Study finds COVID-19 caused surge in premature births
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Key takeaways:
- A study found a link between COVID-19 and a surge in premature births in California.
- The surge has disappeared as of 2022, likely due to the availability of vaccines.
COVID-19 caused a surge in premature births in California that “fully disappeared” by 2022, likely because of vaccines, researchers reported in the Proceedings of the National Academy of Sciences of the United State of America.
Mothers are advised to receive a COVID-19 vaccine during pregnancy to protect their infants from the effects of SARS-CoV-2.
“This is still an evolving epidemic, and the rate of vaccine boosters among pregnant people right now is very low,” Jenna Nobles, PhD, director of the Center for Demography and Ecology in the department of sociology at the University of Wisconsin-Madison, said in a press release. “The question is, How many more iterations of viral evolution does this need to escape the immunity that we have?”
Nobles and Florencia Torche, PhD, a professor in the School of Humanities and Sciences at Stanford University, measured the impact of the pandemic on preterm births using records for California’s nearly 40 million people, which included information on birth timing and the comparison of sibling births to assist in controlling for the pandemic’s impacts on different demographic groups. Around 12% of all U.S. births occur in California, according to the authors.
As the virus spread from July to November of 2020, the likelihood that a mother infected with COVID-19 in California would give birth 3 or more weeks before her due date was 5.4 percentage points higher than anticipated at 12.3% instead of 6.9%.
To “move the needle on preterm birth that much” is akin to “a disastrous environmental exposure,” Nobles said.
The excess risk for preterm birth fell slightly in early 2021 before dropping steeply in 2022, at which point maternal COVID-19 infection in pregnancy caused no excess risk of preterm birth for infants.
“In ZIP codes with the highest vaccination rates, the excess risk of preterm birth declines much faster,” Nobles said. “By summer 2021, having COVID-19 in pregnancy had no effect on preterm birth risk in these communities. It takes almost a year longer for that to happen in the ZIP codes with the lowest vaccine uptake. That highlights how protective COVID vaccines have been. By increasing immunity faster, early vaccination uptake likely prevented thousands of preterm births in the U.S.”
The authors also found an increase of nearly 38% in the risk for very preterm birth — before 32 weeks — when a child is likely to need neonatal intensive care, “with the possibility of developmental delays and serious implications for their families as well,” Nobles said.
Nobles said it was “miraculous and incredible that we’re now down to essentially zero additional preterm births, but it does not indicate that it’s going to be that way in perpetuity.”
“One big contributor to vaccine hesitancy is that people are worried about safety for the fetus and about the ability to get pregnant,” Nobles said. “We already know there is very little evidence of adverse effects of vaccination on fetal development. The results here are compelling evidence that what will actually harm the fetus is not getting vaccinated. That’s a message practitioners can share with concerned patients.”
References:
Study: Spike in premature births caused by COVID, halted by vaccines. https://www.eurekalert.org/news-releases/978113. Published Nov. 27, 2023. Accessed Nov. 30, 2023.
Torche F, et al. Proc Natl Acad Sci U S A. 2023;doi: 10.1073/pnas.2311573120.
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