Dataset Information

Ambient Temperature and Markers of Fetal Growth: A Retrospective Observational Study of 29 Million U.S. Singleton Births.

ABSTRACT: BACKGROUND:Emerging studies suggest that ambient temperature during pregnancy may be associated with fetal growth, but the existing evidence is limited and inconsistent. OBJECTIVES:We aimed to evaluate the association of trimester-specific temperature with risk of being born small for gestational age (SGA) and birth weight-markers of fetal growth-among term births in the contiguous United States. METHODS:We included data on 29,597,735 live singleton births between 1989 and 2002 across 403 U.S. counties. We estimated daily county-level population-weighted mean temperature using a spatially refined gridded climate data set. We used logistic regression to estimate the association between trimester-specific temperature and risk of SGA and linear regression to evaluate the association between trimester-specific temperature and term birth weight z-score, adjusting for parity, maternal demographics, smoking or drinking during pregnancy, chronic hypertension, and year and month of conception. We then pooled results overall and by geographic regions and climate zones. RESULTS:High ambient temperatures ([Formula: see text] percentile) during the entire pregnancy were associated with higher risk of term SGA {odds ratio [OR] [Formula: see text] 1.041 [95% confidence interval (CI): 1.029, 1.054]} and lower term birth weight [standardized to [Formula: see text] (95% CI: [Formula: see text], [Formula: see text]) reduction in birth weight for infants born at 40 weeks of gestation]. Low temperatures ([Formula: see text] percentile) during the entire pregnancy were not associated with SGA [OR [Formula: see text] 1.003 (95% CI: 0.991, 1.015)] but were associated with a small decrement in term birth weight [standardized to [Formula: see text] (95% CI: [Formula: see text], [Formula: see text])]. Risks of term SGA and birth weight were more strongly associated with temperature averaged across the second and third trimesters, in areas the Northeast, and in areas with cold or very cold climates. CONCLUSIONS:Above-average temperatures during pregnancy were associated with lower fetal growth. Our findings provide evidence that temperature may be a novel risk factor for reduced fetal growth. https://doi.org/10.1289/EHP4648.

SUBMITTER: Sun S

PROVIDER: S-EPMC6792370 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Ambient Temperature and Markers of Fetal Growth: A Retrospective Observational Study of 29 Million U.S. Singleton Births.

Sun Shengzhi S Spangler Keith R KR Weinberger Kate R KR Yanosky Jeff D JD Braun Joseph M JM Wellenius Gregory A GA

Environmental health perspectives 20190604 6

<h4>Background</h4>Emerging studies suggest that ambient temperature during pregnancy may be associated with fetal growth, but the existing evidence is limited and inconsistent.<h4>Objectives</h4>We aimed to evaluate the association of trimester-specific temperature with risk of being born small for gestational age (SGA) and birth weight-markers of fetal growth-among term births in the contiguous United States.<h4>Methods</h4>We included data on 29,597,735 live singleton births between 1989 and ...[more]

