Preterm birth during an extreme weather event in Québec, Canada: a "natural experiment"

Trends in adverse pregnancy outcomes in Louisiana, 2017 to 2022

Natural disasters can lead to more adverse pregnancy outcomes (APO). It is unclear if the extended COVID-19 pandemic has impacted APOs and pre-existing conditions among perinatal populations with increased risk of severe maternal morbidity and mortality.A retrospective chart review was conducted of hospital records and birth certificates in the largest birth hospital in Louisiana from 2017 to 2022. Amongst 27,877 births (50.9% White, 38.3% Black, 28.9 ± 5.6 years), gestational diabetes (GDM) was lowest in pre-pandemic conceptions (11.0%, June 2017-May 2019) and rose to 16.4% early pandemic (October 2019-February 2020) but leveled off at 12.2% in peak (March 2020-February 2021) and late pandemic (March 2021-September 2021). Individuals who conceived in early and peak pandemic were 47% (95% CI 33, 63) and 11% (95% CI 2, 20) more likely to develop GDM respectively, compared to pre-pandemic conceptions. Individuals who delivered during early (aRR: 1.54, 95% CI 1.33-1.78), peak (aRR: 1.48, 95% CI 1.32-1.65), and late (aRR: 1.62, 95% CI 1.41, 1.85) pandemic were more likely to develop preeclampsia and HELLP syndrome compared to pre-pandemic conceptions. Individuals were also 17% (95% CI 5, 32) more likely to enter pregnancy with chronic hypertension in peak pandemic compared to pre-pandemic. In paired analysis (n = 3390), individuals with a pandemic conception that occurred early pandemic had a higher risk of developing GDM compared to their pre-pandemic pregnancy (aOR 3.26, 95% CI 1.52, 6.97). Supporting birthing individuals amongst significant stressful events, especially in early gestation, is critical for preventing APOs and severe maternal morbidity and mortality.

Exposure to acute ambient temperature extremes and neonatal intensive care unit admissions: A case-crossover study

BACKGROUND

Extreme in utero temperatures have been associated with adverse birth outcomes, including preterm birth and low birthweight. However, there is limited evidence on associations with neonatal intensive care unit (NICU) admissions, which reflect a range of poor neonatal health outcomes.

METHODS

This case-crossover study assesses the associations between ambient temperature changes during the week of delivery and risk of NICU admission. Data from the Consortium on Safe Labor (2002-2008) were linked to ambient temperature at hospital referral regions. Adjusted hazard ratios (HR) and 95 % confidence intervals (CI) estimated NICU admission risk with a 1 °C increase on each day of the week of delivery and of the average weekly temperature, adjusted for particulate matter ≤2.5 μm (PM2.5) and relative humidity. We also estimated associations with 1 °C increases and 1 °C decreases in temperatures during weeks of site-specific extreme heat (>90th and 95th percentiles) and cold (<5th and 10th percentiles), respectively.

RESULTS

There were 27,188 NICU admissions with median (25th, 75th) temperature of 16.4 °C (5.8, 23.0) during the week before delivery. A 1 °C increase in temperature during the week of delivery was not associated with risk of NICU admission. However, analyses of extreme temperatures found that a 1 °C decrease in weekly average temperatures below the 10th and 5th percentiles was associated with 30 % (aHR = 1.30, 95 % CI 1.28, 1.31) and 47 % (aHR = 1.47, 95 % CI 1.45, 1.50) increased risk of NICU admissions, while a 1 °C increase in weekly average temperatures above the 90th and 95th percentiles was associated with more than two- (aHR = 2.29, 95 % CI 2.17, 2.42) and four-fold (aHR = 4.30, 95 % CI 3.68, 5.03) higher risk of NICU admission, respectively.

CONCLUSIONS

Our study found temperature extremes in the week before delivery increased NICU admission risk, particularly during extreme heat, which may translate to more adverse neonatal outcomes as extreme temperatures persist.

Changes in preterm birth during the COVID-19 pandemic by duration of exposure and race and ethnicity

OBJECTIVE

We aimed to determine whether coronavirus-disease-2019 (COVID-19) pandemic exposure duration was associated with PTB and if the pandemic modified racial disparities.

STUDY DESIGN

We analyzed Philadelphia births and replicated in New Haven. Compared to matched months in two prior years, we analyzed overall PTB, specific PTB phenotypes, and stillbirth.

