Do women expecting twins have a worse maternal outcome when infected with SARS-CoV-2 during pregnancy in comparison to singleton pregnancies? Data from the COVID-19 Related Obstetric and Neonatal Outcome Study (CRONOS)

Introduction Studies have shown that pregnant women with COVID-19 have a worse outcome than non-pregnant women. Pregnancy associated physiological changes in respiratory function including alteration in lung volumes and capacities due to the mechanical impediment caused by the growing fetus, could influence the course of COVID-19. Women carrying twins could consequently be more vulnerable to severe COVID-19 disease in comparison to women with singleton pregnancies.

Methods A total of 5514 women with a SARS-Cov 2 infection during pregnancy registered in the COVID-19 Related Obstetric and Neonatal Outcome Study (CRONOS) were included. The single COVID-19 related maternal outcomes (hospitalisation, oxygen supplementation, admission to intensive care unit, pneumonia, thromboembolic episode or death) as well as the combined outcome in 165 twin and 5349 singleton pregnancies were compared. Singleton pregnancies with increased intraabdomimal pressure (macrosomia or polyhydramion) were excluded. Multivariate logistic regression was used to estimate the odds ratios and 95% confidence intervals for combined adverse maternal outcome.

Results Frequency of dyspnea, likelihood to develop dyspnea in a defined pregnancy week as well as duration of the symptomatic phase did not differ between the two groups. Yet, in women expecting twins, combined outcome occurred on average earlier during pregnancy in comparison to singleton pregnancies. The incidence of single COVID-19-associated maternal outcomes as well as the combined outcome was comperable between the two groups. However, regression analysis revealed that multiple gestation, BMI>30 (before pregnancy) and gestational age contributed significantly to the increased risk for adverse combined maternal outcome. On the other hand, age and medically assisted reproduction were not significant risk factors for adverse combined maternal outcome.

Conclusion Our data show that multiple gestation alone is a risk factor for COVID-19-associated adverse combined maternal outcome. Moreover, severe courses of COVID-19 in women expecting twins are observed earlier in pregnancy in comparison to singleton pregnancies. This could be attributed to the more evident displacement of the diaphragm by the enlarged uterus in comparison to singleton pregnancies.

Publication History

Article published online:
15 November 2023