Analyzing Uncontrolled Confounding of the Perinatal Health Effects of Severe Acute Respiratory Syndrome Coronavirus 2 Infection During Pregnancy

Abstract

To the Editor—We thank Pei-Yun et al [ 1] for their interest in our article [ 2]. They raised some issues with our study not controlling for some potential confounders and not addressing unmeasured effect modifiers that could also be “residual confounders” and claimed that matching on time-dependent propensity score would reduce such residual confounding.