Received: 29 August 2019
Accepted: 5 January 2020
First Online: 10 February 2020
Ethics approval and consent to participate
: The study protocol was approved by Menoufia Faculty of Medicine Committee for Medical Research Ethics. This committee does not grant reference numbers for the approved researches. A written informed consent was obtained from the parents.
: Not applicable
: The authors declare that they have no competing interests.