Association between temperature and maternal stress during pregnancy

Sex-specific effects of environmental temperature during gestation on fluctuating asymmetry in deciduous teeth

OBJECTIVES

External environmental heat exposure during gestation impacts the physiology of human development in utero, but evidence for these impacts has not yet been explored in dentition. We examined deciduous teeth for fluctuating asymmetry (FA), a measure of developmental instability, together with gestational environmental temperature data drawn from historical weather statistics.

MATERIALS AND METHODS

We measured dental casts from the longitudinal Burlington Growth Study, representing 172 participants (ages 3-6 years) with health records. FA was calculated from crown dimensions and intercuspal distances that develop during gestation. Multiple regression separated by sex (nfemale = 81) examined the effects of mean temperatures in each trimester, controlling for birth year.

RESULTS

In females, increased temperatures during the first trimester are significantly associated with an increase in FA (p = 0.03), specifically during the second and third prenatal months (p = 0.03). There is no relationship between temperature and FA for either sex in the second or third trimesters, when enamel is formed.

DISCUSSION

Dental instability may be sensitive to temperature in the first trimester in females during the scaffolding of crown shape and size in the earliest stages of tooth formation. Sexual dimorphism in growth investment strategies may explain the differences in results between males and females. Using enduring dental characteristics, these results advance our understanding of the effects of temperature on fetal physiology within a discrete period.

Association of Psychiatric Emergency Visits and Warm Ambient Temperature during Pregnancy: A Time-Stratified Case-Crossover Study

BACKGROUND

Acute exposure to high ambient temperature and heat waves during the warm season has been linked with psychiatric disorders. Emerging research has shown that pregnant people, due to physiological and psychological changes, may be more sensitive to extreme heat, and acute exposure has been linked to increased risk of pregnancy complications; however, few studies have examined psychiatric complications.

OBJECTIVE

Our objective was to examine the association between acute exposure to warm ambient temperatures and emergency department (ED) visits for mental disorders during pregnancy.

METHODS

A time-stratified case-crossover design with conditional logistic regression was performed on ∼ 206,000 psychiatric ED visits for pregnant patients in North Carolina, from May to September 2016 to 2019. Daily average ambient temperature was the main exposure and was linked to daily visits by maternal zip code of residence for prenatal mood and anxiety disorders (PMAD), severe mental illness (SMI), mental disorder of pregnancy (MDP), suicidal thoughts (SUIC), and any psychiatric disorder (Any). Effect modification by trimester, residential segregation, economic segregation, urbanicity, and availability of greenspace was also investigated.

RESULTS

Each 5 ° C increase in same-day exposure to warm ambient temperature on case days was associated with an increase in incidence rate ratio (IRR) for any psychiatric disorder [IRR = 1.07; 95% confidence interval (CI): 1.01, 1.14] including anxiety (IRR = 1.14; 95% CI: 1.00, 1.30), bipolar disorder (IRR = 1.28; 95% CI: 0.98, 1.67), and suicidal thoughts (IRR = 1.28; 95% CI: 1.00, 1.65) compared to control days. In general, the associations were strongest for warm season temperatures on the same day of exposure or for temperatures averaged over the 3 or 6 d preceding the ED visit. The greatest risk of an incident ED admission for PMAD (RR = 1.20; 95% CI: 1.04, 1.39), particularly for anxiety (RR = 1.30; 95% CI: 1.07, 1.59), and any psychiatric disorder (RR = 1.17; 95% CI: 1.07, 1.28) occurred following cumulative exposure to hot temperatures the week before admission. Higher psychiatric burden from temperature was observed in urban areas and on extreme heat days.

CONCLUSIONS

For this pregnant population in the southeastern United States, short-term exposure to high ambient temperatures during the warm season was associated with a greater risk of ED visits for an array of psychiatric disorders. Findings show that climate-related increases in ambient temperature may contribute to psychiatric morbidity in pregnant people. https://doi.org/10.1289/EHP13293.

Heat stress and adverse pregnancy outcome: Prospective cohort study

OBJECTIVE

To explore the relationship between occupational heat exposure, physiological heat strain indicators and adverse outcomes in pregnant women.

DESIGN

Prospective cohort.

SETTING

Workplaces in Tamil Nadu, India.

SAMPLE

A cohort of 800 pregnant women engaged in moderate to heavy physical work in 2017-2019 and 2021-2022.

METHODS

Participants were recruited at between 8 and 14 weeks of gestation. Occupational heat exposure and heat strain indicators were captured each trimester. 'Heat exposed' was defined as heat stress exceeding the threshold limit value (TLV) for safe manual work (with maximum wet-bulb globe temperatures of 27.5°C for a heavy workload and 28.0°C for a moderate workload). Physiological heat strain indicators (HSIs) such as core body temperature (CBT) and urine specific gravity (USG) were measured before and after each shift. Heat-related health symptoms were captured using the modified HOTHAPS questionnaire.

MAIN OUTCOME MEASURES

The main outcome measures included (1) a composite measure of any adverse pregnancy outcome (APO) during pregnancy (including miscarriage, preterm birth, low birthweight, stillbirth, intrauterine growth restriction and birth defects), (2) a composite measure of adverse outcomes at birth (3) and miscarriage.

RESULTS

Of the 800 participants, 47.3% had high occupational heat exposure. A rise in CBT was recorded in 17.4% of exposed workers, and 29.6% of workers experienced moderate dehydration (USG ≥ 1.020). Heat-exposed women had a doubled risk of miscarriage (adjusted odds ratio, aOR 2.4; 95% confidence interval, 95% CI 1.0-5.7). High occupational heat exposure was associated with an increased risk of any adverse pregnancy and foetal outcome (aOR 2.3; 95% CI 1.4-3.8) and adverse outcome at birth (aOR 2.0; 95% CI 1.2-3.3).

CONCLUSIONS

High occupational heat exposure is associated with HSIs and adverse pregnancy outcomes in India.

Extreme Heat and Pregnancy: A Content Analysis of Heat Health Risk Communication by US Public Health Agencies

OBJECTIVES

Exposure to extreme heat events increases the risk for negative birth outcomes, including preterm birth. This study sought to determine the presence and content of web-based heat health information for pregnant people provided by federal, state, and local government public health websites.

METHODS

This website content analysis consisted of 17 federal, 50 state, and 21 city websites, and noted which of 25 recognized pregnancy heat health data elements were included. Data for the analysis were collected from March 12, 2022, through March 16, 2022.

RESULTS

The search identified 17 federal websites, 38 state websites, and 19 city websites with heat health information. Within these, only seven websites listed pregnant people as a vulnerable or at-risk population, and only six websites provided information related to heat health specifically for pregnancy. Of the 25 themes recognized as important for pregnancy risk during extreme heat exposure, only 11 were represented within these 6 websites.

