title: Seasonal variability in the fertilization rate of women undergoing assisted reproduction treatments.
abstract: The objective of this study was to evaluate whether seasonality affects human-assisted reproduction treatment outcomes. For this, 1932 patients undergoing intracytoplasmic sperm injection (ICSI) were assigned to a season group according to the day of oocyte retrieval: winter (n = 435), spring (n = 444), summer (n = 469) or autumn (n = 584). Analysis of variance was used to compare the ICSI outcomes. The fertilization rate was increased during the spring (winter: 67.9%, spring: 73.5%, summer: 68.7% and autumn: 69.0%; p < 0.01). In fact, a nearly 50% increase in the fertilization rate during the spring was observed (odds ratio 1.45, confidence interval 1.20-1.75; p < 0.01). The oestradiol concentration per number of oocytes was significantly higher during the spring (winter: 235.8 pg/mL, spring: 282.1 pg/mL, summer: 226.1 pg/mL and autumn: 228.7 pg/mL; p = 0.030). This study demonstrates a seasonal variability in fertilization after ICSI, where fertilization is higher during the spring than at any other time.
authors.affiliation: Fertility-Assisted Fertilization Centre, Brigadeiro Luis Antônio, São Paulo, Brazil.
authors.forename: Daniela Paes De Almeida Ferreira
authors.initials: DP
authors.lastname: Braga
authors.forename: Amanda
authors.initials: A
authors.lastname: Setti
authors.forename: Rita de Cássia Sávio
authors.initials: Rde C
authors.lastname: Figueira
authors.forename: Assumpto
authors.initials: A
authors.lastname: Iaconelli
authors.forename: Edson
authors.initials: E
authors.lastname: Borges
mesh_terms: D000704:Analysis of Variance; D001938:Brazil; D015331:Cohort Studies; D004477:Ectogenesis; D004624:Embryo Transfer; D004958:Estradiol / Q000097:blood; D005260:Female; D006801:Humans; D007246:Infertility / Q000097:blood / Q000628:therapy*; D007247:Infertility, Female / Q000097:blood / Q000628:therapy; D008297:Male; D010062:Ovulation Induction; D017440:Photoperiod; D011247:Pregnancy; D018873:Pregnancy Rate; D034121:Reproductive Health Services; D027724:Reproductive Techniques, Assisted; D012189:Retrospective Studies; D012621:Seasons; D020554:Sperm Injections, Intracytoplasmic
chemical_list: D004958:Estradiol