Funding for this research was provided by:
statutory funds from the Medical University of Bialystok (N/ST/ZB/17/001/2232)
Received: 8 December 2017
Accepted: 18 September 2018
First Online: 4 October 2018
Ethics approval and consent to participate
: The study protocol was approved by the Ethics Committee, Medical University of Białystok (R-I-002/345/2007), and a written informed consent had previously been obtained from each woman or from her family member(s).
: Not applicable.
: The authors declare that they have no competing interests.
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