PMID: 31162981

Similar Datasets

Project description:BackgroundExtreme temperature is associated with adverse birth outcomes but it is unclear whether it increases early delivery risk.ObjectivesWe aimed to determine the association between ambient temperature and early delivery.MethodsMedical records from 223,375 singleton deliveries from 12 U.S. sites were linked to local ambient temperature. Exposure to hot (> 90th percentile) or cold (< 10th percentile) using site-specific and window-specific temperature distributions were defined for 3-months preconception, 7-week periods during the first two trimesters, 1 week preceding delivery, and whole pregnancy. Poisson regression with generalized estimating equations calculated the relative risk (RR) and 95% confidence interval for early deliveries associated with hot/cold exposures, adjusting for conception month, humidity, site, sex, maternal demographics, parity, insurance, prepregnancy body mass index, pregnancy complications, and smoking or drinking during pregnancy. Acute temperature associations were estimated separately for warm (May-September) and cold season (October-April) in a case-crossover analysis using conditional logistic regression.ResultsCompared with mild temperature (10-90th percentile), exposure to hot or cold during weeks 1-7 increased risk for early preterm (< 34 weeks) [RRhot: 1.11 (95% CI: 1.01, 1.21); RRcold: 1.20 (95% CI: 1.11, 1.30)], late preterm (34-36 weeks) [RRcold: 1.09 (95% CI: 1.04, 1.15)], and early term (37-38 weeks) [RRhot: 1.04 (95% CI: 1.02, 1.07); RRcold: 1.03 (95% CI: 1.00, 1.05)] delivery. Findings were similar for hot exposures during weeks 15-21. Examining deliveries at each week from 23 through 38, whole-pregnancy hot exposures increased delivery risk by 6-21% at weeks 34 and 36-38. In the case-crossover analysis, a 5°F increase during the week preceding delivery was associated with 12-16% higher and 4-5% lower early delivery risk during warm and cold season, respectively.ConclusionsBoth acute and chronic ambient temperature extremes may affect early delivery risk. Citation: Ha S, Liu D, Zhu Y, Kim SS, Sherman S, Mendola P. 2017. Ambient temperature and early delivery of singleton pregnancies. Environ Health Perspect 125:453-459;?http://dx.doi.org/10.1289/EHP97.

Project description:BackgroundPreterm birth rates have increased significantly worldwide over the past decade. Few epidemiological studies on the incidence of preterm birth and temporal trends are available in China. This study used national monitoring data from China's National Maternal Near Miss Surveillance System (NMNMSS) to estimate the rate of preterm birth and trends between 2012 and 2018 in China and to assess risk factors associated with preterm birth.MethodsIn this observational study, data were sourced from the NMNMSS between Jan 1, 2012, and Dec 31, 2018. Pregnancies with at least one livebirth, with the baby born at 28 weeks of gestation or more or 1000 g or more birthweight were included. We estimated the rates of overall preterm, very preterm (born between 28 and 31 weeks' gestation), moderate preterm (born between 32 and 33 weeks' gestation), and late preterm (born between 34 and 36 weeks' gestation) births in singleton and multiple pregnancies and assessed their trends over time. We used logistic regression analysis to examine the associations between preterm birth and sociodemographic characteristics and obstetric complications, considering the sampling strategy and clustering of births within hospitals. Interrupted time series analysis was used to assess the changes in preterm birth rates during the period of the universal two child policy intervention.FindingsFrom Jan 1, 2012, to Dec 31, 2018, 9 645 646 women gave birth to at least one live baby, of whom 665 244 (6·1%) were born preterm. In all pregnancies, the overall preterm birth rate increased from 5·9% in 2012 to 6·4% in 2018 (8·8% increase; annual rate of increase [ARI] 1·3 [95% CI 0·6 to 2·1]). Late preterm births (8·8%; ARI 1·5% [0·9 to 2·2]) and very preterm births (13·3%; ARI 1·8% [0·5 to 3·0]) significantly increased from 2012 to 2018, whereas moderate preterm births did not (3·8%; ARI 0·3% [95% CI -0·9 to 1·5]). In singleton pregnancies, the overall preterm birth rate showed a small but significant 6·4% increase (ARI 1·0% [0·4 to 1·7]) over the 7 year period. In multiple pregnancies, the overall preterm birth rate significantly increased from 46·8% in 2012 to 52·7% in 2018 (12·4% increase; ARI 1·9% [1·2 to 2·6]). Compared with women who gave birth in 2012, those who gave birth in 2018 were more likely to be older (aged ≥35 years; 7·4% in 2012 vs 15·9% in 2018), have multiples (1·6% vs 1·9%), have seven or more antenatal visits (50·2% vs 70·7%), and have antepartum complications and medical disease (17·9% vs 35·1%), but they were less likely to deliver via caesarean section (47·5% vs 45·0%). Compared with the baseline period (January, 2012 to June, 2016), a higher increase in preterm birth was observed after the universal two child policy came into effect in July, 2016 (β=0·034; p=0·03).InterpretationAn increase in preterm births was noted for both singleton and multiple pregnancies between 2012 and 2018 in China. China's strategic investment in maternal and neonatal health has been crucial for the prevention of preterm birth. Due to rapid changes in sociodemographic and obstetric factors related to preterm birth-particularly within the context of the universal two child policy-such as advanced maternal age at delivery, maternal complications, and multiple pregnancies, greater efforts to reduce the burden of preterm birth are urgently needed.FundingNational Key R&D Program of China, National Health Commission of the People's Republic of China, China Medical Board, WHO, and UNICEF.

