What happens in women pregnant after COVID-19 vax?

Vaccination with the ChAdOx1 nCoV-19 vaccine does not affect the rates of fertility, miscarriage, and other birth outcomes in women vaccinated before pregnancy, according to data from four ongoing clinical trials — adding to the body of evidence on the safety of COVID-19 vaccine in these women.    

“Fears of adverse effects of COVID-19 vaccination on fertility have affected vaccine uptake in some communities,” said the researchers from the Oxford COVID Vaccine Trial Group.

“Vaccine hesitancy during pregnancy, or among women of childbearing age, could have substantial public health consequences because infection with SARS-CoV-2 during pregnancy is a risk factor for severe maternal illness and complications,” they explained.

The current analysis reviewed pregnancies that have occurred in four phase I to III clinical trials of ChAdOx1 nCoV-19 (AZD1222) which are still ongoing in three countries: UK, Brazil, and South Africa. Participants in the studies were women of childbearing age (defined as ≤49 years) who were randomized to vaccination with ChAdOx1 nCoV-19 or the control vaccine. These women were not to be pregnant at study entry. Women who were pregnant after vaccination were identified and followed up till 3 months after birth.

During the course of the studies, 121 out of the 9,755 participants (1 percent) got pregnant. [Lancet 2021;doi:10.1016/S0140-6736(21)02282-0]

The researchers did not see any evidence of an association between the ChAdOx1 nCoV-19 vaccine and reduced fertility overall (rates, 0.0102 vs 0.0089; rate ratio [RR], 1.14; p=0.53). Similar finding was seen when the analysis was limited to only women with viable pregnancies (rate, 0.0065 vs 0.0060; RR, 1.08; p=0.80).

There was also no excess risk of miscarriage — defined as loss of pregnancy before 23 weeks of gestation — with ChAdOx1 nCoV-19 vs control (14 percent vs 21 percent; RR, 0.67; p=0.51).

By the time of analysis, 15 livebirths had taken place in total, of which three were preterm births occurring in the ChAdOx1 nCoV-19 group, though these were all in the late preterm stage (34 to 37 weeks of gestation), according to the researchers.

In addition, there were no stillbirths or neonatal deaths seen in either group.

“Fertility was unaffected by vaccination with ChAdOx1 nCoV-19,” concluded the researchers. “There was no increased risk of miscarriage and no instances of stillbirth in women vaccinated before pregnancy in global clinical trials of ChAdOx1 nCoV-19.”

“With increasing availability of misinformation, which continues to affect vaccine uptake, these data, along with published data on mRNA vaccines, can provide evidence to support women in making decisions regarding vaccination,” they said.