RESULTS

Overall, PTB was similar between periods with the following exceptions. Compared to pre-pandemic, early pregnancy (&lt;14 weeks') pandemic exposure was associated with lower risk of PTB &lt; 28 weeks' (aRR 0.60 [0.30-1.10]) and later exposure with higher risk (aRR 1.77 [0.78-3.97]) (interaction p = 0.04). PTB &lt; 32 weeks' among White patients decreased during the pandemic, resulting in non-significant widening of the Black-White disparity from aRR 2.51 (95%CI: 1.53-4.16) to aRR 4.07 (95%CI: 1.56-12.01) (interaction P = 0.41). No findings replicated in New Haven.

CONCLUSION

We detected no overall pandemic effects on PTB, but potential indirect benefits for some patients which could widen disparities remains possible.

Birth Outcomes, Health, and Health Care Needs of Childbearing Women following Wildfire Disasters: An Integrative, State-of-the-Science Review

BACKGROUND

The frequency and severity of extreme weather events such as wildfires are expected to increase due to climate change. Childbearing women, that is, women who are pregnant, soon to be pregnant, or have recently given birth, may be particularly vulnerable to the effect of wildfire exposure.

OBJECTIVES

This review sought to systematically assess what is known about birth outcomes, health, and health care needs of childbearing women during and after exposure to wildfires.

METHODS

An integrative review methodology was utilized to enable article selection, data extraction, and synthesis across qualitative and quantitative studies. Comprehensive searches of SCOPUS (including MEDLINE and Embase), CINAHL, PubMed, and Google Scholar identified studies for inclusion with no date restriction. Included studies were independently appraised by two reviewers using the Crowe Critical Appraisal Tool. The findings are summarized and illustrated in tables.

RESULTS

Database searches identified 480 records. Following title, abstract, and full text screening, sixteen studies published between 2012 and 2022 were identified for this review. Eleven studies considered an association between in utero exposure to wildfire and impacts on birth weight and length of gestation. One study reported increased rates of maternal gestational diabetes mellitus and gestational hypertension following exposure; whereas one study reported differences in the secondary sex ratio. Two studies reported higher incidence of birth defects following in utero exposure to wildfire smoke. Three studies reported increased mental health morbidity, and one study associated a reduction in breastfeeding among women who evacuated from a wildfire disaster.

DISCUSSION

Evidence indicates that wildfire exposure may be associated with changes to birth outcomes and increased morbidity for childbearing women and their babies. These effects may be profound and have long-term and wide-ranging public health implications. This research can inform the development of effective clinical and public health strategies to address the needs of childbearing women exposed to wildfire disaster. https://doi.org/10.1289/EHP10544.

Threatened abortion, threatened premature labor, and preterm birth during the first state of emergency for COVID-19 in 2020 in Japan

AIM

This study examined the maternal experience of threatened abortion, threatened premature labor, or preterm birth before, during, and after the first state of emergency for COVID-19 in 2020 in Japan.

METHODS

This was a cross-sectional, internet-based questionnaire survey. We recruited 600 postpartum women and divided them into three groups by date of delivery: before (October 2019-March 2020), during (April-May 2020), and after (June-October 2020) the first state of emergency. The outcome was the presence of at least one of the following complications: threatened abortion, threatened premature labor, and/or preterm birth. The prevalence ratios (PRs) of the outcome were calculated and compared among the three groups using a multivariable Poisson regression model with adjustment for potential confounders.

RESULTS

Of the 553 women eligible for analysis, those who delivered during (PR 0.69, 95% confidence interval [CI] 0.47-0.99) and after (PR 0.62, 95% CI 0.42-0.90) the state of emergency were less likely to have experienced either threatened abortion, threatened premature labor, or preterm birth than those who delivered before the state of emergency. Among the adjustment variables, smoking at the time of survey (PR 1.68, 95% CI 1.01-2.80) and living in the prefectures with a population of >5 million (PR 0.71, 95% CI 0.51-0.97) were associated with the study outcome.

CONCLUSION

Threatened abortion, threatened premature labor, or preterm birth appeared to decrease during and after the first state of emergency in 2020. The longitudinal effects of coronavirus disease on maternal and newborn health should be monitored continuously.