CONCLUSION

The presence of web-based pregnancy heat health information is infrequent and limited in content. Boosting web-based publication of extreme heat and pregnancy risks could mitigate negative maternal and child health outcomes.

Effect of maternal serum albumin level on birthweight and gestational age: an analysis of 39200 singleton newborns

Background

Serum albumin plays a pivotal role in regulating plasma oncotic pressure and modulating fluid distribution among various body compartments. Previous research examining the association between maternal serum albumin levels and fetal growth yielded limited and inconclusive findings. Therefore, the specific influence of serum albumin on fetal growth remains poorly understood and warrants further investigation.

Methods

A retrospective study involved 39200 women who had a singleton live birth at a tertiary-care academic medical center during the period from January 2017 to December 2020. Women were categorized into four groups according to the quartile of albumin concentration during early pregnancy: Q1 group, ≤41.0 g/L; Q2 group, 41.1-42.6 g/L; Q3 group, 42.7-44.3 g/L and Q4 group, >44.3 g/L. The main outcome measures were mid-term estimated fetal weight, birthweight and gestational age. Multivariate linear and logistic regression analysis were performed to detect the independent effect of maternal serum albumin level on fetal growth after adjusting for important confounding variables.

Results

In the crude analysis, a significant inverse correlation was found between early pregnancy maternal serum albumin levels and fetal growth status, including mid-term ultrasound measurements, mid-term estimated fetal weight, birthweight, and gestational age. After adjustment for a number of confounding factors, mid-term estimated fetal weight, birthweight, and birth height decreased significantly with increasing albumin levels. Compared to the Q2 group, the Q4 group had higher rates of preterm birth (aOR, 1.16; 95% CI, 1.01-1.34), small-for-gestational-age (aOR, 1.27; 95% CI, 1.11-1.45) and low birthweight (aOR, 1.41; 95% CI, 1.18-1.69), and lower rate of large-for-gestational-age (aOR, 0.85; 95% CI, 0.78-0.94). Moreover, to achieve the optimal neonatal outcome, women with higher early pregnancy albumin levels required a greater reduction in albumin levels in later pregnancy stages.

Conclusions

A higher maternal serum albumin level during early pregnancy was associated with poor fetal growth, with the detrimental effects becoming apparent as early as the mid-gestation period. These findings provided vital information for clinicians to predict fetal growth status and identify cases with a high risk of adverse neonatal outcomes early on.

Extreme heat, pregnancy and women's well-being in Burkina Faso: an ethnographical study

Climate change is an increasing threat to the health of populations in Africa, with a shift in seasonal temperatures towards more extreme heat exposures. In Burkina Faso, like other countries in the Sahel, many women have little protection against exposure to high temperatures, either outside or inside the home or place of work. This paper investigates how women perceive the impacts of heat on their physical and mental health, in addition to their social relationships and economic activities. Qualitative methods (in-depth interviews and focus group discussions) were conducted with women, community representatives and healthcare professionals in two regions in Burkina Faso. A thematic analysis was used to explore the realities of participants' experiences and contextual perspectives in relation to heat. Our research shows extreme temperatures have a multifaceted impact on pregnant women, mothers and newborns. Extreme heat affects women's functionality and well-being. Heat undermines a woman's ability to care for themselves and their child and interferes negatively with breast feeding. Heat negatively affects their ability to work and to maintain harmonious relationships with their partners and families. Cultural practices such as a taboo on taking the baby outside before the 40th day may exacerbate some of the negative consequences of heat. Most women do not recognise heat stress symptoms and lack awareness of heat risks to health. There is a need to develop public health messages to reduce the impacts of heat on health in Burkina Faso. Programmes and policies are needed to strengthen the ability of health professionals to communicate with women about best practices in heat risk management.

Educating Pregnant Women About the Dangers of Extreme Heat and Air Pollution

Climate change poses a serious threat to the health and well-being of pregnant women and their developing fetuses. Certain populations are at greater risk of adverse outcomes from air pollution, a contributing factor to climate change. In addition, heightened exposure to extreme heat, a consequence of climate change, exacerbates the existing health care inequities in the United States. Nurses, midwives, and other health care clinicians are uniquely positioned to reduce the harmful effects of climate change by educating pregnant women and their families and advocating for systems and policies that can decelerate climate change. The purpose of this article is to provide resources for clinicians to use in educating pregnant women about the risks of extreme heat and air pollution, their potential effects on pregnancy and neonatal outcomes, and strategies to help mitigate risk. We conclude with implications for practice, opportunities for advocacy, and areas for future research.

Pregnancy and newborn health - heat impacts and emerging solutions

Evidence is accumulating, both in the US and abroad, of the apparent serious health impacts of various environmental exposures tied to climate change. High ambient temperature, or heat, is a worsening global health risk. Heat risk is affected by many factors such as the magnitude, duration, and timing of exposure - such as specific, critical windows during pregnancy. This article focuses on the association of heat with both adverse pregnancy and newborn health outcomes. Regarding pregnancy, studies link heat and preterm birth, low birth weight and stillbirth. Multiple potential mechanisms support the biological plausibility of these associations. Emerging evidence suggests that heat, via epigenetics, may affect maternal health far beyond pregnancy. For newborn health impacts, heat is associated with increased hospitalization, neurologic and gastrointestinal dysfunction, and infant death. Research gaps include the need to study neonates separately from children and determining the mechanisms linking heat to adverse outcomes. We also highlight disparate adverse reproductive health outcomes for communities of color and low income tied to disproportionate exposures to environmental stressors like heat. Finally, we summarize educational and clinical tool resources for clinicians, information for patients, and opportunities for near-term action using the precautionary principle framework.

Acute air pollution and temperature exposure as independent and joint triggers of spontaneous preterm birth in New South Wales, Australia: a time-to-event analysis

Introduction

Exposure to high ambient temperatures and air pollution has been shown to increase the risk of spontaneous preterm birth (sPTB). Less clear are the effects of cold and the joint effects of air pollution and temperature.

Methods

Using a Cox proportional hazard regression model, we assessed the risk of independent and combined short-term exposure to ambient daily mean temperature and PM2.5 associated with sPTB in the last week before delivery on overall sPTB (weeks 23-36) and three subtypes: extremely sPTB, very sPTB, and moderate-to-late sPTB for a birth cohort of 1,318,570 births from Australia (Jan 2001-Dec 2019), while controlling for chronic exposure (i.e., throughout pregnancy except the last week before delivery) to PM2.5 and temperature. The temperature was modeled as a natural cubic spline, PM2.5 as a linear term, and the interaction effect was estimated using a multiplicative term. For short-term exposure to temperature hazard ratios reported are relative to the median temperature (18.1°C).

