Washington, Jan 5 (IANS): Covid-19 vaccination during pregnancy was not associated with complications at birth such as preterm birth or babies born underweight, according to a study published by the US Centers for Disease Control and Prevention (CDC).

Pregnant women with Covid-19 are at increased risk for severe illness and adverse birth outcomes, yet many remain reluctant to be vaccinated.

To explore the effect of Covid vaccines in pregnancy, the CDC evaluated 46,079 pregnant women in the US between December 15, 2020 and July 22, 2021.

Among more than 10,000 women who received at least one dose of a Covid-19 vaccine, the rates of preterm birth were 4.9 per cent compared to 7.0 per cent for roughly 36,000 unvaccinated women, researchers said in the CDC's Morbidity and Mortality Weekly Report published on Tuesday.

Further, the report also showed that Covid vaccination did not increase the risk of delivering a baby who weighed less than usual for the number of weeks of pregnancy.

These data support the safety of Covid-19 vaccination during pregnancy, said Heather S. Lipkind, from Yale University, US, in the report.

"Covid-19 vaccination during pregnancy was not associated with preterm birth or small-for-gestational-age at birth overall, stratified by trimester of vaccination, or number of vaccine doses received during pregnancy, compared with unvaccinated pregnant women," Lipkind added.

Women with symptomatic Covid-19 during pregnancy have a more than two-fold increased risk for intensive care unit admission, invasive ventilation, and extracorporeal membrane oxygenation, and a 70 per cent increased risk for death, compared with nonpregnant women with symptomatic infections.

Thus, the CDC recommends Covid-19 vaccination for women who are pregnant, recently pregnant, who are trying to become pregnant now, or who might become pregnant in the future.

However, vaccination coverage among pregnant women has been low due to concerns regarding vaccine safety.

In the CDC report, the women became pregnant between May and October of 2020, before vaccines were available.

Nearly all who were vaccinated got the shots in their second or third trimester of pregnancy. Some 96 per cent of them had received at least one dose of an mRNA vaccine from either Pfizer, or Moderna. The remaining women received the single-shot vaccine from Johnson & Johnson.

There was no difference in outcomes based on the timing of vaccination, or on which mRNA vaccine was received or how many doses.

"Results have consistently shown no increased risk when stratified by mRNA Covid-19 vaccine dose, or by second or third trimester vaccination, compared with risk among unvaccinated pregnant women," Lipkind said.