Effects of maternal exposure to acute stress on birth outcomes: a quasi-experiment study

Numerous studies have shown associations between maternal stress and poor birth outcomes, but evidence is unclear for causal inference. Natural disasters provide an opportunity to study effects of quasi-randomized hardship with an accurate measure of onset and duration. In a population-based quasi-experimental study, we examined the effect of maternal exposure to the January 1998 Québec ice storm on birth outcomes by comparing pregnant mothers who lived in an area hard hit by the ice storm with those in two unaffected regions. In a total of 147,349 singleton births between 1995 and 2001, we used a difference-in-differences method to estimate the effects of the ice storm on gestational age at delivery (GA), preterm birth (PTB), weight-for-gestational-age z-scores (BWZ), large for gestational age (LGA), and small for gestational age (SGA). After adjusting for maternal and sociodemographic characteristics, there were no differences between the exposed and the unexposed mothers for birth outcomes. The estimated differences (exposed vs. unexposed) were 0.01 SDs (95% CI: -0.02, 0.05) for BWZ; 0.10% point (95% CI: -0.95%, 1.16%) for SGA; 0.25% point (95% CI: -0.78%, 1.28%) for LGA; -0.01 week (95% CI: -0.07, 0.05) for GA; and 0.16% point (95% CI: -0.66%, 0.97%) for PTB. Neither trimester-specific nor dose-response associations were observed. Overall, exposure to the 1998 Québec ice storm as a proxy for acute maternal stress in pregnancy was not associated with poor birth outcomes. Our results suggest that acute maternal hardship may not have a substantial effect on adverse birth outcomes.

Pregnancy outcomes among evacuees of the Sinabung volcano, 2010-2018 (North Sumatra, Indonesia): A matched cohort study

OBJECTIVES

Exposure to natural disasters during pregnancy is associated with adverse birth outcomes and increased probability of female births. Nonetheless, relatively little work has been done on evacuations of women living in close vicinity to volcanic eruptions. We conducted a retrospective cohort study among women from villages near the Sinabung volcano in North Sumatra, Indonesia, which has been active since 2010.

METHODS

We compared an "exposed" sample of women (n = 97) who were pregnant when forced to evacuate their villages due to the volcanic eruptions and an "unexposed" sample of non-evacuees (n = 97) matched for age and year of child's birth. We collected anthropometric data (height and weight of each woman) and conducted structured interviews about pregnancy outcomes and evacuation-related stress.

RESULTS

Evacuation led to an almost five-fold increase in the adjusted odds of having an early or preterm birth in non-imputed (OR = 4.84, 95% CI: 1.31-17.92) and multiply imputed (OR = 4.84, 95% CI: 1.29-19.19) analyses. It also led to approximately a 1 cm decrease in birth length in the non-imputed (β = -1.10, 95% CI: -1.96-0.24) and multiply imputed (β = -1.17, 95% CI: -1.20-0.36) analyses, both including controls for confounders. We found decreasing birth length with increasing stress among evacuees. There was no discernible effect of evacuation or stress on the other outcomes.

CONCLUSIONS

Both adverse effects we documented can exert negative influences on later-in-life outcomes for children of women pregnant during evacuation. This should be considered when developing protocols for supporting women and connecting them with clinical resources when evacuated from natural disasters.

Retirements of Coal and Oil Power Plants in California: Association With Reduced Preterm Birth Among Populations Nearby

Coal and oil power plant retirements reduce air pollution nearby, but few studies have leveraged these natural experiments for public health research. We used California Department of Public Health birth records and US Energy Information Administration data from 2001-2011 to evaluate the relationship between the retirements of 8 coal and oil power plants and nearby preterm (gestational age of <37 weeks) birth. We conducted a difference-in-differences analysis using adjusted linear mixed models that included 57,005 births-6.3% of which were preterm-to compare the probability of preterm birth before and after power plant retirement among mothers residing within 0-5 km and 5-10 km of the 8 power plants. We found that power plant retirements were associated with a decrease in the proportion of preterm birth within 5 km (-0.019, 95% CI: -0.031, -0.008) and 5-10 km (-0.015, 95% CI: -0.024, -0.007), controlling for secular trends with mothers living 10-20 km away. For the 0-5-km area, this corresponds to a reduction in preterm birth from 7.0% to 5.1%. Subgroup analyses indicated a potentially larger association among non-Hispanic black and Asian mothers than among non-Hispanic white and Hispanic mothers and no differences in educational attainment. Future coal and oil power plant retirements may reduce preterm birth among nearby populations.

