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Associations between high temperatures in pregnancy and risk of preterm birth, low birth weight, and stillbirths: systematic review and meta-analysis.

ABSTRACT: OBJECTIVE:To assess whether exposure to high temperatures in pregnancy is associated with increased risk for preterm birth, low birth weight, and stillbirth. DESIGN:Systematic review and random effects meta-analysis. DATA SOURCES:Medline and Web of Science searched up to September 2018, updated in August 2019. ELIGIBILITY CRITERIA FOR SELECTING STUDIES:Clinical studies on associations between high environmental temperatures, and preterm birth, birth weight, and stillbirths. RESULTS:14?880 records and 175 full text articles were screened. 70 studies were included, set in 27 countries, seven of which were countries with low or middle income. In 40 of 47 studies, preterm births were more common at higher than lower temperatures. Exposures were classified as heatwaves, 1°C increments, and temperature threshold cutoff points. In random effects meta-analysis, odds of a preterm birth rose 1.05-fold (95% confidence interval 1.03 to 1.07) per 1°C increase in temperature and 1.16-fold (1.10 to 1.23) during heatwaves. Higher temperature was associated with reduced birth weight in 18 of 28 studies, with considerable statistical heterogeneity. Eight studies on stillbirths all showed associations between temperature and stillbirth, with stillbirths increasing 1.05-fold (1.01 to 1.08) per 1°C rise in temperature. Associations between temperature and outcomes were largest among women in lower socioeconomic groups and at age extremes. The multiple temperature metrics and lag analyses limited comparison between studies and settings. CONCLUSIONS:Although summary effect sizes are relatively small, heat exposures are common and the outcomes are important determinants of population health. Linkages between socioeconomic status and study outcomes suggest that risks might be largest in low and middle income countries. Temperature rises with global warming could have major implications for child health. SYSTEMATIC REVIEW REGISTRATION:PROSPERO CRD 42019140136 and CRD 42018118113.

SUBMITTER: Chersich MF

PROVIDER: S-EPMC7610201 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

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Associations between high temperatures in pregnancy and risk of preterm birth, low birth weight, and stillbirths: systematic review and meta-analysis.

Chersich Matthew Francis MF Pham Minh Duc MD Areal Ashtyn A Haghighi Marjan Mosalam MM Manyuchi Albert A Swift Callum P CP Wernecke Bianca B Robinson Matthew M Hetem Robyn R Boeckmann Melanie M Hajat Shakoor S

BMJ (Clinical research ed.) 20201104

<h4>Objective</h4>To assess whether exposure to high temperatures in pregnancy is associated with increased risk for preterm birth, low birth weight, and stillbirth.<h4>Design</h4>Systematic review and random effects meta-analysis.<h4>Data sources</h4>Medline and Web of Science searched up to September 2018, updated in August 2019.<h4>Eligibility criteria for selecting studies</h4>Clinical studies on associations between high environmental temperatures, and preterm birth, birth weight, and still ...[more]

PMID: 33148618

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Project description:ObjectiveTo determine the relation between overweight and obesity in mothers and preterm birth and low birth weight in singleton pregnancies in developed and developing countries.DesignSystematic review and meta-analyses.Data sourcesMedline and Embase from their inceptions, and reference lists of identified articles.Study selectionStudies including a reference group of women with normal body mass index that assessed the effect of overweight and obesity on two primary outcomes: preterm birth (before 37 weeks) and low birth weight (<2500 g).Data extractionTwo assessors independently reviewed titles, abstracts, and full articles, extracted data using a piloted data collection form, and assessed quality.Data synthesis84 studies (64 cohort and 20 case-control) were included, totalling 1 095 834 women. Although the overall risk of preterm birth was similar in overweight and obese women and women of normal weight, the risk of induced preterm birth was increased in overweight and obese women (relative risk 1.30, 95% confidence interval 1.23 to 1.37). Although overall the risk of having an infant of low birth weight was decreased in overweight and obese women (0.84, 0.75 to 0.95), the decrease was greater in developing countries than in developed countries (0.58, 0.47 to 0.71 v 0.90, 0.79 to 1.01). After accounting for publication bias, the apparent protective effect of overweight and obesity on low birth weight disappeared with the addition of imputed "missing" studies (0.95, 0.85 to 1.07), whereas the risk of preterm birth appeared significantly higher in overweight and obese women (1.24, 1.13 to 1.37).ConclusionsOverweight and obese women have increased risks of preterm birth and induced preterm birth and, after accounting for publication bias, appeared to have increased risks of preterm birth overall. The beneficial effects of maternal overweight and obesity on low birth weight were greater in developing countries and disappeared after accounting for publication bias.

