Text and Data Mining valid from 2018-12-01
Received: 6 August 2018
Accepted: 21 November 2018
First Online: 7 December 2018
Ethics approval and consent to participate
: The study protocol was approved by the Institutional Ethics Committee of St. Orsola-Malpighi Hospital, University of Bologna (reference number: 13/2016/O/Sper). Parents of all the participants gave informed written consent.
: Not applicable.
: The authors declare that they have no competing interests.
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