Further Observations on Pregnancy Complications and COVID-19 Infection

To the Editor Studies have assessed the risk of adverse outcomes in pregnant women with COVID-19 infection compared with either pregnant women without COVID-19 infection, as in Villar et al, or women with COVID-19 infection who were not pregnant. Finding an appropriate reference group is a challenge for both study types. In Villar et al, COVID-19 diagnosis was defined as laboratory confirmation of infection or the presence of symptoms. The reference group was pregnant women without a COVID-19 diagnosis; a negative test result was not required because most countries did not perform universal testing in pregnancy. As the authors noted, this definition may result in exposure misclassification, which tends to bias results toward the null.
Source: JAMA Pediatrics - Category: Pediatrics Source Type: research