title: Apparent lack of seasonal variation in implantation rates after in-vitro fertilization.
abstract: It has been suggested that seasonal variation in endometrial receptivity may occur in women, which could affect the likely success of in-vitro fertilization (IVF) treatment. We therefore studied implantation rates (fetal sacs as a proportion of embryos transferred) as an indirect index of receptivity in a narrowly defined population of women under 40 years old with normal ovulatory cycles and normal uterus and men with normal sperm function. A total of 577 cycles of IVF treatment were undertaken using a standard protocol of pituitary desensitization and ovarian stimulation during the 3 years 1990-1992. Results were compared between calendar months and 3-month seasons. The overall implantation rate was 14.9% of embryos, and the clinical pregnancy rate was 30.3% of cycles reaching egg collection. There were no significant differences in the monthly rates of eggs collected, fertilization and cleavage, or embryos transferred. Implantation rates varied to a greater extent but analysis of variance showed no seasonal variation. These findings do not support a seasonal variation in ovarian responsiveness or endometrial receptivity when stimulated for IVF treatment, but larger studies are needed for firm conclusions to be drawn.
authors.affiliation: University of Bristol, Department of Obstetrics and Gynaecology, St Michael's Hospital, UK.
authors.forename: C
authors.initials: C
authors.lastname: Fleming
authors.forename: L
authors.initials: L
authors.lastname: Nice
authors.forename: A O
authors.initials: AO
authors.lastname: Hughes
authors.forename: M G
authors.initials: MG
authors.lastname: Hull
mesh_terms: D000328:Adult; D010064:Embryo Implantation / Q000502:physiology*; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D008297:Male; D011247:Pregnancy; D012621:Seasons