Strengths and limitations and future research
The main strength of our study is that we studied a large cohort of more than one million infants using a national registry that covers nearly all births (98%) in the Netherlands. An important limitation, besides the lack of the long-term outcome, is that data about therapeutic hypothermia were missing. As therapeutic hypothermia was not registered yet as item in the national registry, we could not study trends in the main treatment for severe birth asphyxia. We want to collect these data for future studies.
In this study we did not focus on higher 5-minute Apgar scores of 7, 8 and 9, but there is growing evidence that children with these Apgar scores are also more likely to have developmental vulnerability at population level, compared to children with Apgar score of 10.(28) It would be interesting to analyse trends in these higher Apgar scores in future studies.