Project description:BackgroundPreterm birth is the most common single cause of perinatal and infant mortality, affecting 15 million infants worldwide each year with global rates increasing. Understanding of risk factors remains poor, and preventive interventions have only limited benefit. Large differences exist in preterm birth rates across high income countries. We hypothesized that understanding the basis for these wide variations could lead to interventions that reduce preterm birth incidence in countries with high rates. We thus sought to assess the contributions of known risk factors for both spontaneous and provider-initiated preterm birth in selected high income countries, estimating also the potential impact of successful interventions due to advances in research, policy and public health, or clinical practice.MethodsWe analyzed individual patient-level data on 4.1 million singleton pregnancies from four countries with very high human development index (Czech Republic, New Zealand, Slovenia, Sweden) and one comparator U.S. state (California) to determine the specific contribution (adjusting for confounding effects) of 21 factors. Both individual and population-attributable preterm birth risks were determined, as were contributors to cross-country differences. We also assessed the ability to predict preterm birth given various sets of known risk factors.FindingsPrevious preterm birth and preeclampsia were the strongest individual risk factors of preterm birth in all datasets, with odds ratios of 4.6-6.0 and 2.8-5.7, respectively, for individual women having those characteristics. In contrast, on a population basis, nulliparity and male sex were the two risk factors with the highest impact on preterm birth rates, accounting for 25-50% and 11-16% of excess population attributable risk, respectively (p<0.001). The importance of nulliparity and male sex on population attributable risk was driven by high prevalence despite low odds ratios for individual women. More than 65% of the total aggregated risk of preterm birth within each country lacks a plausible biologic explanation, and 63% of difference between countries cannot be explained with known factors; thus, research is necessary to elucidate the underlying mechanisms of preterm birth and, hence, therapeutic intervention. Surprisingly, variation in prevalence of known risk factors accounted for less than 35% of the difference in preterm birth rates between countries. Known risk factors had an area under the curve of less than 0.7 in ROC analysis of preterm birth prediction within countries. These data suggest that other influences, as yet unidentified, are involved in preterm birth. Further research into biological mechanisms is warranted.ConclusionsWe have quantified the causes of variation in preterm birth rates among countries with very high human development index. The paucity of explicit and currently identified factors amenable to intervention illustrates the limited impact of changes possible through current clinical practice and policy interventions. Our research highlights the urgent need for research into underlying biological causes of preterm birth, which alone are likely to lead to innovative and efficacious interventions.

