title: Effect of maternal height and weight on risk for preterm singleton and twin births resulting from IVF in the United States, 2008-2010.
abstract: OBJECTIVE
  To analyze the effects of preconception maternal height and weight on the risk of preterm singleton and twin births resulting from in vitro fertilization (IVF).
  
  
  METHODS
  We performed a retrospective cohort analysis of the incidence of very early preterm birth (VEPTB), early preterm birth (EPTB), and preterm birth (PTB), before 28, 32, and 37 completed weeks, respectively, in 60,232 singleton and 24,111 twin live births using 2008-2010 live birth outcome data from the Society for Reproductive Technology Clinic Outcome Reporting System.
  
  
  RESULTS
  Maternal obesity is associated with significantly increased risk of VEPTB, EPTB, and PTB in pregnancies conceived by IVF. For morbidly obese women (body mass index ≥35) with singletons, rates of VEPTB, EPTB, and PTB were 1.7%, 3.6%, and 16.4%, with adjusted risk ratios (aRRs) and 95% confidence levels (CIs) of 2.6 (1.8-3.6), 2.2 (1.8-2.6), and 1.5 (1.4-1.7) using corresponding rates for normal body mass index (95% CI, 18.6-24.9) as referent. For morbidly obese women with twins, rate of VEPTB and EPTB were 6.5% and 12.5%, with aRRs and 95% CIs of 2.4 (1.8-3.0) and 1.5 (1.3-1.8). For singletons, the rate of PTB for short stature women (<150 cm) was 14.2%, as compared with 11.8% in those women with height ranging between 160-167 cm (referent), with aRRs and 95% CIs of 1.2 (1.0-1.4).
  
  
  CONCLUSIONS
  Preconception maternal obesity and short stature are associated with significantly increased risk of VEPTB and early preterm singleton and twin births in pregnancies resulting from IVF.
authors.affiliation: Section of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Louisiana State University School of Medicine, New Orleans, and The Fertility Institute of New Orleans, Mandeville, LA.
authors.forename: Richard P
authors.initials: RP
authors.lastname: Dickey
authors.forename: Xu
authors.initials: X
authors.lastname: Xiong
authors.forename: Yiqiong
authors.initials: Y
authors.lastname: Xie
authors.forename: Rebekah E
authors.initials: RE
authors.lastname: Gee
authors.forename: Gabriella
authors.initials: G
authors.lastname: Pridjian
mesh_terms: D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D015331:Cohort Studies; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D009765:Obesity / Q000453:epidemiology*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology; D059285:Pregnancy, Twin / Q000706:statistics & numerical data; D047928:Premature Birth / Q000453:epidemiology*; D012189:Retrospective Studies; D012306:Risk; D014481:United States / Q000453:epidemiology
keywords: IVF; early preterm birth; preconception maternal BMI; preconception maternal height; preconception maternal weight; preterm birth; singleton; twin; very early preterm birth