title: Effect of semen quality on human sex ratio in in vitro fertilization and intracytoplasmic sperm injection: an analysis of 27,158 singleton infants born after fresh single-embryo transfer.
abstract: OBJECTIVE
  To evaluate the effect of semen quality on human sex ratio in in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI).
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  A total of 27,158 singleton infants born between 2007 and 2012 after fresh single-embryo transfer.
  
  
  METHODS
  None.
  
  
  METHODS
  Proportion of male infants among liveborn infants.
  
  
  RESULTS
  There were 14,996 infants born after IVF, 12,164 infants born after ICSI with ejaculated sperm, and 646 infants born after ICSI with nonejaculated sperm. The sex ratio of IVF was 53.1% (95% confidence interval [CI], 52.3-53.9); the sex ratio of ICSI with ejaculated and nonejaculated sperm demonstrated as statistically significant reduction (48.2%; 95% CI, 47.3-49.1 and 47.7%; 95% CI, 43.8-51.6, respectively). In IVF, lower sperm motility, including asthenozoospermia (sperm motility <40%), was associated with a statistically significantly lower sex ratio compared with normal sperm (51.0%; 95% CI, 48.6-53.3 vs. 53.4%; 95% CI, 52.5-54.3). In ICSI with ejaculated sperm, there was no association between sperm motility and sex ratio. Sperm concentration was not associated with sex ratio in both IVF and ICSI.
  
  
  CONCLUSIONS
  In IVF, lower sperm motility was associated with a statistically significant reduction in sex ratio; ICSI with either ejaculated or nonejaculated sperm was associated with a statistically significant reduction in sex ratio regardless of semen quality.
authors.affiliation: Division of Reproductive Medicine, Center of Maternal-Fetal, Neonatal and Reproductive Medicine, National Center for Child Health and Development, Tokyo, Japan.
authors.forename: Mikiko
authors.initials: M
authors.lastname: Arikawa
authors.affiliation: Division of Reproductive Medicine, Center of Maternal-Fetal, Neonatal and Reproductive Medicine, National Center for Child Health and Development, Tokyo, Japan; SORA no MORI Clinic, Okinawa, Japan. Electronic address: jwa-s@ncchd.go.jp.
authors.forename: Seung Chik
authors.initials: SC
authors.lastname: Jwa
authors.affiliation: Department of Obstetrics and Gynecology, School of Medicine, University of Tokushima, Tokushima, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Kuwahara
authors.affiliation: Department of Obstetrics and Gynecology, School of Medicine, University of Tokushima, Tokushima, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Irahara
authors.affiliation: Division of Reproductive Medicine, Center of Maternal-Fetal, Neonatal and Reproductive Medicine, National Center for Child Health and Development, Tokyo, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Saito
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods / Q000639:trends; D006801:Humans; D007231:Infant, Newborn; D007248:Infertility, Male / Q000175:diagnosis / Q000628:therapy*; D008297:Male; D011247:Pregnancy; D012189:Retrospective Studies; D012661:Semen / Q000502:physiology*; D055101:Semen Analysis / Q000379:methods / Q000639:trends*; D012744:Sex Ratio; D056826:Single Embryo Transfer / Q000379:methods / Q000639:trends*; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods / Q000639:trends*; D013081:Sperm Motility / Q000502:physiology
keywords: Artificial reproductive technology; nonejaculated sperm; secondary sex ratio; semen analysis