Expectant mothers are seven times more likely to give birth prematurely if they contract Covid-19 late in pregnancy, according to a new study.
Researchers found that Covid-19 is linked to an increased risk of preterm birth, but only for women infected in their last trimester.
They advised women over 34 weeks pregnant to wear masks and practice social distancing to reduce the risk of infection.
The study of more than 5,000 pregnant women is one of the first to look at pregnancy outcomes for Covid patients by trimester.
However, the Israeli research team found no difference in the odds of losing a baby between infected and uninfected women.
Previous studies of Covid during pregnancy have been small, generally limited to patients who are hospitalized, and often have not reported outcomes dependent on infection at different stages of pregnancy.
Biostatistician and epidemiologist Noga Fallach and her colleagues at the Kahn-Sagol-Maccabi Research and Innovation Center used anonymized data collected by Maccabi Healthcare Services in Israel to identify 2,753 women who became infected during pregnancy, with 2,753 women not reported Matching Covid-19 infections.
The study ran from February 21, 2020 to July 2 last year.
Of the infected women, 17.4 percent contracted Covid in the first trimester, 34.2 percent in the second and 48.4 percent in the third trimester.
First and second trimester Covid infection was not associated with an increased risk of preterm birth.
However, women who became infected in the third trimester were 2.76 times more likely to have a preterm birth – while women infected after 34 weeks of pregnancy were more than seven times more likely to have a preterm birth.
The results published in the journal Plus oneshowed a lower rate of bladder rupture before labor began in infected women (39.1 percent) compared to uninfected women (58.3 percent), and the rates of cesarean sections and baby losses were similar in the two groups.
Because of the increased risk of preterm birth in women who become infected during late pregnancy, the researchers suggest that during their third trimester, and particularly after 34 weeks of pregnancy, they should be instructed to maintain social distancing and wear masks to reduce the risk of infection reduce.
dr Tal Patalon, head of the research centre, said: “The results are encouraging and reassuring that being infected with Covid-19 during pregnancy is not associated with any type of pregnancy loss.
“However, it should be remembered that the research group tested the Covid pre-delta variants and does not refer to the variant that is dominant today, which is Omicron.”
She added, “We continue to conduct research to provide real-world data and knowledge to the public and decision-makers.”