Extreme heat exposure during pregnancy has been linked to an increased risk of severe maternal morbidity (SMM), according to a new study.
SMM — characterised as severe and unanticipated circumstances during labour and delivery — is significantly correlated with prolonged heat exposure during the third trimester of pregnancy.
Long-term heat exposure was linked with a 27 per cent increase in the risk of SMM, found the study published in the journal JAMA Network Open on September 7, 2023.
Pregnant people with “lower educational attainment” and whose pregnancies began during the cold season had higher risks, the study added.

Age also played a part, with pregnant women under the age of 25 and those over the age of 35 showing an elevated risk.“Adolescent mothers are more likely to be in unfavourable social or physical conditions and may have limited knowledge or awareness to protect themselves against extreme heat,” it read.
“Pregnancy complications and risk factors can be more common among older mothers, possibly due to the physiological changes from aging, which may exacerbate heat effects,” the research added.
The analysis conducted at Kaiser Permanente Southern California, an integrated healthcare organisation, between January 1, 2008 and December 31, 2018, found extreme heat has been associated with many adverse obstetric outcomes. This includes preterm birth, premature rupture of membranes, low birth weight and stillbirth.
ADVERTISEMENT
CONTINUE READING BELOW
To provide new insights for SMM prevention, the analysis focused on environmental risk factors that have not been examined previously.
The study, which included 403,602 pregnancies with a mean age of 30.3 years, measured the proportion of different heat days — moderate, high or extreme heat during each pregnancy and by trimester to determine long-term heat exposure.
Short-term exposures, meanwhile, were calculated using heatwaves of varying durations during the last week of pregnancy.
It identified nearly 3,446 SMM cases among the 403,602 pregnancies. Moreover, high exposure to extreme heat days during the third trimester of pregnancy was associated with a 28 per cent increase in risk of SMM.
The timing of conception, leading to the stage of pregnancy during the hottest months, may influence the relationship between heat exposure and SMM.
ADVERTISEMENT
CONTINUE READING BELOW
The mothers who started pregnancy in the cold season (November through April) were more vulnerable to heat exposure. They had higher associations between heat exposure and SMM than those who started pregnancy in the warm season (May-October).
Dear Reader,
Over the past four years, EastMojo revolutionised the coverage of Northeast India through our sharp, impactful, and unbiased coverage. And we are not saying this: you, our readers, say so about us. Thanks to you, we have become Northeast India’s largest, independent, multimedia digital news platform.
Now, we need your help to sustain what you started.
We are fiercely protective of our ‘independent’ status and would like to remain so: it helps us provide quality journalism free from biases and agendas. From travelling to the remotest regions to cover various issues to paying local reporters honest wages to encourage them, we spend our money on where it matters.
Now, we seek your support in remaining truly independent, unbiased, and objective. We want to show the world that it is possible to cover issues that matter to the people without asking for corporate and/or government support. We can do it without them; we cannot do it without you.
Support independent journalism, subscribe to EastMojo.
Thank you,
Karma Paljor
Editor-in-Chief, eastmojo.com
The document also listed associations between heat exposure and cardiovascular events during labour and pregnancy. It suggested the need for targeted interventions to reduce SMM risk, particularly among mothers with low socioeconomic status.
This article is written by Madhumita Paul and republished from DownToEarth. Read the original article here.
Also Read | 3 held with 1,800 rounds of AK-47 bullets in Mizoram