Results

Hazard ratios at low temperature [5th percentile(11.5°C)] were 0.95 (95% CI: 0.90, 1.00), 1.08 (95% CI: 0.84, 1.4), 0.87 (95% CI: 0.71, 1.06), and 1.00 (95% CI: 0.94, 1.06) and greater for high temperature [95th percentile (24.5°C)]: 1.22 (95% CI: 1.16, 1.28), 1.27 (95% CI: 1.03, 1.57), and 1.26 (95% CI: 1.05, 1.5) and 1.05 (1.00, 1.11), respectively, for overall, extremely, very, and moderate-to-late sPTBs. While chronic exposure to PM2.5 had adverse effects on sPTB, short-term exposure to PM2.5 appeared to have a negative association with all types of sPTB, with hazard ratios ranging from 0.86 (95th CI: 0.80, 0.94) to 0.98 (95th CI: 0.97, 1.00) per 5 μg/m3 increase in PM2.5.

Discussion

The risk of sPTB was found to increase following acute exposure to hot and cold ambient temperatures. Earlier sPTB subtypes seemed to be the most vulnerable. This study adds to the evidence that short-term exposure to ambient cold and heat and longer term gestational exposure to ambient PM2.5 are associated with an elevated risk of sPTB.

Association between low ambient temperature during pregnancy and adverse birth outcomes: A systematic review and meta-analysis

BACKGROUND

Extreme temperature events, including extreme cold, are becoming more frequent worldwide, which might be harmful to pregnant women and cause adverse birth outcomes. We aimed to investigate the association between exposure to low ambient temperature in pregnant women and adverse birth outcomes, such as preterm birth, low birth weight, and stillbirth, and to summarize the evidence herein.

METHODS

Relevant studies were searched in PubMed, Cochrane, and Embase electronic databases until November 2021. Studies involving low ambient temperature, preterm birth, birth weight, and stillbirth were included. The guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analyses were followed to conduct this study risk of bias and methods for data synthesis.

RESULTS

A total of 34 studies were included. First, pregnant women exposed to low ambient temperature had an increased risk of preterm birth (risk ratio [RR] 1.08; 95% confidence interval [CI] 1.04-1.13). Subgroup analyses revealed that exposure during late pregnancy was more likely to induce preterm birth. In addition, only pregnant women exposed to <1st percentile of the mean temperature suffered increased risk of preterm birth. Moreover, pregnant women living in medium or hot areas were more prone to have preterm births than those in cold areas when exposed to low ambient temperatures. Asians and Blacks were more susceptible to low ambient temperatures than Caucasians. Second, pregnant women exposed to low ambient temperature had an increased risk of low birth weight (RR 1.07; 95% CI 1.03-1.12). Third, pregnant women had an increased risk of stillbirth while exposed to low ambient temperature during the entire pregnancy (RR 4.63; 95% CI 3.99-5.38).

CONCLUSIONS

Exposure to low ambient temperature during pregnancy increases the risk of adverse birth outcomes. Pregnant women should avoid exposure to extremely low ambient temperature (<1st percentile of the mean temperature), especially in their late pregnancy. This study could provide clues for preventing adverse outcomes from meteorological factors.

REGISTRATION

No. CRD42021259776 at PROSPERO ( https://www.crd.york.ac.uk/PROSPERO/ ).

"Mothers get really exhausted!" The lived experience of pregnancy in extreme heat: Qualitative findings from Kilifi, Kenya

Heat exposure in pregnancy is associated with a range of adverse health and wellbeing outcomes, yet research on the lived experience of pregnancy in high temperatures is lacking. We conducted qualitative research in 2021 in two communities in rural Kilifi County, Kenya, a tropical savannah area currently experiencing severe drought. Pregnant and postpartum women, their male spouses and mothers-in-law, community health volunteers, and local health and environment stakeholders were interviewed or participated in focus group discussions. Pregnant women described symptoms that are classically regarded as heat exhaustion, including dizziness, fatigue, dehydration, insomnia, and irritability. They interpreted heat-related tachycardia as signalling hypertension and reported observing more miscarriages and preterm births in the heat. Pregnancy is conceptualised locally as a 'normal' state of being, and women continue to perform physically demanding household chores in the heat, even when pregnant. Women reported little support from family members to reduce their workload at this time, reflecting their relative lack of autonomy within the household, but also potentially the 'normalisation' of heat in these communities. Climate change risk reduction strategies for pregnant women in low-resource settings need to be cognisant of local household gender dynamics that constrain women's capacity to avoid heat exposures.

Short-term effects of tropospheric ozone and other environmental factors on emergency admissions due to pregnancy complications: A time-series analysis in the Madrid Region

Air pollution has been linked to adverse neonatal outcomes, mainly in the case of prolonged exposures. This study focuses on the short-term effects on maternal health. We conducted a retrospective ecological time-series study in the Madrid Region covering the period 2013-2018. The independent variables were mean daily concentrations of tropospheric ozone (O3), particulate matter (PM10/PM2.5) and nitrogen dioxide (NO2), as well as noise levels. The dependent variables were daily emergency hospital admissions due to complications in pregnancy, childbirth and the puerperium. Poisson generalised linear regression models were fitted to quantify the relative and attributable risks, controlling for trend, seasonality, the autoregressive nature of the series, and a number of meteorological factors. There were 318 069 emergency hospital admissions due to obstetric complications across the 2191 days of study. Of this total: 13 164 (95%CI: 9930-16 398) admissions were attributable to exposure to O3, the only pollutant to show a statistically significant (p < 0.05) association with admissions due to hypertensive disorders; and 10 575 (95%CI: 3573-17 566) admissions were attributable to daytime noise levels, while admissions due to hyperemesis gravidarum and vomiting were related to exposure to night noise. Other pollutants which also displayed statistically significant associations were: NO2 concentrations, with admissions due to vomiting and preterm labour; PM10 concentrations, with premature rupture of membranes: and PM2.5 concentrations, with total complications. Exposure to a range of air pollutants, and ozone in particular, is associated with a higher number of emergency hospital admissions due to gestational complications. Hence, surveillance of environmental effects on maternal health should be intensified, and plans and strategies to minimise these should be drawn up.

A Comprehensive Review on Hot Ambient Temperature and its Impacts on Adverse Pregnancy Outcomes

INTRODUCTION

High workplace/ambient temperatures have been associated with Adverse Pregnancy Outcomes (APO). Millions of women working in developing nations suffer due to the rising temperatures caused by climate change. There are few pieces of research linking occupational heat stress to APO, and fresh evidence is required.

METHODOLOGY

We used databases including PubMed, Google Scholar, and Science Direct to search for research on high ambient/workplace temperatures and their effects. Original articles, newsletters, and book chapters were examined. The literature we analysed was categorised as follows: Heat, strain, and physical activity harming both mother and fetus. After categorising the literature, it was examined to identify the major results.

RESULTS

We found a definite association between heat stress and APOs such as miscarriages, premature birth, stillbirth, low birthweight, and congenital abnormalities in 23 research articles. Our work provides important information for future research into the biological mechanisms that create APOs and various prevention measures.

