Early and late preterm delivery rates - a comparison of differing tocolytic policies in a single urban population

Preterm delivery results in neonatal morbidity and mortality. We set out to estimate the difference in rates of preterm delivery in two institutions, serving a single population, with differing policies regarding use of tocolytic drugs for the prevention of preterm delivery.

A retrospective study comparing preterm delivery rates between 2002 and 2007 in two large tertiary hospitals serving a single urban population with similar risk factor profile located less than 2 miles from each other. During the study period Hospital A routinely used tocolytic therapy, Hospital B operates a policy of never using any tocolytic drugs. Rates of delivery prior to 26, 30, 34 and 37 weeks were compared for each hospital.

During the study period there were 90,843 deliveries between the two hospitals. The overall rates of preterm delivery at less than 37 weeks gestation were comparable with 6.62% (2794/42,232) in Hospital A and 6.15% (2989/48,611) in Hospital B (p = 0.99). There was no significant difference in the numbers delivering at less than 34 weeks, 995/42,232 (2.36%) versus 1134/48,611 (2.33%), p = 0.59, less than 30 weeks, 403/42,232 (0.95%) versus 429/48,611 (0.88%), p = 0.87 or prior to 26 weeks, 126/42,232 (0.29%) versus 121/48,611 (0.25%), p= 0.08.

In this large population routine use of tocolytic drugs in the treatment of threatened preterm labor does not alter rates of early or late preterm delivery. While this study is limited by its retrospective nature, it calls into question the practice of tocolysis.