title: The association between serum β-hCG on day 24 of pregnancy and ongoing pregnancy in frozen embryo transfer cycles.
abstract: OBJECTIVE
  To determine the relationship between serum levels of the β-subunit of human chorionic gonadotropin (β-hCG) on day 24 of pregnancy during a frozen embryo transfer (FET) cycle and ongoing pregnancy.
  
  
  METHODS
  In a retrospective cohort study, data were reviewed from women aged 38years or younger who underwent a FET cycle at Nanfang Hospital, Guangzhou, China, from January 2013 to December 2014. Inclusion criteria were use of hormone-replacement therapy to achieve an endometrial thickness of 8mm or more, and at least two surviving embryos. Serum β-hCG on day 24 of pregnancy was assessed in relation to ongoing pregnancy at 12weeks.
  
  
  RESULTS
  Overall, 217 patients who underwent 248 FET cycles were included. The only measure that differed between cycles with (n=112) and without (n=136) ongoing pregnancy was β-hCG level on day 24 of pregnancy (73.0±65.8 vs 19.4±34.5mIU/mL; P<0.001). Classification tree analysis showed that women with day-24 β-hCG levels higher than 26.6mIU/mL had a 75.8% likelihood of ongoing pregnancy. In receiver operating characteristic curve analysis, the corresponding area under curve was 0.845 (95% confidence interval 0.795-0.895).
  
  
  CONCLUSIONS
  A maternal serum β-hCG level higher than 26.6mIU/mL was predictive of ongoing pregnancy at 12weeks.
authors.affiliation: Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.affiliation: Biostatistics Department, Yale University, New Haven, CT, USA.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, China.
authors.forename: Ping-Ping
authors.initials: PP
authors.lastname: Guo
authors.affiliation: Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, China.
authors.forename: De-Sheng
authors.initials: DS
authors.lastname: Ye
authors.affiliation: International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Xu
authors.affiliation: Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, China. Electronic address: chensl_92@163.com.
authors.forename: Shi-Ling
authors.initials: SL
authors.lastname: Chen
mesh_terms: D000328:Adult; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D015925:Cryopreservation; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000166:cytology*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First; D012372:ROC Curve; D055815:Young Adult
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human
keywords: Frozen embryo transfer; Ongoing pregnancy; Pregnancy outcome; β-Subunit of human chorionic gonadotropin (β-hCG)