ABSTRACT
OBJECTIVE: This article evaluates the impact of adopting a practice of elective induction of labor (eIOL) at 39 weeks among nulliparous, term, singleton, vertex (NTSV) pregnancies in a statewide collaborative. STUDY DESIGN: We used data from a statewide maternity hospital collaborative quality initiative to analyze pregnancies that reached 39 weeks without a medical indication for delivery. We compared patients who underwent an eIOL versus those who experienced expectant management. The eIOL cohort was subsequently compared with a propensity score-matched cohort who were expectantly managed. The primary outcome was cesarean birth rate. Secondary outcomes included time to delivery and maternal and neonatal morbidities. Chi-square test, t-test, logistic regression, and propensity score matching methods were used for analysis. RESULTS: In 2020, 27,313 NTSV pregnancies were entered into the collaborative's data registry. A total of 1,558 women underwent eIOL and 12,577 were expectantly managed. Women in the eIOL cohort were more likely to be ≥35 years old (12.1 vs. 5.3%, p < 0.001), identify as white non-Hispanic (73.9 vs. 66.8%, p < 0.001), and be privately insured (63.0 vs. 61.3%, p = 0.04). When compared with all expectantly managed women, eIOL was associated with a higher cesarean birth rate (30.1 vs. 23.6%, p < 0.001). When compared with a propensity score-matched cohort, eIOL was not associated with a difference in cesarean birth rate (30.1 vs. 30.7%, p = 0.697). Time from admission to delivery was longer for the eIOL cohort compared with the unmatched (24.7 ± 12.3 vs. 16.3 ± 11.3 hours, p < 0.001) and matched (24.7 ± 12.3 vs. 20.1 ± 12.0 hours, p < 0.001) cohorts. Expectantly managed women were less likely to have a postpartum hemorrhage (8.3 vs. 10.1%, p = 0.02) or operative delivery (9.3 vs. 11.4%, p = 0.029), whereas women who underwent an eIOL were less likely to have a hypertensive disorder of pregnancy (5.5 vs. 9.2%, p < 0.001). CONCLUSION: eIOL at 39 weeks may not be associated with a reduced NTSV cesarean delivery rate. KEY POINTS: · Elective IOL at 39 weeks may not be associated with a reduced NTSV cesarean delivery rate.. · The practice of elective induction of labor may not be equitably applied across birthing people.. · Further research is needed to identify best practices to support people undergoing labor induction..
ABSTRACT
An individual's antibody titers to influenza A strains are a result of the complicated interplay between infection history, cross-reactivity, immune waning, and other factors. It has been challenging to disentangle how population-level patterns of humoral immunity change as a function of age, calendar year, and birth cohort from cross-sectional data alone. We analyzed 1,589 longitudinal sera samples from 260 children across three studies in Nicaragua, 2006-16. Hemagglutination inhibition (HAI) titers were determined against four H3N2 strains, one H1N1 strain, and two H1N1pdm strains. We assessed temporal patterns of HAI titers using an age-period-cohort modeling framework. We found that titers against a given virus depended on calendar year of serum collection and birth cohort but not on age. Titer cohort patterns were better described by participants' ages relative to year of likely introduction of the virus's antigenic cluster than by age relative to year of strain introduction or by year of birth. These cohort effects may be driven by a decreasing likelihood of early-life infection after cluster introduction and by more broadly reactive antibodies at a young age. H3N2 and H1N1 viruses had qualitatively distinct cohort patterns, with cohort patterns of titers to specific H3N2 strains reaching their peak in children born 3 years prior to that virus's antigenic cluster introduction and with titers to H1N1 and H1N1pdm strains peaking for children born 1-2 years prior to cluster introduction but not being dramatically lower for older children. Ultimately, specific patterns of strain circulation and antigenic cluster introduction may drive population-level antibody titer patterns in children.
