Research
Obstetrics
The impact of hospital obstetric volume on maternal outcomes in term, non–low-birthweight pregnancies

https://doi.org/10.1016/j.ajog.2014.09.026Get rights and content

Objective

The impact of hospital obstetric volume specifically on maternal outcomes remains under studied. We examined the impact of hospital obstetric volume on maternal outcomes in low-risk women who delivered non–low-birthweight infants at term.

Study Design

We conducted a retrospective cohort study of term singleton, non–low-birthweight live births from 2007-2008 in California. Deliveries were categorized by hospital obstetric volume categories and separately for nonrural hospitals (category 1: 50-1199 deliveries per year; category 2: 1200-2399; category 3: 2400-3599, and category 4: ≥3600) and rural hospitals (category R1: 50-599 births per year; category R2: 600-1699; category R3: ≥1700). Maternal outcomes were compared with the use of the chi-square test and multivariable logistic regression.

Results

There were 736,643 births in 267 hospitals that met study criteria. After adjustment for confounders, there were higher rates of postpartum hemorrhage in the lowest-volume rural hospitals (category R1 adjusted odds ratio, 3.06; 95% confidence interval, 1.51–6.23). Rates of chorioamnionitis, endometritis, severe perineal lacerations, and wound infection did not differ between volume categories. Longer lengths of stay were observed after maternal complications (eg, chorioamnionitis) in the lowest-volume hospitals (16.9% prolonged length of stay in category 1 hospitals vs 10.5% in category 4 hospitals; adjusted odds ratio, 1.91; 95% confidence interval, 1.01–3.61).

Conclusion

After confounder adjustment, few maternal outcomes differed by hospital obstetric volume. However, elevated odds of postpartum hemorrhage in low-volume rural hospitals raises the possibility that maternal outcomes may differ by hospital volume and geography. Further research is needed on maternal outcomes in hospitals of different obstetric volumes.

Section snippets

Materials and Methods

This was a retrospective cohort study of California deliveries in 2007-2008, with the use of linked vital statistics/patient discharge data. The California Patient Discharge Data, Vital Statistics Birth Certificate Data, and Vital Statistics Death Certificate data are linked and maintained by the Office of Statewide health Planning and Development (OSHPD), Healthcare Information Resource Center, under the California Health and Human Services Agency.25 The dataset contains patient discharge data

Results

There was a total of 267 maternity hospitals in California that met study criteria, with a total of 736,643 deliveries. Two hundred eleven hospitals with 678,622 deliveries were located in nonrural locations, and 56 hospitals were located in rural locations, with 58,021 deliveries (Table 2). The larger hospitals in categories 3 and 4 cared for more black and Asian American women compared with the smallest hospitals (categories 1 and 2), which cared for a larger share of white women (categories

Comment

In this large retrospective cohort of term non–low-birthweight California deliveries, we observed some differences in maternal quality outcomes by hospital volume category. The lowest- and medium-volume rural hospitals exhibited higher rates of postpartum hemorrhage compared with higher-volume rural hospitals, which is a difference that persisted after confounder adjustment. Although most outcomes did not differ in nonrural hospitals, rates of prolonged LOS after chorioamnionitis and

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    Supported by grant number R40 MC 25694-01-00 from the Maternal and Child Health Research Program, Maternal and Child Health Bureau (Title V, Social Security Act), Health Resources and Services Administration, Department of Health and Human Services (J.M.S. and A.B.C.), and by the UCSF Women’s Reproductive Health Research Career Development Award, NIH, Eunice Kennedy Shriver National Institute of Child Health and Human Development (K12 HD001262, Y.W.C.).

    The content is solely the responsibility of the authors and does not necessarily represent the official views of National Institutes of Health or Health Resources and Services Administration.

    The authors report no conflict of interest.

    Cite this article as: Snowden JM, Cheng YW, Emeis CL, et al. The impact of hospital obstetric volume on maternal outcomes in term, non–low-birthweight pregnancies. Am J Obstet Gynecol 2015;212:380.e1-9.

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