Decreasing trend in preterm birth and perinatal mortality, do disparities also decline?

Abstract

Background: In the Netherlands, several initiatives started after the publication of the PERISTAT findings that showed the perinatal mortality risk was higher than in other European countries. The objective of this study is 1) to report recent trends in perinatal mortality and in intermediate risk groups (preterm birth, congenital anomalies and small for gestational age (SGA)), 2) describing perinatal mortality risk among children born preterm, with congenital anomalies or SGA, and born in maternal high risk groups (parity, age, ethnicity and socio-economic status (SES)). Methods: A nationwide cohort study in the Netherlands among 996,423 singleton births in 2010-2015 with a gestational age between 24.0 and 42.6 weeks. Trend tests, univariate and multivariable logistic regression analyses were used. We did separate analyses for gestational age subgroups and line of care. Results: The perinatal mortality rate was 5.0 per 1000 and it decreased significantly from 5.6 in 2010 to 4.6 per 1000 in 2015. Preterm birth significantly declined (6.1% in 2010 to 5.6% in 2015). Analysis by gestational age groups showed that the largest decline in perinatal mortality of 32% was seen at 24-27 weeks of gestation where the risk declined from 497 to 339 per 1000. At term, the decline was 23% from 2.2 to 1.7 per 1000. The smallest decline was 3% between 32 and 36 weeks. In children with preterm birth, congenital anomalies or SGA, the perinatal mortality risk significantly declined. Main risk factors for perinatal mortality were African ethnicity (adjusted odds ratio (aOR) 2.1 95%CI [1.9-2.4]), maternal age ≥ 40 years (aOR1.9 95%CI [1.7-2.2]) and parity 2+ (aOR 1.4 95%CI [1.3-1.5]). Among the (post)term born neonates, there was no significant decline in perinatal mortality in women with low age, low or high SES, non-Western ethnicity and among women who started or delivered under primary care. Conclusions: There is a decline in preterm birth and in perinatal mortality between 2010 and 2015. The decline in perinatal mortality is both in stillbirths and in neonatal mortality, most prominently among 24-27 weeks and among (post)term births. A possible future target could be deliveries among 32-36 weeks, women with high maternal age or non-Western ethnicity.