Abstract
BACKGROUND: The association between pregnant patients participating in obstetrical studies and pregnancy outcomes is understudied. OBJECTIVE: This study aimed to evaluate the association between participation in obstetrical studies and maternal and neonatal outcomes. STUDY DESIGN: This was a retrospective cohort study of all patients delivering at a single center from 2013 to 2018. Patients with pregnancy loss at <13 weeks of gestation or major fetal anomalies were excluded. Patients who enrolled in one or more obstetrical studies were categorized as "study participants" and were compared with patients who did not enroll in an obstetrical study, that is, "study nonparticipants." The primary outcome was a composite of maternal morbidity diagnosed up to 6 weeks after delivery. The secondary outcomes included composite neonatal morbidity and other perinatal outcomes. Bivariate analyses compared baseline demographics and outcomes between groups. Multivariable logistic regression was used to estimate adjusted odds ratios with 95% confidence intervals. Subgroup analyses by study design (trial or observational) were planned. RESULTS: Of 19,569 patients included in this analysis, 3848 (19.7%) were study participants, and 15,721 (80.3%) were study nonparticipants. Among study participants, 3023 (78.6%) enrolled in a trial, and 825 (21.4%) enrolled in an observational study. The study participants had higher body mass index and were more likely to be younger, non-Hispanic Black, publicly insured, nulliparous, and undergo cesarean delivery than study nonparticipants. Compared with study nonparticipants, the study participants had significantly lower odds of composite maternal morbidity (9.2% vs 8.7%; adjusted odds ratio, 0.83; 95% confidence interval, 0.73-0.95) and composite neonatal morbidity (27.5% vs 18.6%; adjusted odds ratio, 0.53; 95% confidence interval, 0.48-0.58). In addition, the odds of fetal death, 5-minute Apgar score of <5, neonatal death, maternal and neonatal intensive care unit admissions, and lengths of stay were lower for study participants than for study nonparticipants. In stratified analyses, maternal morbidity was only significantly decreased among trial participants; however, there was a significantly reduced odds of neonatal morbidity, regardless of study design (trial or observational vs no study). CONCLUSION: Participation in obstetrical studies was associated with decreased maternal and neonatal morbidities after adjusting for potential confounders. This underscored the importance of pregnant patients enrolling in obstetrical clinical studies and potentially benefiting from the additional surveillance. Further study of how study participation exerts this effect on pregnancy outcomes is warranted.