Center;
of;
Clinical;
Reproductive;
Medicine,;
the;
First;
Affiliated;
Hospital;
of;
Nanjing;
Medical;
University,;
Nanjing;
210029,;
China;
Division;
of;
Endocrinology,;
Harbor-UCLA;
Medical;
Center,;
CA90502,;
USA;
Jiangsu;
Institute;
for;
Family;
Planning,;
Nanjing;
210029,;
China;