Received: 9 January 2019
Accepted: 11 July 2019
First Online: 18 July 2019
Ethics approval and consent to participate
: The study received ethical clearance from the department of Obstetrics and Gynecology, Faculty of Medicine, University of Khartoum, Sudan. The files were reviewed retrospectively and anonymously. Therefore no consent was needed.
: Not applicable.
: The authors declare that they have no competing interests.