2Kaur G,Srivastav J,Kaur A,et al.Maternal serum second trimester screening for chromosomal disorders and neural tube defects in a government hospital of North India[J].Prenat Diagn,2012,32(12):1192-1196.
3Chedane C,Puissant H,Weil D,et al.Association between altered placental human chorionic gonadotrophin(h CG)production and the occurrence of cryptorchidism:a retrospective study[J].BMC Pediatr,2014,14:191.