Background incidence rates of adverse pregnancy outcomes in the Netherlands: Data of 2006-2018

Maarten M Immink, Sanne Koole, Mireille N Bekker, Floris Groenendaal, Jeanet M Kemmeren, Hester E de Melker, Nicoline A T van der Maas

Research output: Contribution to journalArticleAcademicpeer-review


OBJECTIVE: Maternal vaccination is an effective and safe intervention to protect newborns against infectious diseases shortly after birth. We assessed background rates of adverse pregnancy outcomes before the implementation of a maternal pertussis immunisation programme in the Netherlands, to put into perspective the safety concerns about such outcomes following immunisation.

STUDY DESIGN: In this retrospective cross-sectional study, annual numbers of pregnancy outcomes derived from the Dutch Perinatal Registry were used to calculate incidence rates per 10,000 in the 2006-2018 period. Births of ≥500 g birth weight and ≥24 + 0 w gestational age were included. Trends with moving-average-lines over the past 3 years were plotted, with 95 % confidence interval.

RESULTS: From 2006 through 2018, yearly numbers of pregnancies ranged between 158,868-175,710. Numbers of newborns ranged between 161,307-178,874, of whom 160,838-178,177 were live-born. Most outcomes were stable over time. Between 2006-2011, occurrence of labour induction increased by 68 %, and postpartum hemorrhage increased by 25 %. Both stabilised from 2011 onwards. Perinatal mortality up to day 7 or 28 postpartum decreased by 38 % and 37 %, respectively. Occurrence of low Apgar score among preterm infants born before 37 + 0 w gestational age and among term infants increased by 19 % and 27 %, respectively.

CONCLUSION: Our study on background incidences showed notable increases over time in occurrence of labour induction, postpartum hemorrhage and low Apgar score, while showing a considerable decrease in overall perinatal mortality. These findings should be considered when interpreting data on adverse events occurring since the maternal pertussis immunisation programme was implemented.

Original languageEnglish
Pages (from-to)274-280
Number of pages7
JournalEuropean Journal of Obstetrics, Gynecology and Reproductive Biology
Publication statusPublished - Jan 2021


  • preterm birth
  • vaccination
  • perinatal asphyxia
  • Incidence rates
  • Safety
  • Adverse pregnancy outcomes
  • Maternal pertussis vaccination


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