Funding for this research was provided by:
Received: 11 June 2020
Accepted: 18 September 2020
First Online: 1 October 2020
Ethics approval and consent to participate
: The study was approved by The Regional Ethics committee in Stockholm, Sweden (Dnr 2015/2105–31/1), 13 January 2016. The women got informed that it was voluntary for them to accept information and practice the method. At registration in maternity clinic, the women gave written consent that their data in The Swedish Pregnancy Register can be used in research. Regarding consent to participate in research for underage study participants, from the age of 15, the authors refer to Swedish legislation (Law 2003: 460).
: Not applicable.
: The authors declare that they have no competing interests and there are not any financial competing interests.