Project description:BackgroundExposure to heat during pregnancy has been associated with reduced fetal growth. Less is known about associations with cold and the potential for critical time windows of exposure.ObjectivesWe aimed to evaluate, in a national retrospective cohort, critical windows of susceptibility during pregnancy to extreme temperatures (low and high) and fetal growth, among 624,940 singleton term births in Israel during the period 2010-2014.MethodsTemperature exposures were estimated using a spatially refined gridded climate data set with a 1-h and 1-km2 resolution. Percentiles of temperature were categorized by climatic zone for the entire pregnancy and by trimesters and weeks. Generalized additive models with the distributed lag nonlinear model framework were used to estimate unadjusted and adjusted associations between percentiles and categories of temperature and fetal growth markers: term [births after 36 weeks of gestational age (GA)] mean birth weight and term low birth weight (tLBW, term infants with birth weight below 2,500g).ResultsAfter adjustment, extreme temperatures (percentiles) during the entire pregnancy were associated with a lower mean birth weight {≤10th vs. 41st-50th percentile: -56g [95% confidence interval (CI): -63g, -50g)]; >90th vs. 41st-50th percentile: -65g; 95% CI: -72g, -58g}. Similar inverse U-shaped patterns were observed for all trimesters, with stronger associations for heat than for cold and for exposures during the third trimester. For heat, results suggest critical windows between 3-9 and 19-34 GA-weeks, with the strongest association estimated at 3 GA-weeks (temperature >90th vs. 41st-50th percentiles: -3.8g; 95% CI: -7.1g, -0.4g). For cold, there was a consistent trend of null associations early in pregnancy and stronger inverse associations over time, with the strongest association at 36 GA-week (≤10th vs. 41st-50th percentiles: -2.9g; 95% CI: -6.5g, 0.7g). For tLBW, U-shape patterns were estimated for the entire pregnancy and third trimester exposures, as well as nonsignificant associations with heat for 29-36 GA-weeks. Generally, the patterns of associations with temperatures during the entire pregnancy were consistent when stratified by urbanicity and geocoding hierarchy, when estimated for daily minimum and maximum temperatures, when exposures were classified based on temperature distributions in 49 natural regions, and when estimated for all live births.DiscussionFindings from our study of term live births in Israel (2010-2014) suggest that exposure to extreme temperatures, especially heat, during specific time windows may result in reduced fetal growth. https://doi.org/10.1289/EHP8117.

Project description:BACKGROUND:In 2015, high rates of microcephaly were reported in Northeast Brazil following the first South American Zika virus (ZIKV) outbreak. Reported microcephaly rates in other Zika-affected areas were significantly lower, suggesting alternate causes or the involvement of arboviral cofactors in exacerbating microcephaly rates. METHODS AND FINDINGS:We merged data from multiple national reporting databases in Brazil to estimate exposure to 9 known or hypothesized causes of microcephaly for every pregnancy nationwide since the beginning of the ZIKV outbreak; this generated between 3.6 and 5.4 million cases (depending on analysis) over the time period 1 January 2015-23 May 2017. The association between ZIKV and microcephaly was statistically tested against models with alternative causes or with effect modifiers. We found no evidence for alternative non-ZIKV causes of the 2015-2017 microcephaly outbreak, nor that concurrent exposure to arbovirus infection or vaccination modified risk. We estimate an absolute risk of microcephaly of 40.8 (95% CI 34.2-49.3) per 10,000 births and a relative risk of 16.8 (95% CI 3.2-369.1) given ZIKV infection in the first or second trimester of pregnancy; however, because ZIKV infection rates were highly variable, most pregnant women in Brazil during the ZIKV outbreak will have been subject to lower risk levels. Statistically significant associations of ZIKV with other birth defects were also detected, but at lower relative risks than that of microcephaly (relative risk < 1.5). Our analysis was limited by missing data prior to the establishment of nationwide ZIKV surveillance, and its findings may be affected by unmeasured confounding causes of microcephaly not available in routinely collected surveillance data. CONCLUSIONS:This study strengthens the evidence that congenital ZIKV infection, particularly in the first 2 trimesters of pregnancy, is associated with microcephaly and less frequently with other birth defects. The finding of no alternative causes for geographic differences in microcephaly rate leads us to hypothesize that the Northeast region was disproportionately affected by this Zika outbreak, with 94% of an estimated 8.5 million total cases occurring in this region, suggesting a need for seroprevalence surveys to determine the underlying reason.

