study design; number of cases and populations; source of patient recruitment; sleep assessment; pregnancy outcome categories; exposure categories (period of exposure measurement); and risk estimates from the most fully adjusted model with associated 95% CI values
  2. Ref, Reference, CI Confidence interval, H Hours, NA Not available, PSQI Pittsburgh Sleep Quality Index