Effects of nationwide adjustment of tocolysis protocol in the Netherlands on neonatal outcomes in women with threatened preterm birth and delivery at 30-32 weeks of gestation: A cohort study

Objective: In 2019 the Dutch national prevention of preterm birth (PTB) protocol was adjusted to withhold tocolysis for threatened PTB above 30 weeks of gestation due to insufficient evidence regarding its effectiveness on improving perinatal outcomes. The aim of this study is to evaluate neonatal outcomes of children born in the Netherlands between 30 and 32 weeks of gestation before and after the national protocol change.

Study design: We performed a nationwide retrospective cohort study comparing outcomes of births in the years 2018 (tocolysis) and 2020 (no tocolysis). Tocolytic therapy consisted of either nifedipine or atosiban. Data were extracted from the national Perinatal Registry (PERINED). Women with a spontaneous PTB from 30 + 0 to 31 + 6 weeks of gestation were included. The primary outcome was a composite of mortality, severe intraventricular hemorrhage, severe necrotizing enterocolitis, cystic periventricular leukomalacia, and retinopathy of prematurity needing therapy. Secondary outcomes included additional neonatal outcomes. The odds ratio (OR) with corresponding 95 % confidence interval (CI) was calculated by logistic regression analysis for the year 2020 compared with 2018.

Results: Composite neonatal outcome did not differ between 2018 compared to 2020 (8.4 % (18/215) vs 8.2 % (25/306), OR 0.95; 95 % CI 0.51-1.77). No difference in composite neonatal outcome was found when analyzing groups as singletons (7.1 % vs 9.3 %, OR 1.35; 95 % CI 0.64-2.87), and multiples (13.3 % vs 5.9 %, OR 0.41; 95 % CI 0.13-1.26).

Conclusion: There was no significant difference in composite neonatal outcome in pregnancies resulting in spontaneous PTB between 30 and 32 weeks of gestation in 2018 (with tocolysis) compared to 2020 (no tocolysis). These results support the protocol adjustment to withhold tocolytic treatment in women with threatened PTB above 30 weeks of gestation.