1 Zhang P.What can be learned from the Chinese experience in response to infertility.Eur J Contracept Reprod Health Care,2020,25(4):311-313. 2 Wu JQ,Yu CN,Li YY.Effects of family planning factors on the awareness of sexual and reproductive healthcare rights among married women of reproductive age in China:a cross sectional study.BMJ open,2017,p.e17621. 3 陈子江. “二孩”生育政策后再生育的临床思考.山东大学学报(医学版),2017,55(01):1-4. 4 Wahlberg A.The birth and routinization of IVF in China.Reprod Biomed Soc Online.2016,2:97-107. 5 Chen SM,Zhang Y,Wang YB.Individual differences in relative fertility costs and fertility benefits and their effects on fertility desire for a second child in China:a latent profile analysis.Reprod Health.2019,16(1):110. 6 张晓青,黄彩虹,张强,等.“单独二孩”与“全面二孩”政策家庭生育意愿比较及启示.人口研究,2016,40(01):87-97. 6 顾宝昌. 生育意愿、生育行为和生育水平.人口研究,2011,35(02):43-59. 7 Yi Z,Hesketh T.The effects of China's universal two-child policy.Lancet,2016,388(10054):1930-1938. 8 Gupta MD,Chung W,Li SZ.Evidence for an incipient decline in numbers of missing girls in China and India.POPUL DEV REV,2009,35(2):401-416. 9 Wang T,Wang C,Zhou Y,et al.Fertility intentions for a second child among urban working women with one child in Hunan Province,China:a cross-sectional study.Public Health,2019,173:21-28. 10 汪奕名,周学馨,唐贵忠,等.“全面两孩”政策背景下重庆市育龄妇女二孩生育意愿及影响因素研究.现代预防医学,2017,44(23):4271-4275. 11 马赫,尹文强,王安琪,等.全面二孩政策下山东省育龄女性二孩生育意愿及影响因素分析.卫生软科学,2019,33(06):16-20. 12 Qian Y,Liu XY,Fang B,et al.Investigating fertility intentions for a second child in contemporary China based on user-generated content.Int J Environ Res Public Health,2020,17(11):3905. 13 林永玲,梁瑞琼,谢宁,等.全面二孩政策下广东省居民生育意愿调查.卫生软科学,2016,30(12):59-65. 14 Rosa LP,Lomelino LA,Pinheiro MP,et al.Advanced maternal age:Adverse outcomes of pregnancy,a meta-analysis.Acta Med Port,2019,32(3):219-226. 15 Santana DS,Silveira C,Costa ML,et al.Perinatal outcomes in twin pregnancies complicated by maternal morbidity:evidence from the WHO Multicountry Survey on Maternal and Newborn Health.BMC pregnancy childbirth,2018,18(1):449. 16 Habbema JD,Eijkemans MJ,Leridon H,et al.Realizing a desired family size:when should couples start? Hum Reprod.2015,30(9):2215-2221. 17 Capelouto SM,Archer SR,Morris JR,et al.Sex selection for non-medical indications:a survey of current pre-implantation genetic screening practices among U.S.ART clinics.J Assist Reprod Gen,2018,35(3):409-416. 18 Fritz R,Jindal S.Reproductive aging and elective fertility preservation.[J] Ovarian Res.2018,11(1):66. 19 Rienzi L,Gracia C,Maggiulli R,et al.Oocyte,embryo and blastocyst cryopreservation in ART:systematic review and meta-analysis comparing slow-freezing versus vitrification to produce evidence for the development of global guidance.Hum Reprod Update,2017,23(2):139-155. 20 Rivas LEC,Lucci CM,Amorim CA.Cryopreservation of human ovarian tissue:A review.Transfus Med Hemother,2019,46(3):173-181. 21 Chen T,Li B,Shi H,et al.Reproductive outcomes of single embryo transfer in women with previous cesarean section.Reprod Sci,2021,28(4):1049-1059. 22 Hellerstein S,Feldman S,Duan T,et al.China's 50% caesarean delivery rate:is it too high? BJOG,2015,122(2):160-164. 23 Sullivan-Pyke CS,Senapati S,Mainigi MA,et al.In Vitro fertilization and adverse obstetric and perinatal outcomes.Semin Perinatol,2017,41(6):345-353.