Unvaccinated women with COVID are more likely to lose foetuses and infants, Scottish data shows

Miriam Leah Zisman at her home in the Midwood neighbourhood of Brooklyn on May 27, 2021. Zisman, 23, has opted not to receive the COVID-19 vaccine while pregnant. The New York Times
The risk of losing a baby through stillbirth or the first month of life was highest among women who delivered their babies within four weeks of the onset of a COVID-19 infection: 22.6 deaths for every 1,000 births, four times the rate in Scotland of 5.6 deaths per 1,000 births.

All of those deaths occurred in pregnancies among unvaccinated women, the researchers found. “Quite strikingly, no baby deaths occurred in women who had SARS-CoV-2 and were vaccinated,” said the paper’s first author, Dr Sarah J Stock, a maternal-fetal medicine specialist at the University of Edinburgh Usher Institute in Exeter.

The study also found a higher rate of preterm birth among women diagnosed with COVID-19, a rate that spiked if the baby was born within a month of the mother falling ill. More than 16% of these women gave birth before 37 weeks of pregnancy, compared with 8% among other women.

In Scotland, as in the United States, vaccination rates of pregnant women are low. Only one-third of pregnant women are vaccinated against the coronavirus, despite the protections afforded by immunisation. Early research has found no evidence that the Pfizer or Moderna vaccines pose serious risks during pregnancy.

Indeed, the Scottish study found that the vast majority of infections among pregnant women were in those who were completely unvaccinated or were only partially vaccinated. Only 11% of the total infections were reported among fully vaccinated pregnant women.

Pregnant women who were unvaccinated were also four times as likely to be hospitalised, compared with vaccinated pregnant women.

Stock and her colleagues analysed data collected by the COVID-19 in Pregnancy in Scotland study, a national cohort of all women who were pregnant or became pregnant after March 1, 2020, through the end of October 2021. The team tracked 144,546 pregnancies in 130,875 women during this period.

One weakness of the study is that the authors did not adjust for confounding factors, like maternal age or preexisting medical conditions, which could lead to poor pregnancy outcomes regardless of coronavirus infection or COVID-19 diagnosis (they also did not know whether women who were hospitalis¹1¹¹¹¹¹¹ed were admitted because of COVID-19 disease or were just incidentally found to test positive at admission).

Vaccination rates are low among pregnant women across the board but are particularly low among younger women and those from lower socioeconomic backgrounds, the study noted. Future analyses will take these demographic factors and other confounding factors into account, the authors said.

Still, the discrepancies in hospitalization, premature birth and infant loss rates between vaccinated and unvaccinated women are so marked that those adjustments are unlikely to alter the conclusions, Stock and her colleagues said.

They urged pregnant women to get vaccinated, echoing the pleas of health officials in the United States.

“The key take home we’d love to get across is that really the best way to protect mother and baby is vaccination at the earliest opportunity, and that can be done at any stage of pregnancy,” said Aziz Sheikh, a population health researcher at the University of Edinburgh and another of the paper’s authors.

“We have enough information to bring the really strong message around promoting vaccination in pregnancy now,” said Rachael Wood, a consultant in public health medicine in Public Health Scotland and a member of the study team.

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