Température au thermomètre-globe mouillé — Wikipédia


  • The link between extreme heat and preterm birth

    How did we miss this for so long?” Basu asked. “Women are often the last to get studied. But the most vulnerable people are those who are pregnant.


    In the 14 years since Basu’s initial paper, dozens of studies have confirmed that higher temperatures and heat waves are linked to preterm birth as well as stillbirth.

    In 2020, Basu co-authored a review of 57 studies that found a significant association between air pollution and heat exposure with preterm birth and low birth weight. Scientists have found an association between heat exposure and preterm birth rates in every developed nation, and in the few developing nations to conduct studies so far.

    While it’s not yet clear how heat triggers preterm birth, there are several hypotheses — including dehydration, hormonal releases that rupture membranes surrounding the fetus, or poor blood flow between parent and unborn child.

    This research has taken place against a backdrop of a worsening maternal health crisis in the U.S., particularly in marginalized communities. The U.S. has the highest rate of preterm births in the developed world. Kasey Rivas, associate director of strategic partnerships at the March of Dimes and a co-author of a recent report on birth outcomes and disparities, told me that maternal health disparities in the U.S. stem largely from systemic racism and are worsening due to climate change.


    Obstetric providers in low-income communities of color describe preterm birth as a crisis. “Preterm birth is a 24/7, 365-days-a-year public health emergency in my community,” said Nneoma Nwachuku Ojiaku, an obstetrician in Sacramento. Madeleine Wisner, who was the only midwife provider serving low-income residents in the Sacramento Valley through the state Medicaid program for seven years until recently, described something similar. “A course of maternity care where nothing abnormal happens doesn’t exist any longer in the populations I was serving,” Wisner said. She’s seen a range of birth complications — including abnormally implanted placentas, umbilical cord abnormalities, and preeclampsia — in patients who were exposed to heat, air pollution, or wildfire smoke during pregnancy.


    There seems to be this myth of endless adaptation,” said Chandni Singh, a climate researcher at the Indian Institute for Human Settlements. “In tropical countries that are already very hot, there is this continuous expectation to adapt, which is not feasible. You can’t adapt to 45 C” (113 degrees F). And heat has knock-on impacts. “Heat doesn’t come alone; it comes with water scarcity and wildfires,” she said, emphasizing the need to curtail greenhouse gas emissions.


    A March study of 17 federal, 38 state, and 19 city websites with heat-health information found that only seven websites listed pregnant people as vulnerable or at-risk populations.

    We are more likely to see information on how to take care of pets during heat waves than pregnant women,” Ojiaku told me.

    In addition, she said, creating green spaces such as parks in neighborhoods that have been subject to systemic racism and redlining can offer shade, cool spaces to exercise, and a buffer against air pollution.

    Sacramento is called ‘the city of trees,’ but that’s for a select few in the predominantly wealthier sections of Sacramento,” Ojiaku said. “Other areas are a concrete jungle.

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