Vaccine against covid-19 during pregnancy: Protection against premature birth and stillbirth, says study | Health & well-being

New study revealed yet another benefit of the covid-19 vaccine for pregnant women. Vaccination during pregnancy can reduce the chances of premature birth and stillbirth, according to a study published in March in the medical journal Journal of Clinical Medicine. The research also showed that there is a greater risk of fetal death and premature birth when the infection occurred in the first half of pregnancy, drawing attention to the importance of obstetric monitoring and immunization.

Furthermore, the research revealed that the presence of mild symptoms seems to have little relevance, on the other hand, severe symptomatic cases that require treatment and hospitalization are significant risk factors for premature birth and stillbirth. These complications were also more observed during the waves of the Alpha and Delta variants compared to Ômicron.

To reach this conclusion, the researchers analyzed data collected from more than 8,000 women from Germany and Austria who contracted the coronavirus at any time during their pregnancy, between April 2020 and December 2022. Of this group, 26.8% of pregnant women were vaccinated against Covid-19 at the time of infection.

Risk of stillbirth

In total, 70 patients (0.87%) were stillborn after 20 weeks of gestation. But, in vaccinated women, the fetal death rate was almost half that of the unvaccinated group: 0.51% versus 1.04%. Furthermore, there was a difference in relation to the moment in pregnancy when the woman contracted the virus. The stillbirth rate was higher in cases where the pregnant woman was infected early in pregnancy (1.47%) compared to an infection in the third trimester (0.49%).

“Pregnant women are around three to four times more likely to develop severe forms of Covid-19 when comparing the risk of death, complications and illness in a pregnant woman with a non-pregnant woman. This is because women are more restricted in the use of medications during pregnancy and it is more difficult to manage respiratory failure. Therefore, there are many more unfavorable outcomes for pregnant women than non-pregnant women”, explains Renato Kfouri, pediatric neonatologist and infectious disease specialist, president of the Immunization Department of the Brazilian Society of Pediatrics (SBP) and columnist for CRESCER. “In addition, infections are capable of triggering miscarriage in early pregnancy or fetal death in the second half of pregnancy,” he adds.

Risk of premature birth

In total, 835 pregnant women (10.39%) had premature births, that is, they gave birth before 37 weeks. The researchers divided between “early preterm birth” – before 32 weeks – which corresponded to 165 (2.05%) of births, and “late preterm birth” – between 32 and 36 gestational weeks, which corresponded to 670 (8 .43%) of cases.

Vaccinated pregnant women represented only 1.25% of early premature births and 6.54% of late premature births. In relation to those who were not vaccinated, more than twice as many had premature births before 32 weeks (2.66%) and 9.43% gave birth between the 32nd and 36th week of pregnancy.

In the case of infection at the beginning of pregnancy, the rate of premature birth before 32 weeks was higher: 3.63% versus 1.05% of women who contracted the virus at the end of pregnancy. On the other hand, in cases of late infection, the rate of premature birth between 32 and 36 weeks was higher: 9.32% compared to 6.80% after infection early in pregnancy.

“Infections generally cause systemic inflammation, which can alter placental circulation. This can contribute to placental abruption, bleeding or early uterine contraction that leads to premature labor”, explains Kfouri.

Differences between variants

The stillbirth rate was higher during the Alpha (which emerged in September 2020) and Delta (October 2020) periods: 1.56% in both periods, almost three times higher than during the Ômicron wave (November 2021 ), which corresponded to 0.53% of cases.

Regarding childbirth, the rate of women who gave birth before 32 weeks was higher among those infected in the Alpha and Delta periods: 3.13% and 3.44% versus 1.39% during the Ômicron period. But the rate of pregnant women who gave birth between the 32nd and 36th gestational weeks was lower during the Omicron period, at 7.35%, compared to the Alpha and Delta waves, 9.40% and 8.56%, respectively. .

But, for Renato Kfouri, this does not indicate that one variant is more worrying than another. “Probably what causes pregnant women to have less severe conditions is vaccination. The Alpha and Delta variants appeared more at the beginning of the pandemic, when vaccines were not yet released for pregnant women in some countries. Nowadays, we have fewer cases serious because people have already contracted the virus before and have several doses of vaccine in their bodies, what we call hybrid immunity”, says the infectious disease specialist. “The study confirms the risks that we already know and reinforces the importance of vaccinating pregnant women”, he concludes.