Menstrual cycle length is an age-independent marker of female fertility: results from 6271 treatment cycles of in vitro fertilization

Objective: To investigate whether menstrual cycle length correlates with success rates at IVF/intracytoplasmic sperm injection (ICSI) and could be used as a marker of ovarian reserve. Design: Prospective observational study. Setting: Private infertility centre. Patient(s): A total of 6271 IVF/ICSI treatment cycles. Intervention(s): Self-reported mean number of menstrual days during the last year was recorded before initiation of IVF/ICSI treatment. Main Outcome Measure(s): Relations between menstrual cycle length and pregnancy and delivery rates. Result(s): Increasing age was associated with a subtle shortening of mean menstrual cycle length. Menstrual cycle length correlated linearly with pregnancy and delivery rates, even after age adjustment. The chance of delivery after IVF/ICSI was almost doubled for women with a menstrual cycle length >34 days compared with women with a menstrual cycle length <26 days. Menstrual cycle length was also significantly associated with ovarian response to FSH/hMG stimulation and embryo quality. Conclusion(s): Mean menstrual cycle length is highly related to success rates in assisted reproduction, independently of age. A precise menstrual cycle history could be used as a simple marker of ovarian reserve. (Fertil Steril(R) 2008;90:1656-61. (C)2008 by American Society for Reproductive Medicine.)