TY  - JOUR
A1  - Astolfi, P.
A1  - Zonta, L.A.
T1  - Risks of preterm delivery and association with maternal age, birth order, and fetal gender
Y1  - 1999
DO  - 10.1093/humrep/14.11.2891
VL  - 14
IS  - 11

ER  -