Utilizing Datasets to Advance Perinatal Research

Potential missed opportunities for antenatal corticosteroid exposure and outcomes among periviable births: observational cohort study

OBJECTIVE

Test the hypothesis potential missed opportunities for antenatal corticosteroids increase as gestational age decreases and are associated with adverse outcomes.

DESIGN

Observational cohort study.

SETTING

24 US centers in the Neonatal Research Network.

POPULATION

Actively treated infants 22-25 weeks' gestation and birth weight 401-1000 grams, without major birth defects, born 2006-2018.

METHODS

Potential missed opportunity was defined as no antenatal corticosteroids but did have prenatal antibiotics, and/or magnesium sulfate, and/or prolonged rupture of membranes. Poisson regression models adjusted for baseline characteristics.

MAIN OUTCOME MEASURES

Antenatal corticosteroid exposure, mortality, and severe intracranial hemorrhage or periventricular leukomalacia.

RESULTS

6966 (87.5%) were exposed to antenatal corticosteroids, 454 (5.7%) had no exposure but potential missed opportunities for antenatal corticosteroid exposure, and 537 (6.7%) had no exposure and no evidence of potential missed opportunities. Compared with infants born at 25 weeks, potential missed opportunities for antenatal corticosteroid exposure were more likely at 22 weeks (adjusted relative risk (aRR) [95% CI] 11.06 [7.52-16.27]) and 23 weeks (3.24 [2.44-4.29]) but did not differ at 24 weeks (1.08 [0.82-1.42]). Potential missed opportunities for antenatal corticosteroids decreased over time at 22-23 weeks' gestation. Antenatal corticosteroid exposed infants had lower risk of death (31.0% vs 54.8%; 0.77 [0.70-0.84]) and survivors had lower risk of severe brain injury (25.0% v 44.5%; 0.64 [0.55-0.73]) compared with infants with potential missed opportunities.

CONCLUSION

Potential missed opportunities for antenatal corticosteroid exposure increased with decreasing gestational age and were associated with higher rates of death and severe brain injury among actively treated periviable births.

Accurate identification of cohort study designs in perinatal research: a practical guide

Study designs are often mischaracterized in the obstetrics literature; in particular, the designation of studies as retrospective (historical) cohorts is frequently in error to describe studies that are prospective cohorts. This is especially true for studies based on electronic health records, which often should be properly considered as prospective cohorts. Epidemiologic study designs were developed in earlier eras of research and healthcare when researchers directly contacted study participants or relied on data from paper medical records. Accordingly, standard epidemiologic study design definitions are difficult to apply to digitized data, which have become common in the modern era of healthcare and computing. In this article, we briefly review the characteristics of the 3 main types of cohort studies. Afterward, we build on existing definitions by proposing several subdesignations of prospective cohort studies that we believe will reduce the confusion in terminology. We provide illustrative examples from obstetrics to concretely demonstrate connections and distinctions among study designs. First, a prospective cohort study can be "active" (participants are deliberately and explicitly enrolled in a prospective research study) or "passive" (participants are followed up in real time for some nonresearch activity, such as clinical care or quality improvement). An active prospective cohort study never stops being a prospective cohort study; however, when reused to answer a new, secondary question, we propose that this should be called a "reused (active) prospective cohort." The de novo cohort study that answered the original question should be considered an "intended (active) prospective cohort." Lastly, when a randomized controlled trial is reused to study some new questions where the randomization variable is not under study, this is also a subtype of a prospective cohort study, a "repurposed randomized controlled trial." The use of more detailed descriptors to describe prospective cohort studies will enable more accurate identification of this study design going forward. It is likely that further refinements will be needed in the future, given the ongoing evolution of how we engage with patients or participants and how data are collected, stored, and linked.

Influence of midwifery presence in United States centers on labor care and outcomes of low-risk parous women: A Consortium on Safe Labor study

BACKGROUND

Sixty percent of United States births are to multiparous women. Hospital-level policies and culture may influence intrapartum care and birth outcomes for this large population, yet have been poorly explored using a large, diverse sample. We sought to use national United States data to analyze the association between midwifery presence in maternity care teams and the birth processes and outcomes of low-risk parous women.

METHODS

We conducted a retrospective cohort study using Consortium on Safe Labor data from low-risk parous women in either interprofessional care (n = 12 125) or noninterprofessional care centers (n = 8996). Unadjusted, adjusted (age, race, health insurance type), propensity-adjusted, and propensity-matched logistic regression models were used to assess processes and outcomes.

RESULTS

There was concordance in outcome differences across regression models. With propensity score matching, women at interprofessional centers, compared with women at noninterprofessional centers, were 85% less likely to have labor induced (risk ratio [RR] 0.15; 95% CI 0.14-0.17). The risk for primary cesarean birth among low-risk parous women was 36% lower at interprofessional centers (RR 0.64; 95% CI 00.52-0.79), whereas the likelihood of vaginal birth after cesarean for this population was 31% higher (RR 1.31; 95% CI 1.10-1.56). There were no significant differences in neonatal outcomes.

CONCLUSIONS

Parous women have significantly higher rates of vaginal birth, including vaginal birth after cesarean, and lower likelihood of labor induction when cared for in centers with midwives. Our findings are consistent with smaller analyses of midwifery practice and support integrated, team-based models of perinatal care to improve maternal outcomes.

Historical (retrospective) cohort studies and other epidemiologic study designs in perinatal research

When investigators describe the study design they employed, the term retrospective cohort commonly is selected and commonly used incorrectly. In a prospective cohort, investigators enroll exposed and unexposed individuals, all of whom are at risk of experiencing the study outcome, and follow them forward in time to observe incident outcomes. In a retrospective (historical) cohort, investigators use preexisting data to identify exposed and unexposed individuals in the past, without regard to outcome status, and trace these individuals forward, up to and possibly including the present, to determine incident outcomes. Both of these designs are cohorts because they identify individuals based on exposure, without regard to outcome; they follow the individuals over time, either in the future (prospective cohort) or in the past (historical cohort), and they assess the incidence, not just the prevalence, of the study outcome. The designation of retrospective cohort is based on the presence and timing of follow up before the onset of research, not on the timing of the analysis with respect to when the data were collected and regardless of the original purpose for which the data were collected. In short, a prospective cohort study remains a prospective cohort study when analyzed for secondary research purposes, even if this research occurs many years after data collection. Because of the complex nature of modern databases and study designs and the inherent ambiguity of the terms retrospective and prospective, modern epidemiologists rarely use these terms as simple descriptors, preferring instead to describe what the study actually did.