CONCLUSION

Our data suggest that temperature has long-term and short-term effects on maternal and fetal health. Though small in number, this study stressed the need for bigger cohort studies in tropical developing countries to create evidence for coordinated policies to safeguard pregnant women.

The Impact of Extreme Heat Exposure on Pregnant People and Neonates: A State of the Science Review

The relationship between heat exposure and perinatal morbidity and mortality is of increasing concern as global temperatures rise and extreme heat events become more frequent and intense. Heat exposure can lead to a multitude of harmful outcomes for pregnant individuals and neonates, including hospitalization and death. This state of the science review explored the evidence on the associations between heat exposure and negative health outcomes during pregnancy and the neonatal period. Findings suggest that improving health care provider and patient awareness of heat-related risks and implementing specific interventions could mitigate adverse outcomes. Furthermore, public health and other policy interventions are needed to increase thermal comfort and reduce societal exposure to extreme heat and related risks. Early warning systems, medical alerts, provider and patient education, and increased access to health care and thermal comfort may improve pregnancy and early life health outcomes.

Increasing global temperatures threaten gains in maternal and newborn health in Africa: A review of impacts and an adaptation framework

Anatomical, physiologic, and socio-cultural changes during pregnancy and childbirth increase vulnerability of women and newborns to high ambient temperatures. Extreme heat can overwhelm thermoregulatory mechanisms in pregnant women, especially during labor, cause dehydration and endocrine dysfunction, and compromise placental function. Clinical sequelae include hypertensive disorders, gestational diabetes, preterm birth, and stillbirth. High ambient temperatures increase rates of infections, and affect health worker performance and healthcare seeking. Rising temperatures with climate change and limited resources heighten concerns. We propose an adaptation framework containing four prongs. First, behavioral changes such as reducing workloads during pregnancy and using low-cost water sprays. Second, health system interventions encompassing Early Warning Systems centered around existing community-based outreach; heat-health indicator tracking; water supplementation and monitoring for heat-related conditions during labor. Building modifications, passive and active cooling systems, and nature-based solutions can reduce temperatures in facilities. Lastly, structural interventions and climate financing are critical. The overall package of interventions, ideally selected following cost-effectiveness and thermal modeling trade-offs, needs to be co-designed and co-delivered with affected communities, and take advantage of existing maternal and child health platforms. Robust-applied research will set the stage for programs across Africa that target pregnant women. Adequate research and climate financing are now urgent.

Maternal affective and stress-related factors during pregnancy affect the occurrence of childhood allergic diseases: A Shanghai MCPC study

OBJECTIVE

To investigate the association between exposures to maternal affective and stress-related factors during pregnancy and allergies in children from birth to 2 years of age.

METHODS

We enrolled a total of 4178 children from the Shanghai Maternal-Child Pairs Cohort and measured maternal stress, anxiety, and depression during pregnancy by applying the Life Events Scale for Pregnant Women, Self-Rating Anxiety Scale, and the Center for Epidemiologic Studies-Depression Scale, respectively. Children's allergies were assessed by community physicians at 2, 6, 12, and 24 months, respectively; these included eczema, atopic dermatitis, food allergy, wheezing, asthma, and atopic rhinitis. We applied a latent class analysis (LCA) to these factors and analyzed the impacts of maternal affective and stress-related factors on childhood allergies by exploiting multivariate logistic regression.

RESULTS

Three distinct classes of children were revealed by LCA: healthy (79.8%), transient allergy (15.2%), and persistent allergy (4.9%). High maternal stress in both early and late pregnancy was associated with an increased risk of infant eczema at 2 months (aOR = 1.30, 95% CI = 1.01-1.67; aOR = 1.64, 95% CI = 1.14-2.36). Moreover, high maternal stress in late pregnancy was also associated with food allergy at 6 months, rhinitis at 2 years of age, and persistent allergy (aOR = 3.22, 95% CI = 1.27-8.12; aOR = 1.78, 95% CI = 1.01-3.15; and aOR = 1.93, 95% CI = 1.10-3.40).

CONCLUSIONS

The associations of maternal affective and stress-related factors during pregnancy with childhood allergies may vary by type and disease onset. We postulate that maternal stress in late pregnancy may exert a sustained negative effect on early childhood allergic diseases.

Maternal psychological distress associates with alterations in resting-state low-frequency fluctuations and distal functional connectivity of the neonate medial prefrontal cortex

Prenatal stress exposure (PSE) has been observed to exert a programming effect on the developing infant brain, possibly with long-lasting consequences on temperament, cognitive functions and the risk for developing psychiatric disorders. Several prior studies have revealed that PSE associates with alterations in neonate functional connectivity in the prefrontal regions and amygdala. In this study, we explored whether maternal psychological symptoms measured during the 24th gestational week had associations with neonate resting-state network metrics. Twenty-one neonates (nine female) underwent resting-state fMRI scanning (mean gestation-corrected age at scan 26.95 days) to assess fractional amplitude of low-frequency fluctuation (fALFF) and regional homogeneity (ReHo). The ReHo/fALFF maps were used in multiple regression analysis to investigate whether maternal self-reported anxiety and/or depressive symptoms associate with neonate functional brain features. Maternal psychological distress (composite score of depressive and anxiety symptoms) was positively associated with fALFF in the neonate medial prefrontal cortex (mPFC). Anxiety and depressive symptoms, assessed separately, exhibited similar but weaker associations. Post hoc seed-based connectivity analyses further showed that distal connectivity of mPFC covaried with PSE. No associations were found between neonate ReHo and PSE. These results offer preliminary evidence that PSE may affect functional features of the developing brain during gestation.

Physiological mechanisms of the impact of heat during pregnancy and the clinical implications: review of the evidence from an expert group meeting

Many populations experience high seasonal temperatures. Pregnant women are considered vulnerable to extreme heat because ambient heat exposure has been linked to pregnancy complications including preterm birth and low birthweight. The physiological mechanisms that underpin these associations are poorly understood. We reviewed the existing research evidence to clarify the mechanisms that lead to adverse pregnancy outcomes in order to inform public health actions. A multi-disciplinary expert group met to review the existing evidence base and formulate a consensus regarding the physiological mechanisms that mediate the effect of high ambient temperature on pregnancy. A literature search was conducted in advance of the meeting to identify existing hypotheses and develop a series of questions and themes for discussion. Numerous hypotheses have been generated based on animal models and limited observational studies. There is growing evidence that pregnant women are able to appropriately thermoregulate; however, when exposed to extreme heat, there are a number of processes that may occur which could harm the mother or fetus including a reduction in placental blood flow, dehydration, and an inflammatory response that may trigger preterm birth. There is a lack of substantial evidence regarding the processes that cause heat exposure to harm pregnant women. Research is urgently needed to identify what causes the adverse outcomes in pregnancy related to high ambient temperatures so that the impact of climate change on pregnant women can be mitigated.

