Exposure to high and low temperatures during pregnancy may slow down the growth of the fetus

A researcher at the Azrieli Faculty of Medicine at Baylan University led a nationwide Israeli study of more than 600,000 newborns.

The study, published in the journal Environmental Health Perspectives, assessed the critical window period during which 624,940 single-born babies nationwide in Israel are susceptible to extreme low temperatures and high temperatures during pregnancy and fetal growth during 2010-2014

The research was led by Dr.

The researchers collected, mapped, modeled, and analyzed all recorded live birth data, residential information at birth, and outdoor temperature throughout pregnancy

Record live births

The birth certificate data for all live births comes from the National Registry of Births and Birth Defects of the Ministry of Health

Mapping residential information

The birth address is geocoded using geocoding services, such as HERE and Google, and the Israeli attribute mapping database GZIRNET, or converted to geographic coordinates

Hot, cold, hot or cold

According to data from the Israel Meteorological Agency, the daily temperature is estimated based on a time-space model with fine resolution scales (one-hour and one-square-kilometer resolution)

Climate zone division

Israel’s highly variable climate is determined by altitude, latitude, and location close to the Mediterranean.

Statistical Analysis

For each region, according to the distribution of all women in the cohort living in the climatic zone, the average daily temperature in different time periods (such as days, weeks, three months, and the entire pregnancy) is converted into percentiles

Next, the researchers conducted a statistical analysis to evaluate the relationship between temperature and birth weight, and based on the newborn’s race, religious group, gender, mother’s marital status, origin, age, education, socioeconomic class, and employment status.

result

A consistent association was observed between high temperature and low temperature and fetal birth weight

The correlation analysis between the monthly average birth weight of the three gas zones and the regional specific temperature percentile shows that the correlation between the coldest and warmest temperatures and the lower monthly average birth weight is lower than the intermediate temperature of each distribution

From the average temperature throughout pregnancy, the reverse U-shaped pattern is obvious

The three-month specific association also shows a reverse U-shaped pattern, with the strongest association estimated to be the extreme temperature in the third trimester
.
The negative correlation between full-term birth weight and the coldest and warmest temperatures was also significant in the first three months and the middle three months, but was weaker than the corresponding estimates for the third month
.

Analysis and recommendations

"Our research shows that in all full-term babies born in Israel within five years, there is a significant association between exposure to high and low temperature outdoor environments and birth weight
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Low birth weight may indicate abnormal intrauterine growth, which is early childhood and throughout life.
Is a risk factor for morbidity," said Dr.
Keren Agay-Shay, director of the HER laboratory of the Azrieli School of Medicine at Baylan University
.
"In our research, we used a new high-resolution space-time model that has not been used before
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When stratified by city and geocoding level, when estimating daily minimum and maximum temperatures When categorizing exposure based on the temperature distribution of 49 natural areas, when all live births (including preterm births and birth defects) are estimated, the association pattern is consistent
.
” Agay-Shay added
.

Determining the susceptible window period during pregnancy can clarify the underlying mechanisms and potential strategies to reduce the risk of pregnant women being exposed to extreme temperatures
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Research estimates indicate that 3-36 weeks is the potential window period that is susceptible to cold, the most relevant is the 36th week, and 3-9 weeks and 19-34 weeks are the potential window periods that are susceptible to high temperature
.

As the temperature rises due to climate change, the researchers emphasized that public health organizations are recommended to develop strategies to address these challenges at the national and community levels
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In addition, identifying windows that are susceptible to temperature can help clinicians construct and refine the set of recommendations they provide to pregnant women
.

This research was funded by the Israel Science Foundation
.

Article title

Low and High Ambient Temperatures during Pregnancy and Birth Weight among 624,940 Singleton Term Births in Israel (2010–2014): An Investigation of Potential Windows of Susceptibility