title: Low body mass index compromises live birth rate in fresh transfer in vitro fertilization cycles: a retrospective study in a Chinese population.
abstract: To evaluate the effects of low body mass index (BMI) on in vitro fertilization (IVF) outcomes in fresh transfer cycles.
  
  
  
  Retrospective cohort study.
  
  
  
  University-affiliated hospital.
  
  
  
  A total of 4,798 cycles with conventional stimulation and fresh transfer in a single IVF center during the period 2013-2014. Low BMI (<18.5 kg/m2) was defined according to World Health Organization guidelines, and cycles within a normal weight range (18.5-24.9 kg/m2) were used as reference.
  
  
  
  None.
  
  
  
  Live birth rate per fresh embryo transfer.
  
  
  
  Low BMI was associated with reduced live birth rates and increased miscarriage rates compared with normal weight, controlling for important covariates known to influence IVF outcomes. Patient age was the most potent confounder, causing a 10.5% reduction in the odds ratio (OR) for live birth between the groups compared. When an interaction term (age × BMI) was introduced, the OR for live birth was reduced in cycles of those aged ≥35 years compared with cycles of those aged 28-34 years, whereas the change in OR between cycles in those aged <28 and cycles in those aged 28-34 years was insignificant.
  
  
  
  Low BMI is associated with negative outcomes in fresh transfer cycles, especially for women of advanced age.
authors.affiliation: Reproductive Medicine Center, Affiliated Chenggong Hospital of Xiamen University, Fujian, People's Republic of China.
authors.forename: Jiali
authors.initials: J
authors.lastname: Cai
authors.affiliation: Reproductive Medicine Center, Affiliated Chenggong Hospital of Xiamen University, Fujian, People's Republic of China.
authors.forename: Lanlan
authors.initials: L
authors.lastname: Liu
authors.affiliation: Reproductive Medicine Center, Affiliated Chenggong Hospital of Xiamen University, Fujian, People's Republic of China.
authors.forename: Junwen
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Reproductive Medicine Center, Affiliated Chenggong Hospital of Xiamen University, Fujian, People's Republic of China.
authors.forename: Huiling
authors.initials: H
authors.lastname: Qiu
authors.affiliation: Reproductive Medicine Center, Affiliated Chenggong Hospital of Xiamen University, Fujian, People's Republic of China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Reproductive Medicine Center, Affiliated Chenggong Hospital of Xiamen University, Fujian, People's Republic of China.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: Reproductive Medicine Center, Affiliated Chenggong Hospital of Xiamen University, Fujian, People's Republic of China.
authors.forename: Aiguo
authors.initials: A
authors.lastname: Sha
authors.affiliation: Reproductive Medicine Center, Affiliated Chenggong Hospital of Xiamen University, Fujian, People's Republic of China. Electronic address: rjz174@126.com.
authors.forename: Jianzhi
authors.initials: J
authors.lastname: Ren
mesh_terms: D000022:Abortion, Spontaneous / Q000453:epidemiology; D000328:Adult; D044466:Asian People; D015992:Body Mass Index; D016009:Chi-Square Distribution; D002681:China / Q000453:epidemiology; D010064:Embryo Implantation; D004624:Embryo Transfer / Q000009:adverse effects; D005260:Female; D005298:Fertility; D005307:Fertilization in Vitro / Q000009:adverse effects; D006785:Hospitals, University; D006801:Humans; D007246:Infertility / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology / Q000628:therapy*; D050498:Live Birth; D016015:Logistic Models; D008423:Maternal Age; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D020554:Sperm Injections, Intracytoplasmic; D013851:Thinness / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
keywords: In vitro fertilization; body mass index; fresh embryo transfer; live birth; underweight