Temperature exposure during pregnancy and birth outcomes: An updated systematic review of epidemiological evidence

Seasonal patterns of birth outcomes have been observed worldwide, and there was increasing evidence that ambient temperature played as a trigger of adverse birth outcomes, such as preterm birth (PTB), low birth weight (LBW), and stillbirth. To systematically review updated epidemiological evidence about the relationship between temperature exposure during pregnancy and PTB, LBW, and stillbirth, we searched for related studies published in English from electronic databases and references of identified papers. We only included original articles that directly reported the effects of prenatal temperature exposure on birth outcomes. The characteristics and main findings of included studies were examined. A total of 36 epidemiological studies were finally included in this review. Most of these studies focused on PTB and LBW, while less attention has been paid to stillbirth that was relatively rare in the occurrence. Several designs including ecological (e.g., descriptive and time-series) and retrospective cohort studies (e.g., case-crossover and time-to-event) were applied to assess temperature effects on birth outcomes. Temperature metrics and exposure windows varied greatly in these investigations. Exposure to high temperature was generally found to be associated with PTB, LBW, and stillbirth, while several studies also reported the adverse impact of low temperature on birth outcomes of PTB and LBW. Despite no conclusive causality demonstrated, the current evidence for adverse effect on birth outcomes was stronger for heat than for cold. In summary, the evidence linking birth outcomes with ambient temperature was still very limited. Consequently, more related studies are needed worldwide and should be conducted in diversified climate zones, so as to further ascertain the association between temperature and birth outcomes. Future studies should focus on more sophisticated study designs, more accurate estimation of temperature exposure during pregnancy, and more efficient methods to find out the exposure windows, as well as cold-related effects on birth outcomes.

Examining the Effects of Ambient Temperature on Pre-Term Birth in Central Australia

Preterm birth (born before 37 completed weeks of gestation) is one of the leading causes of death among children under 5 years of age. Several recent studies have examined the association between extreme temperature and preterm births, but there have been almost no such studies in arid Australia. In this paper, we explore the potential association between exposures to extreme temperatures during the last 3 weeks of pregnancy in a Central Australian town. An immediate effect of temperature exposure is observed with an increased relative risk of 1%-2% when the maximum temperature exceeded the 90th percentile of the summer season maximum temperature data. Delayed effects are also observed closer to 3 weeks before delivery when the relative risks tend to increase exponentially. Immediate risks to preterm birth are also observed for cold temperature exposures (0 to -6 °C), with an increased relative risk of up to 10%. In the future, Central Australia will face more hot days and less cold days due to climate change and hence the risks posed by extreme heat is of particular relevance to the community and health practitioners.

Assessing health impacts of the December 2013 Ice storm in Ontario, Canada

Background

Ice, or freezing rain storms have the potential to affect human health and disrupt normal functioning of a community. The purpose of this study was to assess acute health impacts of an ice storm that occurred in December 2013 in Toronto, Ontario, Canada.

Methods

Data on emergency department visits were obtained from the National Ambulatory Care Reporting System. Rates of visits in Toronto during the storm period (December 21, 2013 – January 1, 2014) were compared to rates occurring on the same dates in the previous five years (historical comparison) and compared to those in a major unaffected city, Ottawa, Ontario (geographic comparison). Overall visits and rates for three categories of interest (cardiac conditions, environmental causes and injuries) were assessed. Rate ratios were calculated using Poisson regression with population counts as an offset. Absolute counts of carbon monoxide poisoning were compared descriptively in a sub-analysis.

Results

During the 2013 storm period, there were 34 549 visits to EDs in Toronto (12.46 per 1000 population) compared with 10 794 visits in Ottawa (11.55 per 1000 population). When considering year and geography separately, rates of several types of ED visits were higher in the storm year than in previous years in both Toronto and Ottawa. Considering year and geography together, rates in the storm year were higher for overall ED visits (RR: 1.10, 95 % CI: 1.09-1.11) and for visits due to environmental causes (RR: 2.52, 95 % CI: 2.21-2.87) compared to previous years regardless of city. For injuries, visit rates were higher in the storm year in both Toronto and Ottawa, but the increase in Toronto was significantly greater than the increase in Ottawa, indicating a significant interaction between geography and year (RR: 1.23, 95 % CI: 1.16-1.30).

