Unvaccinated Moms Face 2-4% COVID-19 infections Higher Risk of Preterm Birth! Learn How Fast-Track Vaccination Saved Thousands of Babies

A typical human pregnancy spans COVID-19 infections  approximately 40 weeks, with preterm birth, occurring before 37 weeks, posing an elevated risk of infant mortality and enduring health issues. The third trimester exposure to SARS-CoV-2, the virus responsible for COVID-19, has been associated with an increased likelihood of preterm birth. Although vaccines targeting SARS-CoV-2 have proven safe and effective during pregnancy, their impact on reducing the risk of preterm birth remained uncertain.

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In a recently funded study involving researchers such as Dr. Florencia Torche from Stanford University and Dr. Jenna Nobles from the University of Wisconsin-Madison, an in-depth exploration of this question was undertaken. The investigation, covering births in California hospitals from 2014 to 2023, benefited from the state’s meticulous tracking of COVID testing in expectant mothers starting June 2020. This tracking offered a precise estimation of infections during labor and delivery in hospitals with universal testing. The findings were detailed in the December 5, 2023, edition of Proceedings of the National Academy of Sciences.

COVID-19 infections

The researchers adopted a unique approach by analyzing siblings to assess the impact of COVID-19 infections, accounting for other factors influencing the risk of preterm birth, such as socioeconomic status, race, ethnicity, and individual risk factors. The analysis revealed that COVID-19 infection increased the risk of preterm birth from 7.1% to 8.3% between July 2020 and February 2023. This escalation in risk was comparable to that observed with extensive exposure to high-intensity wildfire smoke over three weeks.

The most substantial effect of maternal COVID-19 infection on preterm birth occurred in 2020, witnessing a 5.4% rise in preterm birth rates between July and November. In 2021, characterized by waves of infections from different variants, COVID-19 infection increased the probability of preterm birth by approximately 2-4%. Interestingly, the impact of COVID-19 infection on preterm birth disappeared in 2022.

To ascertain the influence of vaccination, the researchers compared the effect of COVID-19 infection on preterm births in areas with the fastest and slowest vaccine uptake. Zip codes with rapid vaccine uptake (86% vaccination rate by March 2022) exhibited a sharp decline in preterm birth rates, unlike slow-uptake areas (51% vaccination rate during the same period). Until May 2021, the impact of COVID-19 infection on preterm birth rates was similar between these areas, but subsequently diverged, strongly suggesting that vaccination played a crucial role in the variation.

By the close of 2022, the impact of COVID-19 on preterm births had diminished, despite the emergence of the Omicron variant. The widespread availability of vaccines, effective COVID-19 therapies, the emergence of new variants, and increased population immunity to SARS-CoV-2 contributed to this decline.

As SARS-CoV-2 continues to evolve, the necessity for updated booster shots to maintain high immunity levels is anticipated. Presently, booster uptake among pregnant individuals lags behind that of the general population. Dr. Jenna Nobles emphasizes, “There is minimal evidence of adverse effects of vaccination on fetal development. The results presented here strongly indicate that the real risk to the fetus lies in not getting vaccinated. Early vaccination likely averted thousands of preterm births in the U.S. by boosting immunity faster.”