There were 6,190 singleton deliveries with type 2 or GDM out of 159,537 (3.9%) hospitalizations for any delivery in Maryland in our data set during the 6-year study period. We were able to link 5,507 (89%) of the 6,190 maternal files with an infant file. The 683 total unmatched files consisted of the following: (1) women admitted for postpartum care only after delivery outside of the hospital (12%), (2) stillbirths (10%), (3) diagnosis of spontaneous miscarriage or miscarriage with hemorrhage (25%), and (4) deliveries of infants weighing ≤500
g (50%). We did not include cases in which the infant birth weight was less than 500
g because it is difficult to distinguish live births from second-trimester miscarriages. Mothers in the unmatched group were slightly younger, more likely to be white, and less likely to have had a prior cesarean delivery compared to the 5,507 mothers who matched to an infant.
Characteristics of study sample
There were 21 community-based, non-teaching hospitals, six community teaching hospitals, and three academic medical centers providing obstetrical care during the study period. Sixty-eight percent of the deliveries occurred at community hospitals, 26% at community teaching hospitals, and 5.2% at academic medical centers. There was little variation in outcomes among hospitals within each setting or each tertile of volume. The study sample was comprised of 4,680 (85%) hospitalizations among women with GDM and 826 (15%) hospitalizations among women with type 2 diabetes. As shown in , deliveries at community teaching hospitals and academic medical centers were more likely to involve young, single, black, and Medicaid-eligible women compared to deliveries at community, non-teaching hospitals (all p
0.05). The rate of chronic hypertension, pre-eclampsia, intrapartum infection, and maternal obesity was similar across hospital settings. Thirteen percent of the infants at academic medical centers weighed less than 2,500
g. The percentage of infants weighing 4,000
g or more was similar across settings.
Relation of maternal characteristics with clinical outcomes
Because of the differences in case mix across hospital settings, we examined the association of patient characteristics with each outcome of interest (). Black race had a protective effect on episiotomy, but was associated with higher odds of cesarean delivery. Conversely, Asian race was associated with higher odds of episiotomy, but lesser odds of cesarean delivery. Black race (RC, 0.4; 95% CI: 0.3, 0.6) and Asian race (RC, 0.7; 95% CI: 0.4, 1.0) were associated with longer lengths of hospital stay, compared to white women. For each 1-year increase in age, there was a 1.03 times higher odds of cesarean delivery (adjusted OR [aOR], 1.03; 95% CI: 1.02, 1.1). Each 1-year increase in age was associated with a 10% reduction in the odds of episiotomy. Age had a borderline significant, protective effect on composite maternal morbidity (OR, 0.98; 95% CI: 0.94, 1.00). The diagnosis of pre-eclampsia was statistically significantly associated with higher odds of cesarean delivery. Perinatal infection was associated with an increased likelihood of cesarean delivery (OR, 1.6; 95% CI: 1.1, 2.4), but a 60% reduction in episiotomy (OR, 0.4; 95% CI: 0.2, 0.8). Cesarean delivery was the strongest predictor of hospital length of stay (RC, 1.6; 95% CI: 1.5, 1.8). Maternal obesity was positively associated with cesarean delivery and the composite variable for maternal morbidity, but these relationships did not reach statistical significance.
Effect of hospital setting on primary cesarean, episiotomy, and maternal morbidity
We compared the rate of primary cesarean delivery, episiotomy, and a composite variable for maternal morbidity across three hospital settings (). The rate of cesarean delivery was similar across settings, ranging between 34% at community, teaching hospitals to 37% at community, non-teaching hospitals. Eighteen percent of episiotomies occurred at community, non-teaching hospitals compared to 11% and 5% at community, teaching hospitals and academic centers, respectively. Thirteen percent of the deliveries at academic hospitals were complicated by maternal morbidity compared to 9% of the deliveries at community, non-teaching and teaching hospitals.
In bivariate analysis, we estimated unadjusted ORs to show the relation of hospital setting to each outcome of interest. The bivariate analysis () suggested that the likelihood of cesarean delivery did not vary significantly in community-teaching and academic centers compared to community, non-teaching hospitals. Bivariate analysis also suggested that community-teaching hospitals and academic medical centers are associated with a 40% and 70% reduction in episiotomy compared to community, non-teaching hospitals. After adjustment for hospital volume, deliveries at community-teaching hospitals and academic medical centers were still associated with lesser odds of episiotomy. Bivariate analysis also suggested a higher likelihood of maternal morbidity at academic centers (OR, 2.2; 95% CI: 1.2, 4.3) compared to community, non-teaching hospitals. Adjustment for volume did not attenuate this relationship (OR, 2.4; 95% CI: 1.3, 4.8).
In a final step in the analysis, we determined the independent effect of setting on each outcome. After adjustment for patient case mix, deliveries at academic medical centers were associated with a 70% reduction in episiotomy (OR, 0.3; 95% CI: 0.2, 0.5). Further adjustment for patient case mix attenuated the relation of academic centers with maternal morbidity (OR, 2.1; 95% CI: 1.0, 4.2), but the relationship had borderline statistical significance.
Effect of hospital setting on length of stay
Length of stay for community hospitals was significantly shorter compared to community-teaching hospitals and academic centers (2.8 days compared to 3.2 and 4.2 days, respectively). After adjustment for volume, average hospital length of stay at community-teaching hospitals and academic centers was significantly higher compared to community hospitals (). In the fully adjusted model, community teaching hospitals and academic centers were still significantly associated with higher average lengths of stay.
Association of Hospital Setting and Volume with Length of Stay in Women with Type 2 and Gestational Diabetes
Among type 2 diabetics, delivery at a community-teaching hospital or academic medical center was associated with a higher likelihood of primary cesarean delivery. Conversely, delivery at teaching hospitals had a borderline protective effect on cesarean delivery among gestational diabetics. Delivery at academic medical centers was protective against maternal morbidity among type 2 diabetics. Among gestational diabetics, there was a borderline-significant positive association between delivery at academic medical centers and the likelihood of maternal morbidity ().
Association of Hospital Setting with Primary Cesarean Delivery, Episiotomy, and Maternal Morbidity by Diabetes Category