Conclusions

This suggests that the main health impact of the 2013 Ice Storm was an increase in ED visits for injuries, while other increases could have been due to severe weather across Ontario at that time. This study is one of the first to use a population-level database and regression modeling of emergency visit codes to identify acute impacts resulting from ice storms.

Placental Epigenetics in Children's Environmental Health

There is a growing interest in understanding the mechanisms that drive the developmental origins of health and disease, and the role of epigenetic regulation has risen to the forefront of these studies. In particular, the placenta may be a model organ to consider as a mediator of the impact of the environment on developmental programming of children's health, as this organ plays a critical role in directing development and regulating the fetal environment. Several recent studies have begun to examine how environmental toxicant exposures can impact the placental epigenome, focusing on studies of DNA methylation and microRNA expression. This review highlights several of these studies and emphasizes the potential the placenta may hold on the broader understanding of the impact of the intrauterine environment on long-term health.

Effects of wildfire disaster exposure on male birth weight in an Australian population

Background and objectives: Maternal stress can depress birth weight and gestational age, with potential health effects. A growing number of studies examine the effect of maternal stress caused by environmental disasters on birth outcomes. These changes may indicate an adaptive response. In this study, we examine the effects of maternal exposure to wildfire on birth weight and gestational age, hypothesising that maternal stress will negatively influence these measures.

Methodology: Using data from the Australian Capital Territory, we employed Analysis of Variance to examine the influence of the 2003 Canberra wildfires on the weight of babies born to mothers resident in fire-affected regions, while considering the role of other factors.

Results: We found that male infants born in the most severely fire-affected area had significantly higher average birth weights than their less exposed peers and were also heavier than males born in the same areas in non-fire years. Higher average weights were attributable to an increase in the number of macrosomic infants. There was no significant effect on the weight of female infants or on gestational age for either sex.

Conclusions and implications: Our findings indicate heightened environmental responsivity in the male cohort. We find that elevated maternal stress acted to accelerate the growth of male fetuses, potentially through an elevation of maternal blood glucose levels. Like previous studies, our work finds effects of disaster exposure and suggests that fetal growth patterns respond to maternal signals. However, the direction of the change in birth weight is opposite to that of many earlier studies.

The effect of prenatal natural disaster exposure on school outcomes

This study looks at the impact of exposure to natural disasters during pregnancy on the educational outcomes of North Carolina children at the third grade level. A broad literature relates negative birth outcomes to poor educational performance, and a number of recent studies have examined the effect of prenatal exposure to natural disasters on birth outcomes. This study takes the next step by considering how prenatal exposure affects later outcomes. Combining North Carolina administrative data on births and school performance with disaster declarations from the U.S. Federal Emergency Management Agency (FEMA) allows for the identification of children who were exposed to disasters during prenatal development. These children are compared with other children born in the same county who were not exposed to disasters while in utero. Regression results suggest that children exposed to hurricanes prenatally have lower scores on third grade standardized tests in math and reading. Those exposed to flooding or tornadoes also have somewhat lower math scores. Additionally, results suggest that these negative effects are more concentrated among children in disadvantaged subgroups, especially children born to black mothers. However, no evidence exists that these effects are mediated by common measures of birth outcomes, including birth weight and gestational age.

Associations of meteorology with adverse pregnancy outcomes: a systematic review of preeclampsia, preterm birth and birth weight

The relationships between meteorology and pregnancy outcomes are not well known. This article reviews available evidence on the relationships between seasonality or meteorology and three major pregnancy outcomes: the hypertensive disorders of pregnancy (including preeclampsia, eclampsia and gestational hypertension), gestational length and birth weight. In total 35, 28 and 27 studies were identified for each of these outcomes. The risks of preeclampsia appear higher for women with conception during the warmest months, and delivery in the coldest months of the year. Delivery in the coldest months is also associated with a higher eclampsia risk. Patterns of decreased gestational lengths have been observed for births in winter, as well as summer months. Most analytical studies also report decreases in gestational lengths associated with heat. Birth weights are lower for deliveries occurring in winter and in summer months. Only a limited number of studies have investigated the effects of barometric pressure on gestational length or the effects of temperature and sunshine exposure on birth weight, but these questions appear worth investigating further. Available results should encourage further etiological research aiming at enhancing our understanding of the relationships between meteorology and adverse pregnancy outcomes, ideally via harmonized multicentric studies.