Does air pollution modify temperature-related mortality? A systematic review and meta-analysis

INTRODUCTION

There is an increasing interest in understanding whether air pollutants modify the quantitative relationships between temperature and health outcomes. The results of available studies were, however, inconsistent. This study aims to sum up the current evidence and provide a comprehensive understanding of this topic.

METHODS

We conducted an electronic search in PubMed (MEDLINE), EMBASE, Web of Science Core Collection, and ProQuest Dissertations and Theses. The modified Navigation Guide was applied to evaluate the quality and strength of evidence. We calculated pooled temperature-related mortality at low and high pollutant levels respectively, using the random-effects model.

RESULTS

We identified 22 eligible studies, eleven of which were included in the meta-analysis. Significant effect modification was observed on heat effects for all-cause and non-accidental mortality by particulate matter with an aerodynamic diameter of <10 μm (PM₁₀) and ozone (O₃) (p < 0.05). The excess risks (ERs) for all-cause and non-accidental mortality were 5.4% (4.4%, 6.4%) and 6.3% (4.8%, 7.8%) at the low PM₁₀ level, 8.8% (7.5%, 10.1%) and 11.4% (8.7%, 14.2%) at the high PM₁₀ level, respectively. As for O₃, the ERs for all-cause and non-accidental mortality were 5.1% (3.9%, 6.3%) and 3.6% (0.1%, 7.2%) at the low O₃ level, 7.6% (6.3%, 9.0%) and 12.5% (4.7%, 20.9%) at the high O₃ level, respectively. Surprisingly, the heat effects on cardiovascular mortality were found to be lower at high carbon monoxide (CO) levels [ERs = 5.4% (3.9%, 6.9%)] than that at low levels [ERs = 9.4% (7.0%, 11.9%)]. The heterogeneity varied, but the results of sensitivity analyses were generally robust. Significant effect modification by air pollutants was not observed for heatwave or cold effects.

CONCLUSIONS

PM₁₀ and O₃ modify the heat-related all-cause and non-accidental mortality, indicating that policymakers should consider air pollutants when establishing heat-health warning systems. Future studies with comparable designs and settings are needed.

The Changing Climate and Pregnancy Health

Purpose of Review

Climate change is the biggest public health threat of the twenty-first century but its impact on the perinatal period has only recently received attention. This review summarizes recent literature regarding the impacts of climate change and related environmental disasters on pregnancy health and provides recommendations to inform future adaptation and mitigation efforts.

Recent Findings

Accumulating evidence suggests that the changing climate affects pregnancy health directly via discrete environmental disasters (i.e., wildfire, extreme heat, hurricane, flood, and drought), and indirectly through changes in the natural and social environment. Although studies vary greatly in design, analytic methods, and assessment strategies, they generally converge to suggest that climate-related disasters are associated with increased risk of gestational complication, pregnancy loss, restricted fetal growth, low birthweight, preterm birth, and selected delivery/newborn complications. Window(s) of exposure with the highest sensitivity are not clear, but both acute and chronic exposures appear important. Furthermore, socioeconomically disadvantaged populations may be more vulnerable.

Summary

Policy, clinical, and research strategies for adaptation and mitigation should be continued, strengthened, and expanded with cross-disciplinary efforts. Top priorities should include (a) reinforcing and expanding policies to further reduce emission, (b) increasing awareness and education resources for healthcare providers and the public, (c) facilitating access to quality population-based data in low-resource areas, and (d) research efforts to better understand mechanisms of effects, identify susceptible populations and windows of exposure, explore interactive impacts of multiple exposures, and develop novel methods to better quantify pregnancy health impacts.

Extreme Heat and Pregnancy Outcomes: A Scoping Review of the Epidemiological Evidence

Background: Extreme heat caused by climate change is a major public health concern, disproportionately affecting poor and racialized communities. Gestational heat exposure is a well-established teratogen in animal studies, with a growing body of literature suggesting human pregnancies are similarly at risk. Characterization of extreme heat as a pregnancy risk is problematic due to nonstandard definitions of heat waves, and variable study designs. To better focus future research in this area, we conducted a scoping review to assess the effects of extreme heat on pregnancy outcomes. Methods: A scoping review of epidemiological studies investigating gestational heat-exposure and published 2010 and 2020, was conducted with an emphasis on study design, gestational windows of sensitivity, adverse pregnancy outcomes and characterization of environmental temperatures. Results: A sample of 84 studies was identified, predominantly set in high-income countries. Preterm birth, birthweight, congenital anomalies and stillbirth were the most common pregnancy outcome variables. Studies reported race/ethnicity and/or socioeconomic variables, however these were not always emphasized in the analysis. Conclusion: Use of precise temperature data by most studies avoided pitfalls of imprecise, regional definitions of heat waves, however inconsistent study design, and exposure windows are a significant challenge to systematic evaluation of this literature. Despite the high risk of extreme heat events and limited mitigation strategies in the global south, there is a significant gap in the epidemiological literature from these regions. Greater consistency in study design and exposure windows would enhance the rigor of this field.

Effect of Elevated Ambient Temperature on Maternal, Foetal, and Neonatal Outcomes: A Scoping Review

This scoping review provides an overview of the published literature, identifies research gaps, and summarises the current evidence of the association between elevated ambient temperature exposure during pregnancy and adverse maternal, foetal, and neonatal outcomes. Following the PRISMA extension for scoping reviews reporting guidelines, a systematic search was conducted on CINAHL, PubMed, and Embase and included original articles published in the English language from 2015 to 2020 with no geographical limitations. A total of seventy-five studies were included, conducted across twenty-four countries, with a majority in the USA (n = 23) and China (n = 13). Study designs, temperature metrics, and exposure windows varied considerably across studies. Of the eighteen heat-associated adverse maternal, foetal, and neonatal outcomes identified, pre-term birth was the most common outcome (n = 30), followed by low birth weight (n = 11), stillbirth (n = 9), and gestational diabetes mellitus (n = 8). Overall, papers reported an increased risk with elevated temperature exposures. Less attention has been paid to relationships between heat and the diverse range of other adverse outcomes such as congenital anomalies and neonatal mortality. Further research on these less-reported outcomes is needed to improve understanding and the effect size of these relationships with elevated temperatures, which we know will be exacerbated by climate change.

