As are the cases of influenza and whooping cough, pregnant women can protect themselves and their babies from Covid-19 by receiving vaccines and forming antibodies, a U.S. study has shown.

Antibody formation levels were highest at the third stage of pregnancy, it said. However, there was little relationship between vaccination and gestation period, meaning all pregnant women can benefit themselves and their babies by getting jabs at any time.

Researchers at Weill Cornell Medicine in New York City recently published a paper that revealed the relationship between the Covid-19 vaccination period and the development of the immune system within mothers and babies in the latest issue of Obstetrics & Gynecology.

The researchers analyzed the post-natal antibody levels (anti-spike IgG) according to pregnant women’s vaccination period based on the data of 1,359 vaccinated pregnant women and 1,362 umbilical cord blood. Mothers were inoculated before (up to six weeks) and during pregnancy with the vaccines of Pfizer, Moderna, and Johnson & Johnson, and 20 were boosted, too.

The result found that the vaccination period during pregnancy did not have much to do with the antibody formation levels of mothers and babies.

The antibody levels were highest among mothers and their cord blood who received vaccines at the third stage of pregnancy (from the 28th week to birth). However, they did not show much difference from mothers vaccinated in early pregnancy or even weeks before pregnancy who showed relatively high levels of antibodies, suggesting protective effects.

Mothers infected with Covid-19 showed a little higher antibody levels than average in their bodies and cord blood at the time of delivery. However, they showed much less antibody reduction due to the early vaccination.

The 20 women who reported they had received booster shots at the third stage of pregnancy showed higher antibody levels on average. In contrast, those who had not completed vaccination until delivery had far lower antibody levels than the fully vaccinated group, and the same went for their cord blood.

Pregnant women must not put off vaccination until late in pregnancy, the paper said. On the other hand, if they take booster shots in late pregnancy, it can sharply raise antibody levels.

“The key message of this study is women can always receive vaccine shots during pregnancy, which is beneficial for both mothers and babies at the time of childbirth,” said Professor Yawei Jenny Yang of the Pathology Department at Weill Cornell Medical. “In addition, vaccination in early phases can protect mothers and babies throughout pregnancy.”

Meanwhile, according to existing studies, pregnant women infected with Covid-19 have higher risks of developing into severe conditions. The novel coronavirus also increases the danger of premature birth, stillbirth, and other negative results.