Wei et al. have published a meta-analysis (MA), which aimed to evaluate the association between SARS-CoV-2 infection during pregnancy and adverse pregnancy outcomes. Using classical random-effects model, they found that SARS-CoV-2 infection was associated with preeclampsia, preterm birth and stillbirth. Performing MA with low event rates or with few studies may be challenging insofar as MA relies on several within and between-study distributional assumptions. The objective was to assess the robustness of the results provided by Wei et al.

We performed a sensitivity analysis using frequentist and Bayesian meta-analysis methods. We also estimated fragility indexes.

For eclampsia, the confidence intervals of most frequentist models contain 1. All beta-binomial models (Bayesian) lead to credible intervals containing 1. The prediction interval, based on DL method, ranges from 0.75 to 2.38. The fragility index is 2 for the DL method. For preterm, the confidence (credible) intervals exclude 1. The prediction interval is broad, ranging from 0.84 to 20.61. The fragility index ranges from 27 to 10. For stillbirth, the confidence intervals of most frequentist models contain 1. Six Bayesian MA models lead to credible intervals containing 1. The prediction interval ranges from 0.52 to 8.49. The fragility index is 3.

Given the available data and the results of our broad sensitivity analysis, we can suggest that SARS-CoV-2 infection during pregnancy is associated with preterm, and that it may be associated with preeclampsia. For stillbirth, more data are needed as none of the Bayesian analyses are conclusive.