Effects of prenatal exposures to air sulfur dioxide/nitrogen dioxide on toddler neurodevelopment and effect modification by ambient temperature

Emerging evidence suggests that prenatal exposure to ambient SO2 or NO2 induces fetal brain-damage. However, effects of prenatal exposure to SO2 or NO2 on toddler neurodevelopment and the effect-modification by ambient temperature remain unclear. Therefore, a prospective birth-cohort study was conducted from 2010 to 2012 in Shanghai, and 225 mother-child pairs were followed-up from mid-to-late pregnancy until 24-36 months postpartum. During the whole pregnancy, daily SO2/NO2 and temperature levels were obtained for each woman. Gesell-Development-Schedule was used to assess toddler neurodevelopment in the domains of gross-motor, fine-motor, adaptive-behavior, language and social-behavior. Distributed-lag-nonlinear-models simultaneously accounting for exposure-response and lag-response associations were applied to assess the impacts of prenatal SO2/NO2 exposure on neurodevelopment. Each 10-μg/m3 increase in weekly average SO2 concentrations had adverse associations with gross-motor in gestational-weeks 1-6, with adaptive-behavior in weeks 26-30, and with language in weeks 30-36 (developmental-quotient changes: - 1.17% to - 0.12%, P-values < 0.05). Each 10-μg/m3 increase in weekly average NO2 concentrations had adverse associations with gross-motor in gestational-weeks 33-36, with fine-motor in weeks 26-36 and with social-behavior in weeks 31-36 (developmental-quotient changes: - 0.91% to - 0.20%, P-values < 0.05). The cumulative effects for the whole pregnancy showed that each 10-μg/m3 increase in SO2 induced significant deficits in gross-motor and adaptive-behavior (developmental-quotient changes: - 4.71% and - 4.06%, respectively, P < 0.05). We found prenatal cumulative SO2 exposure induced more deficits in low temperature in language and adaptive-behavior than in high/moderate temperature. Thus, prenatal ambient SO2/NO2 exposure in specific time-windows (1st and 3rd trimesters for SO2; 3rd trimester for NO2) could impair toddler neurodevelopment and low temperature may aggravate the SO2-induced neurotoxicity.

Sex-specific associations between maternal pregnancy-specific anxiety and newborn amygdalar volumes - preliminary findings from the FinnBrain Birth Cohort Study

Previous literature links maternal pregnancy-specific anxiety (PSA) with later difficulties in child emotional and social cognition as well as memory, functions closely related to the amygdala and the hippocampus. Some evidence also suggests that PSA affects child amygdalar volumes in a sex-dependent way. However, no studies investigating the associations between PSA and newborn amygdalar and hippocampal volumes have been reported. We investigated the associations between PSA and newborn amygdalar and hippocampal volumes and whether associations are sex-specific in 122 healthy newborns (68 males/54 females) scanned at 2-5 weeks postpartum. PSA was measured at gestational week 24 with the Pregnancy-Related Anxiety Questionnaire Revised 2 (PRAQ-R2). The associations were analyzed with linear regression controlling for confounding variables. PSA was associated positively with left amygdalar volume in girls, but no significant main effect was found in the whole group or in boys. No significant main or sex-specific effect was found for hippocampal volumes. Although this was an exploratory study, the findings suggest a sexually dimorphic association of mid-pregnancy PSA with newborn amygdalar volumes.

Influence of ambient temperature and diurnal temperature variation on the premature rupture of membranes in East China: A distributed lag nonlinear time series analysis

BACKGROUND

Extreme ambient temperature has an adverse effect on pregnancy outcomes, but the conclusions have been inconsistent. The influence of ambient temperature and diurnal temperature variation on the premature rupture of membranes (PROM) needs further study.

METHODS AND FINDINGS

The daily data of PROMs, daily meteorological and air pollutant were obtained. After controlling for potential confounding factors, the quasi-Poisson generalized additive model (GAM) combined with the distributed lag nonlinear model (DLNM) was used to analyze the association between temperature or diurnal temperature variation and PROM, including preterm premature rupture of membranes (PPROM) and term premature rupture of membranes (term PROM). Compared with the median temperature(18.7 °C), the mean temperature of 5-7 days lagging beyond 31.5 °C and below -1.5 °C was positively correlated with PROM; the mean temperature had more sensitive effect on the term PROM. Exposure to extremely high temperatures (97.5th percentile, 32 °C) had a 6-day lagging relative risk (RR) (95% CI: 1.005-1.160) of 1.08 for PROM and a 6-day lagging RR of 1.079 (95% CI: 1.005-1.159) for term PROM; Exposure to a high diurnal temperature variation (diurnal temperature variation greater than 16 °C) was positively correlated with the term PROM. Compared with the 2.5th percentile diurnal temperature variation (2 °C), exposure to the 95th percentile diurnal temperature variation (17 °C) significantly increased the risk of term PROM (RR: 1.229, 95% CI: 1.029-1.467).

CONCLUSIONS

Exposure to a high-temperature and a high diurnal temperature variation environment will increase the relative risks of PROM. For pregnant women in the 3rd trimester, it is important to reduce exposure to extremely high-temperatures and greater diurnal temperature changes.

Association of the maternal serum albumin level with fetal growth and fetal growth restriction in term-born singletons: a prospective cohort study

OBJECTIVE

To investigate the association of the maternal serum albumin (MAlb) level with fetal growth and fetal growth restriction (FGR) risk in term-born singletons.

DESIGN

Prospective cohort study.

SETTING

Four hospital maternity units of the Tongji Maternal and Child Health Cohort study initiated from September 2013 to April 2016 at Wuhan City, in central China.

PATIENT(S)

A total of 3,065 mother-offspring pairs.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Fetal growth was evaluated by birth weight (BW) and birth length. Fetal growth restriction was defined as BW below the 10th percentile.

RESULT(S)

All MAlb levels were within the upper limit of normal. After adjustment for liver function parameters, inflammatory indicators, and others, a reverse U-shaped relationship between MAlb and fetal growth was observed. Specifically, BW increased significantly with an increasing MAlb level when the MAlb level was <36.1 g/L (per g/L: β = 36.8; 95% CI, 0.8, 72.7) but decreased with increasing the MAlb level when the MAlb level was >36.1 g/L (per g/L: β = -15.1; 95% CI, -21.2, -8.9). There was a similar association between MAlb and birth length. Furthermore, the adjusted odd ratios of FGR across increasing tertiles of the MAlb levels were 1.0 (reference), 1.1 (0.7, 1.8), and 1.7 (1.0, 2.6).

CONCLUSION(S)

There was a reverse U-shaped association between MAlb and fetal growth. A higher MAlb level was associated with an increased risk of FGR.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03099837.

Risk factors associated with stress symptoms during pregnancy and postpartum: integrative literature review

Stressful events during prenatal and postpartum have been associated with an increase in the susceptibility to the onset of various diseases, threatening mental and physical health of mother and baby. The aim of this study was to synthesize and analyze the literature related to risk factors associated with stress symptoms during pregnancy and immediate postpartum by means of an integrative review. The search was conducted from January 2013 to July 2020, consulting the following databases: PubMed, PsycINFO, CINAHL, Web of Science and LILACS. In total, 1,677 studies were identified, resulting in 38 articles included in this review. The risk factors most associated with stress in pregnancy and postpartum were related to emotional factors (including mental health, traumatic events and obstetric complications); social and economic factors; mother's health conditions and life style behaviors, and social support and partner related stress. The results are discussed under the light of the biopsychosocial model, which proposes that biological, psychological, and social domains should be considered in order to minimize psychosocial risk conditions. It is concluded that strategies to promote psychological care, education, additional social support and health behaviors should be considered to prevent adverse birth outcomes and to increase maternal well-being.