Project description:BackgroundThe available data regarding morbidity and mortality associated with multiple gestation births is conflicting and contradicting.ObjectiveTo compare morbidity, mortality, and length of stay (LOS) outcomes between multiple gestation (twin, triplet and higher-order) and singleton births.MethodsData from the national multicenter Kids' Inpatient Database of the Healthcare Cost and Utilization Project from the years 2000, 2003, 2006, 2009, 2012, and 2016 were analyzed using a complex survey design using Statistical Analysis System (SAS) 9.4 (SAS Institute, Cary NC). Neonates with ICD9 and ICD10 codes indicating singletons, twins or triplets, and higher-order multiples were included. Mortality was compared between these groups after excluding transfer outs to avoid duplicate inclusion. To analyze LOS, we included inborn neonates and excluded transfers; who died inpatient and any neonates who appear to have been discharged less than 33 weeks PMA. The LOS was compared by gestational age groups.ResultsA total of 22,853,125 neonates were analyzed for mortality after applying inclusion-exclusion criteria; 2.96% were twins, and 0.13% were triplets or more. A total of 22,690,082 neonates were analyzed for LOS. Mean GA, expressed as mean (SD), for singleton, twins and triplets, were 38.30 (2.21), 36.39 (4.21), and 32.72 (4.14), respectively. The adjusted odds for mortality were similar for twin births compared to singleton (aOR: 1.004, 95% CI:0.960-1.051, p = 0.8521). The adjusted odds of mortality for triplet or higher-order gestation births were higher (aOR: 1.33, 95% CI: 1.128-1.575, p = 0.0008) when compared to the singleton births. Median LOS (days) was significantly longer in multiple gestation compared to singleton births overall (singletons: 1.59 [1.13, 2.19] vs. twins 3.29 [2.17, 9.59] vs. triplets or higher-order multiples 19.15 [8.80, 36.38], p < .0001), and this difference remained significant within each GA category.ConclusionMultiple gestation births have higher mortality and longer LOS when compared to singleton births. This population data from multiple centers across the country could be useful in counseling parents when caring for multiple gestation pregnancies.

Project description:BackgroundAlthough studies have provided estimates of premature deaths attributable to either heat or cold in selected countries, none has so far offered a systematic assessment across the whole temperature range in populations exposed to different climates. We aimed to quantify the total mortality burden attributable to non-optimum ambient temperature, and the relative contributions from heat and cold and from moderate and extreme temperatures.MethodsWe collected data for 384 locations in Australia, Brazil, Canada, China, Italy, Japan, South Korea, Spain, Sweden, Taiwan, Thailand, UK, and USA. We fitted a standard time-series Poisson model for each location, controlling for trends and day of the week. We estimated temperature-mortality associations with a distributed lag non-linear model with 21 days of lag, and then pooled them in a multivariate metaregression that included country indicators and temperature average and range. We calculated attributable deaths for heat and cold, defined as temperatures above and below the optimum temperature, which corresponded to the point of minimum mortality, and for moderate and extreme temperatures, defined using cutoffs at the 2·5th and 97·5th temperature percentiles.FindingsWe analysed 74,225,200 deaths in various periods between 1985 and 2012. In total, 7·71% (95% empirical CI 7·43-7·91) of mortality was attributable to non-optimum temperature in the selected countries within the study period, with substantial differences between countries, ranging from 3·37% (3·06 to 3·63) in Thailand to 11·00% (9·29 to 12·47) in China. The temperature percentile of minimum mortality varied from roughly the 60th percentile in tropical areas to about the 80-90th percentile in temperate regions. More temperature-attributable deaths were caused by cold (7·29%, 7·02-7·49) than by heat (0·42%, 0·39-0·44). Extreme cold and hot temperatures were responsible for 0·86% (0·84-0·87) of total mortality.InterpretationMost of the temperature-related mortality burden was attributable to the contribution of cold. The effect of days of extreme temperature was substantially less than that attributable to milder but non-optimum weather. This evidence has important implications for the planning of public-health interventions to minimise the health consequences of adverse temperatures, and for predictions of future effect in climate-change scenarios.FundingUK Medical Research Council.

Dataset Information

Ambient Temperature and Markers of Fetal Growth: A Retrospective Observational Study of 29 Million U.S. Singleton Births.

Publications

Ambient Temperature and Markers of Fetal Growth: A Retrospective Observational Study of 29 Million U.S. Singleton Births.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets