Received: 18 February 2019
Accepted: 15 November 2019
First Online: 29 November 2019
Ethics approval and consent to participate
: The study was approved by the Regional Research Ethics Committee in Gothenburg, Sweden (ref. no. 696–13), and the World Medical Association Declaration of Helsinki was adhered to. All participants gave their written informed consent. Basic information about the infants was retrieved from medical records (i. e. gestational age, sex and length of hospital stay).
: Not applicable.
: The authors declare that they have no competing interests.