Association between Physiological Equivalent Temperature (PET) with adverse pregnancy outcomes in Ahvaz, southwest of Iran

Background

There are few epidemiological studies on the relation between temperature changes and adverse pregnancy outcomes. The purpose of this study was to determine the relation between Physiological Equivalent Temperature (PET) with adverse pregnancy outcomes including stillbirth, low birth weight (LBW), preterm labor (PTL), spontaneous abortion (SA), preeclampsia and hypertension in Ahvaz, Iran.

Methods

Distributed Lag Non-linear Models (DLNM) combined with quasi-Poisson regression were used to investigate the effect of PET on adverse pregnancy outcomes. In this study the effect of time trend, air pollutants (NO₂, SO₂ and PM₁₀), and weekdays were adjusted.

Results

High PET (45.4 C°, lag = 0) caused a significant increase in risk of stillbirth. Also, high levels of PET (45.4, 43.6, 42.5 C°, lag = 0–6) and low levels of PET (9.9, 16.9 C°, lags = 0, 0–13, 0–21) significantly increased the risk of LBW. But, low levels of PET (6.4, 9.9, 16.9 C°, lags = 0–6, 0–13) reduced the risk of gestational hypertension.

Conclusion

The results of this study showed that hot and cold thermal stress may be associated with increased risk of stillbirth, and LBW in Ahvaz.

The impact of maternal stress on offspring birth weight and the mediating effect of dietary patterns: the Shanghai Maternal-Child Pairs Cohort study

BACKGROUND

Maternal stress and nutrition during pregnancy are two of the most commonly studied factors in the context of fetal development. However, few investigators have considered the combined effects of stress and diet in pregnant women and their offspring.

AIMS

To determine the impact of maternal stress on offspring birth weight, and the potential mediating role of maternal dietary patterns.

METHODS

A total of 3542 pregnant women and their singleton live births were recruited from Shanghai Maternal-Child Pairs Cohort (Shanghai MCPC). Maternal stress was assessed using the Life Event Scale for Pregnant Women (LESPW) in early and late pregnancy. Food frequency questionnaire (FFQ) was performed to evaluate maternal diet in late pregnancy. Multiple linear regression was conducted to estimate the associations between maternal stress and child birth weight. Logistic regression was performed to calculate the association between maternal stress and small for gestational age (SGA)/large for gestational age (LGA). The bootstrap method was used to investigate the mediating effects of maternal dietary patterns.

RESULTS

Maternal subjective events stress (β = 0.367) and total stress (β = 0.079) in early pregnancy, and positive objective life events stress (β = 0.275) in late pregnancy, were positively associated with birth weight. Maternal dietary pattern of "high-fat and sugar" mediated the associations between subjective events stress and total stress during early pregnancy and birth weight. An increased risk for LGA was observed among women exposed to relatively higher stress during early pregnancy (OR, 1.416; 95% CI, 1.035-1.937). No statistically significant associations were found between maternal stress during late pregnancy and child birth weight or SGA/LGA.

CONCLUSIONS

Maternal life events stress during early pregnancy significantly increases neonatal birth weight and risk for LGA, which may mediate by a "high-fat and sugar" dietary pattern.

LIMITATIONS

The lack of biological markers limits the explanation of the mechanism. The assessment of diet used food intake frequency to evaluate dietary characteristics, which may miss information of energy intake.

Prenatal Maternal Low Selenium, High Thyrotropin, and Low Birth Weights

In consideration of the potential roles of selenoproteins in thyroid function, we aimed to evaluate the association of low selenium status with hypothyroidism during pregnancy and the association of maternal low thyroid function with infant birth size. We conducted a prospective birth cohort study in Shanghai in 2010 and investigated 1931 pregnant mothers of gestational weeks 28-36. Maternal serum selenium and thyrotropin (TSH) levels were determined and birth weights and lengths of newborns were measured. Other covariates were obtained through maternal interviews and medical records. A non-linear association was observed between maternal selenium and TSH levels. Two-piecewise multivariable linear regression models were therefore applied to assess the association of serum selenium with TSH levels, and multivariable linear regression models were applied to assess the association of TSH levels with birth weight/length. Adjusting for potential confounders, when maternal serum selenium levels < 103.7 μg/L (P25th), each unit increase in selenium levels (μg/L) was significantly associated with a decrease of 0.014 μIU/mL in TSH levels (β = - 0.014, 95%CI - 0.025, - 0.002, P = 0.023). However, when selenium levels ≥ 103.7 μg/L, there were no significant relationships between selenium and TSH (β = 0.000, 95%CI - 0.001, 0.002, P = 0.859). Maternal TSH levels were significantly inversely associated with infant birth weight (β = - 0.060, 95%CI - 0.100, - 0.010, P = 0.010). We observed a non-linear association between maternal selenium status and TSH levels. Low selenium status during pregnancy may associate with low thyroid function that was related with low birth weights. Graphical abstract .

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

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.

Newborn amygdalar volumes are associated with maternal prenatal psychological distress in a sex-dependent way

Maternal psychological distress during pregnancy (PPD)1 has been associated with changes in offspring amygdalar and hippocampal volumes. Studies on child amygdalae suggest that sex moderates the vulnerability of fetal brains to prenatal stress. However, this has not yet been observed in these structures in newborns. Newborn studies are crucial, as they minimize the confounding influence of postnatal life. We investigated the effects of maternal prenatal psychological symptoms on newborn amygdalar and hippocampal volumes and their interactions with newborn sex in 123 newborns aged 2-5 weeks (69 males, 54 females). Based on earlier studies, we anticipated small, but statistically significant effects of PPD on the volumes of these structures. Maternal psychological distress was measured at gestational weeks (GW)2 14, 24 and 34 using Symptom Checklist-90 (SCL-90, anxiety scale)3 and Edinburgh Postnatal Depression Scale (EPDS)4 questionnaires. Newborn sex was found to moderate the relationship between maternal distress symptoms at GW 24 and the volumes of left and right amygdala. This relationship was negative and significant only in males. No significant main effect or sex-based moderation was found for hippocampal volumes. This newborn study provides evidence for a sex-dependent influence of maternal psychiatric symptoms on amygdalar structural development. This association may be relevant to later psychopathology.

Time series analysis of total and direct associations between high temperatures and preterm births in Detroit, Michigan

OBJECTIVES

Preterm births (PTBs) represent significant health risks, and several studies have found associations between high outdoor temperatures and PTB. We estimated both the total and natural direct effects (independent of particulate matter, ozone and nitrogen dioxide air pollutants) of the prior 2-day mean apparent temperature (AT) on PTB. We evaluated effect modification by maternal age, race, education, smoking status and prenatal care.

