Association between annual twin delivery volume and severe postpartum hemorrhage in twin pregnancies.

OBJECTIVE

To assess the association between the risk of severe postpartum hemorrhage (PPH) and the annual twin delivery volume of maternity units.

METHODS

JUmeaux MODe d'Accouchement (JUMODA) was a national observational prospective population-based cohort of twin deliveries in 176 French maternity units performing more than 1500 annual deliveries. Our analysis included 7348 women who delivered after 32 weeks' gestation. The primary outcome was severe PPH. The exposure of interest was the volume of annual twin deliveries defined as the number of annual twin deliveries per center in the study population, divided in three terciles. We compared the risk of severe PPH in maternity units with a low or moderate annual twin delivery volume to high volume group and used a propensity score weighting approach to control for confounding.

RESULTS

Severe PPH occurred in 3.5% of women in the low-volume group (4-24 twin deliveries per year), 4.2% in the moderate-volume group (25-47), and 5.0% in the high-volume group (48-184) (P = 0.081). After propensity score weighting, as compared to women delivering in the high-volume group, the risk of severe PPH did not significantly differ for those in the low-volume group (OR 0.73, 95% CI: 0.49-1.07) or in the moderate-volume group (OR 0.84, 95% CI: 0.63-1.12). Absolute risk difference was 1.64% (95% CI: -3.04-0.24) for the low- between high-volume group and -0.72% (95% CI: -3.04-0.24) for the moderate- versus high-volume group. Results were similar after stratifying by mode of delivery and when only very severe PPH was considered.

CONCLUSION

Severe PPH rates in twin pregnancies do not differ by the annual twin delivery volume of the maternity hospital, which questions the relevance of using this characteristic to limit where women can give birth, provided that a skilled obstetric and onsite anesthesiology team are available. Caution is therefore warranted when generalizing these results to other healthcare settings, particularly in low- and middle-income countries, where health system organization, resource availability, may substantially differ.