Project description:BACKGROUND:Preterm birth is a disease of multifactorial etiologies that has environmental, social, and maternal health components. Individual studies have shown that exposure to arsenic contaminated drinking water, child marriage, and low maternal weight gain during pregnancy contribute to preterm birth. These factors are highly prevalent and often co-exist in Bangladesh, a country in South Asia with one of the world's highest prevalences of preterm birth. OBJECTIVE:To evaluate the individual and interactive effects of prenatal arsenic exposure, child marriage, and pregnancy weight gain on preterm birth in a prospective birth cohort in Bangladesh. METHODS:During 2008-2011, we recruited 1613 pregnant women aged ?18years at ?16weeks of gestation and followed them until 1-month post-partum. We measured total arsenic in drinking water (n=1184) and in maternal toenails (n=1115) collected at enrollment and ?1-month post-partum, respectively using inductively coupled plasma mass spectrometry. Child marriage (<18years old) was defined using self-report, and 2nd and 3rd trimester pregnancy weight gain was calculated using monthly records. Gestational age was determined at enrollment by ultrasound. RESULTS:In multivariate adjusted Poisson regression models, the risk ratios (RR) for preterm birth were 1.12 (95% CI: 1.07-1.18) for a unit change in natural log water arsenic exposure, 2.28 (95% CI: 1.76-2.95) for child marriage, and 0.64 (95% CI: 0.42-0.97) for a pound per week increase in maternal weight during the 2nd and 3rd trimesters. In stratified analysis by child marriage, pregnancy weight gain was inversely associated with preterm birth among women with a history of child marriage (RR=0.58; 95% CI: 0.37-0.92), but not among women with no history of child marriage (RR=86; 95% CI: 0.37-2.01). Mediation analysis revealed that both arsenic exposure and child marriage had small but significant associations with preterm birth via lowering pregnancy weight gain. Similar associations were observed when arsenic exposure was assessed using maternal toenail arsenic concentrations. CONCLUSIONS:Reducing arsenic exposure and ending child marriage could reduce the risk of preterm birth in Bangladesh. Furthermore, enhancing nutritional support to ensure adequate weight gain during pregnancy may provide additional benefits especially for women with a history of child marriage.

Project description:ImportanceSocial relationships are important determinants of well-being, health, and quality of life. There are conflicting findings regarding the association between preterm birth or low birth weight and experiences of social relationships in adulthood.ObjectiveTo systematically investigate the association between preterm birth or low birth weight and social outcomes in adulthood.Data sourcesPubMed, PsycINFO, Web of Science, and Embase were searched for peer-reviewed articles published through August 5, 2018.Study selectionProspective longitudinal and registry studies reporting on selected social outcomes in adults who were born preterm or with low birth weight (mean sample age ≥18 years) compared with control individuals born at term.Data extraction and synthesisThe meta-analysis followed Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The data were collected and extracted by 2 independent reviewers. Pooled analyses were based on odds ratios (ORs) with 95% confidence intervals and Hedges g, which were meta-analyzed using random-effects models.Main outcomes and measuresEver being in a romantic partnership, ever having experienced sexual intercourse, parenthood, quality of romantic relationship, and peer social support.ResultsTwenty-one studies were included of the 1829 articles screened. Summary data describing a maximum of 4 423 798 adult participants (179 724 preterm or low birth weight) were analyzed. Adults born preterm or with low birth weight were less likely to have ever experienced a romantic partnership (OR, 0.72; 95% CI, 0.64-0.81), to have had sexual intercourse (OR, 0.43; 95% CI, 0.31-0.61), or to have become parents (OR, 0.77; 95% CI, 0.65-0.91) than adults born full-term. A dose-response association according to degree of prematurity was found for romantic partnership and parenthood. Overall, effect sizes did not differ with age and sex. When adults born preterm or with low birth weight were in a romantic partnership or had friends, the quality of these relationships was not poorer compared with adults born full-term.Conclusions and relevanceThese findings suggest that adults born preterm or with low birth weight are less likely to experience a romantic partnership, sexual intercourse, or to become parents. However, preterm birth or low birth weight does not seem to impair the quality of relationships with partners and friends. Lack of sexual or partner relationships might increase the risk of decreased well-being and poorer physical and mental health.

Project description:Previous reviews (2005 to 2009) on preterm infants given probiotics or prebiotics with breast milk or mixed feeds focused on prevention of Necrotizing Enterocolitis, sepsis and diarrhea. This review assessed if probiotics, prebiotics led to improved growth and clinical outcomes in formula fed preterm infants.Cochrane methodology was followed using randomized controlled trials (RCTs) which compared preterm formula containing probiotic(s) or prebiotic(s) to conventional preterm formula in preterm infants. The mean difference (MD) and corresponding 95% confidence intervals (CI) were reported for continuous outcomes, risk ratio (RR) and corresponding 95% CI for dichotomous outcomes. Heterogeneity was assessed by visual inspection of forest plots and a chi² test. An I² test assessed inconsistencies across studies. I²> 50% represented substantial heterogeneity.Four probiotics studies (N=212), 4 prebiotics studies (N=126) were included. Probiotics: There were no significant differences in weight gain (MD 1.96, 95% CI: -2.64 to 6.56, 2 studies, n=34) or in maximal enteral feed (MD 35.20, 95% CI: -7.61 to 78.02, 2 studies, n=34), number of stools per day increased significantly in probiotic group (MD 1.60, 95% CI: 1.20 to 2.00, 1 study, n=20). Prebiotics: Galacto-oligosaccharide/Fructo-oligosaccharide (GOS/FOS) yielded no significant difference in weight gain (MD 0.04, 95% CI: -2.65 to 2.73, 2 studies, n=50), GOS/FOS yielded no significant differences in length gain (MD 0.01, 95% CI: -0.03 to 0.04, 2 studies, n=50). There were no significant differences in head growth (MD -0.01, 95% CI: -0.02 to 0.00, 2 studies, n=76) or age at full enteral feed (MD -0.79, 95% CI: -2.20 to 0.61, 2 studies, n=86). Stool frequency increased significantly in prebiotic group (MD 0.80, 95% CI: 0.48 to 1.1, 2 studies, n=86). GOS/FOS and FOS yielded higher bifidobacteria counts in prebiotics group (MD 2.10, 95% CI: 0.96 to 3.24, n=27) and (MD 0.48, 95% CI: 0.28 to 0.68, n=56).There is not enough evidence to state that supplementation with probiotics or prebiotics results in improved growth and clinical outcomes in exclusively formula fed preterm infants.

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Associations between high temperatures in pregnancy and risk of preterm birth, low birth weight, and stillbirths: systematic review and meta-analysis.

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Associations between high temperatures in pregnancy and risk of preterm birth, low birth weight, and stillbirths: systematic review and meta-analysis.

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