DESIGN AND SETTING

We obtained birth records and meteorological data for the Detroit, Michigan, USA area, for the warm months (May to September), 1991 to 2001. We used a time series Poisson regression with splines of AT, wind speed, solar radiation and citywide average precipitation to estimate total effects. To accommodate multiple mediators and exposure-mediator interactions, AT inverse odds weights, predicted by meteorological and air pollutant covariates, were added in a subsequent model to estimate direct effects.

RESULTS

At 24.9°C relative to 18.6°C, 10.6% (95% CI: 3.8% to 17.2%) of PTBs were attributable to the total effects of AT, and 10.4% (95% CI: 2.2% to 17.5%) to direct effects. Relative excess risks of interaction indicated that the risk of PTB with increasing temperature above 18.6°C was significantly lower among black mothers and higher among mothers less than 19, older than 30, with late or no prenatal care and who smoked.

CONCLUSION

This additional evidence of a direct association between high temperature and PTB may motivate public health interventions to reduce extreme heat exposures among pregnant women, particularly among those who may have enhanced vulnerability.

Sedentary behavior relates to mental distress of pregnant women differently across trimesters: An observational study in China

BACKGROUND

The independent effect of sedentary behavior (SB) on maternal mental health is still unclear. The purpose of this study was to examine the different relationships of SB with maternal distress in pregnant women across the three trimesters, controlling for the confounding factors including physical activity (PA), diet and gestational weight gain.

METHODS

Survey data were collected from 1272 participants in different trimesters of pregnancy. The data were divided into three data sets based on trimester, and regression analysis was conducted on each data set. Both the linear and quadratic relationships between SB and mental distress were estimated.

RESULTS

There was no significant association between SB and any mental distress symptoms in the first trimester. In the second trimester, SB was positively associated with higher mental overall distress symptoms (β=0.34, P < 0.001), including depress and anxiety. There is an inverted-U shaped curvilinear relationship between SB and mental distress in the third trimester, as SB-squared is significantly associated with mental overall distress (GSI: β=-0.65, P = 0.002, depression: β=-0.53, P = 0.014, anxiety: β=-0.46, P = 0.031).

LIMITATIONS

The data were collected from only one city in China, which may limit the generalizability of the findings for all Chinese women. This was an observational study and causality cannot be established.

CONCLUSION

This study found that the relationship between SB and maternal mental distress depends on trimesters. The stage of pregnancy should be considered when designing interventions for pregnant women to change SB to reduce mental distress.

Geographic, Demographic, and Temporal Variations in the Association between Heat Exposure and Hospitalization in Brazil: A Nationwide Study between 2000 and 2015

BACKGROUND

Limited evidence is available regarding the association between heat exposure and morbidity in Brazil and how the effect of heat exposure on health outcomes may change over time.

OBJECTIVES

This study sought to quantify the geographic, demographic and temporal variations in the heat–hospitalization association in Brazil from 2000–2015.

METHODS

Data on hospitalization and meteorological conditions were collected from 1,814 cities during the 2000–2015 hot seasons. Quasi-Poisson regression with constrained lag model was applied to examine city-specific estimates, which were then pooled at the regional and national levels using random-effect meta-analyses. Stratified analyses were performed by sex, 10 age groups, and 11 cause categories. Meta-regression was used to examine the temporal change in estimates of heat effect from 2000 to 2015.

RESULTS

For every 5°C increase in daily mean temperature during the 2000–2015 hot seasons, the estimated risk of hospitalization over lag 0-7 d rose by 4.0% [95% confidence interval (CI): 3.7%, 4.3%] nationwide. Estimated 6.2% [95% empirical CI (eCI): 3.3%, 9.1%] of hospitalizations were attributable to heat exposure, equating to 132 cases (95% eCI: 69%, 192%) per 100,000 residents. The attributable rate was greatest in children [Formula: see text] and was highest for hospitalizations due to infectious and parasitic diseases. Women of reproductive age and those [Formula: see text] had higher heat burden than men. The attributable burden was greatest for cities in the central west and the inland of the northeast; lowest in the north and eastern coast. Over the 16-y period, the estimated heat effects declined insignificantly at the national level.

CONCLUSIONS

In Brazil's hot seasons, 6% of hospitalizations were estimated to be attributed to heat exposure. As there was no evidence indicating that thermal adaptation had occurred at the national level, the burden of hospitalization associated with heat exposure in Brazil is likely to increase in the context of global warming. https://doi.org/10.1289/EHP3889.

Prenatal maternal stress, fetal programming, and mechanisms underlying later psychopathology-A global perspective

There is clear evidence that the mother's stress, anxiety, or depression during pregnancy can alter the development of her fetus and her child, with an increased risk for later psychopathology. We are starting to understand some of the underlying mechanisms including the role of the placenta, gene-environment interactions, epigenetics, and specific systems including the hypothalamic-pituitary-adrenal axis and cytokines. In this review we also consider how these effects may be different, and potentially exacerbated, in different parts of the world. There can be many reasons for elevated prenatal stress, as in communities at war. There may be raised pregnancy-specific anxiety with high levels of maternal and infant death. There can be raised interpersonal violence (in Afghanistan 90.2% of women thought that "wife beating" was justified compared with 2.0% in Argentina). There may be interactions with nutritional deficiencies or with extremes of temperature. Prenatal stress alters the microbiome, and this can differ in different countries. Genetic differences in different ethnic groups may make some more vulnerable or more resilient to the effects of prenatal stress on child neurodevelopment. Most research on these questions has been in predominantly Caucasian samples from high-income countries. It is now time to understand more about prenatal stress and psychopathology, and the role of both social and biological differences, in the rest of the world.

Cold-induced protein RBM3 orchestrates neurogenesis via modulating Yap mRNA stability in cold stress

RBM3 plays a protective role in embryonic neurogenesis. This study finds that maternal cold stress affects the embryonic brain development via RBM3 and Yap. When RBM3 is knocked down or knocked out under the maternal cold stress, the embryonic neurogenesis was impaired.

In mammals, a constant body temperature is an important basis for maintaining life activities. Here, we show that when pregnant mice are subjected to cold stress, the expression of RBM3, a cold-induced protein, is increased in the embryonic brain. When RBM3 is knocked down or knocked out in cold stress, embryonic brain development is more seriously affected, exhibiting abnormal neuronal differentiation. By detecting the change in mRNA expression during maternal cold stress, we demonstrate that Yap and its downstream molecules are altered at the RNA level. By analyzing RNA-binding motif of RBM3, we find that there are seven binding sites in 3′UTR region of Yap1 mRNA. Mechanistically, RBM3 binds to Yap1-3′UTR, regulates its stability, and affects the expression of YAP1. RBM3 and YAP1 overexpression can partially rescue the brain development defect caused by RBM3 knockout in cold stress. Collectively, our data demonstrate that cold temperature affects brain development, and RBM3 acts as a key protective regulator in cold stress.