Study finds Covid-19 vaccines do not increase miscarriage risk

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  • New research investigated the risk of miscarriage after receiving Covid-19 vaccines.
  • The study cohort was vaccinated with either Pfizer, Moderna or J&J vaccines.
  • The study compared women who had miscarriages with those with ongoing pregnancies.

New research has found that pregnant women who received at least one Covid-19 vaccine shot did not have an increased risk of miscarriage.

The study published in Jama Network is a case-control surveillance of Covid-19 vaccination during pregnancy and miscarriages.


The study authors identified 105 446 pregnancies using data from eight healthcare systems in the United States. They used these data sets to identify and assign gestational ages for miscarriages and ongoing pregnancies.

The researchers divided the surveillance into seven four-week periods from 15 December 2020 until 28 June 2021. They identified ongoing pregnancies between six and 19 weeks gestation for each four-week surveillance period. Miscarriages were assigned to a four-week surveillance period based on their outcome date.

The women had to have been vaccinated with either the Pfizer, Moderna or J&J vaccine during pregnancy and before 20 weeks gestation.

They analysed the women's medical records 28 days before getting a Covid-19 vaccine and 28 days after vaccination.

Risk results 

The study findings show that the risk of miscarriage did not increase after Covid-19 vaccination compared with ongoing pregnancies.

The study also found that the number of miscarriages was higher in women aged 35 to 49 years.

The researchers note that their results are consistent with previous studies that observed pregnant women who received mRNA vaccines. They say that these data can be used to inform vaccine recommendations and counsel patients.

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