The risk of stillbirth is almost doubled in pregnant women infected with Covid-19, according to a US CDC study (Centers for Disease Control and Prevention), who renew their call for vaccination before or during their pregnancy.
The analysis focused on data from more than 1.2 million deliveries between March 2020 and September 2021 and recorded in the hospital database. Two periods are distinguished: before the arrival of the Delta variant (from March 2020 to June 2021) and after it has become predominant in the United States (from July to September 2021).
Over the whole period, stillbirths (from the 20th week) remained rare and represented 0.65% of births, or about 8,154 stillbirths. But 273 stillbirths (1.26%) occurred among the 21,653 deliveries of women with Covid-19 and 7,881 (0.64%) among the 1,227,981 deliveries without Covid-19. The authors stress that they were not able to determine the vaccination status of the patients, nor the date of infection (before or at the time of hospitalization).
Increased risk with Delta
It remains that “The adjusted risk of stillbirth was higher for deliveries with Covid-19 compared to deliveries without Covid-19 between March 2020 and September 2021 (RR adjusted to 1.90)”, with a difference between the periods before Delta (RR adjusted to 1.47) and after Delta (RR adjusted to 4.04), it is indicated.
In detail, several factors were associated with an increased risk of stillbirth for deliveries with Covid-19: chronic hypertension, multiple pregnancy, adverse cardiac event, placental abruption, sepsis, acute respiratory distress syndrome, mechanical ventilation and admission to intensive care. . For each of these risk factors, “Associations were stronger during Delta’s dominance period”, is it noted.
“Further studies are needed to examine the role of maternal complications linked to Covid-19 on the risk of stillbirth”, insist the authors, recalling that a review on pregnancies complicated by infection by Sars-CoV-2 identified placental histopathologic abnormalities, suggesting that placental hypoperfusion and inflammation could occur. “These results could, in part, explain the association between Covid-19 and stillbirth”, they continue. And, “Comparisons of placental results (before / after Delta, Editor’s note) could improve the understanding of the biological reasons for the observed differences”, is it added.
Recommended booster dose
In order to reduce the impact of Covid-19 on stillbirths, the authors recall the importance of prevention strategies “Evidence-based, including vaccination before or during pregnancy”.
In France, the booster dose is not mandatory for pregnant women, but is strongly recommended, as pointed out by Prof. Jean-François Delfraissy, President of the Scientific Council, last week.
The French National College of Gynecologists and Obstetricians (CNGOF) and the Research Group on Infections During Pregnancy (CRIG) deem it necessary “Regardless of the term of pregnancy, when the initial regimen dates from more than 6 months”.
Pregnant women, recognized as a risk group for severe forms by the High Council for Public Health (HCSP) and the High Authority for Health (HAS), are “Particularly vulnerable” facing Covid-19, especially in the event of comorbidity. “Compared to an uninfected pregnant woman, there is a risk multiplied by 18 of admission to intensive care, by 2.8 of fetal loss, by 5 of admission of the newborn to intensive care and more if comorbidity”, recalls a communicated of CNGOF.