LOS ANGELES– In the American Journal of Epidemiology this month, Pregistry shares lessons learned during the execution of the International Registry of Coronavirus Exposure in Pregnancy (IRCEP). The article, titled “International Registry of Coronavirus Exposure in Pregnancy (IRCEP) – Cohort Description and Methodological Considerations,” identifies challenges affecting the study of COVID-19 impacts on pregnant persons, including participant retention and potential bias introduced by participants who enroll after birth. Pregistry is a global leader in the development and conduct of observational studies during pregnancy.
Limited data are available about the potential health effects of infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on pregnant people and their developing offspring. Pregistry developed IRCEP to provide data on the risk of major adverse obstetric and neonatal outcomes among women with varying degrees of severity and timing of COVID-19 exposure during pregnancy. In the recently published article, the research team led by Dr. Diego Wyszynski, Pregistry CEO, and Dr. Sonia Hernandez-Diaz, Professor of Epidemiology at the Harvard T.H. Chan School of Public Health, shares lessons learned. These include implementation challenges for online international pregnancy cohorts, namely retention of prospectively enrolled participants during follow-up. In addition, a key methodological challenge impacting pregnancy cohorts is the potential bias introduced when participants are enrolled retrospectively. As a result, multiple biases need to be considered and addressed when estimating and interpreting the effects of COVID-19 in pregnancy in these types of cohorts.
“The IRCEP remains one of the largest cohorts of pregnant people with COVID-19, and future studies can use our lessons learned to assess a variety of specific research questions related to COVID-19 and pregnancy, such as the effect of COVID-19 severity on multiple outcomes,” said Dr. Wyszynski. “For example, while the biological effects of viruses tend to be universal, the health consequences of COVID-19 among those volunteering to participate in the registry, who tend to be more educated and health conscious, is likely to underestimate the absolute impact on more vulnerable populations.”
To develop the IRCEP, Pregistry enrolled a large international cohort of pregnant people with and without COVID-19. By March 2021, 17,532 participants from 77 countries had enrolled, with 54% of participants enrolling during pregnancy and 46% afterwards. Among those with symptomatic COVID-19 with a positive SARS-CoV-2 test (N=4,934), symptoms were mild in 41%, moderate in 52%, and severe in 7%; while 7.7% were hospitalized for COVID-19 and 1.7% were admitted to an intensive care unit.
“When we generated the IRCEP, our global research team learned that non-random samples selected based on testing can provide valid estimates of COVID-19 effects on pregnancy outcomes if risk factors associated not only with the infection but also with testing are controlled,” said Dr. Wyszynski. “We also confirmed that well-designed social media awareness campaigns are key to enrolling participants in internet-based studies.”
Primary awareness campaigns for the IRCEP were designed to appeal to people of a wide variety of backgrounds; however, the enrolled sample turned out to be more educated than the general population (65% with at least a college education). Also, enrollment in the IRCEP dropped substantially between campaigns, despite a large amount of pregnancy and COVID-19-related resources available on the Pregistry website. While completion of modules among retrospective enrollees was over 70%, retention of participants registered during pregnancy was below 10%. Enrollment after pregnancy outcomes are known may self-select a group with adverse outcomes and more eager to share their experience in a study, thus overestimating risks; or it might underestimate the risk if the distressing event reduces the likelihood of participation.
