Received: 16 January 2019
Accepted: 12 July 2019
First Online: 25 July 2019
Ethics approval and consent to participate
: The study has ethical approval according to the ethics review board of Zurich (reference number KEK-ZH 2015–0011, date of approval: 4.9.2015). This approval and the consent to participate were obtained for the previous study (the prospective cohort study investigating risk factors for PPH). In accordance with our ethics board the ethics approval of the mother study can be applied to this secondary analysis.
: Not applicable.
: The authors declare that they have no competing interests.