Impact of oestradiol and inhibin A concentrations on pregnancy rate in in-vitro oocyte maturation.

The purpose of the present study was to analyse the results of maturation of oocytes obtained in unstimulated normal women after a leading follicle of 10 mm diameter and an endometrium of at least 5 mm thickness were observed at ultrasound. The serum concentrations of oestradiol and inhibin A were analysed from day 3 to the day of aspiration and retrospectively evaluated. A total of 75 normal regular cycling women referred for IVF/intracytoplasmic sperm injection (ICSI) because of male factor and/or tubal disease was included (n = 87 consecutive cycles). The oocytes were aspirated transvaginally and matured for 28-36 h. ICSI was performed on all metaphase II oocytes and they were cultured to day 2 or 3 after insemination, at which time suitable embryos (maximum two) were replaced into the women. Eleven singleton pregnancies with a live fetus were obtained after transfer in 63 cycles (pregnancy rate of 13% per aspiration and 17% per transfer). Nine healthy children have been born and the remaining two pregnancies miscarried in the eighth to ninth gestational week. The serum concentrations of oestradiol on day 3 and on the day of aspiration were available in 85 cycles, and in 57 of these an increase of 100% was detected on the day of aspiration. Significantly more pregnancies were observed in these cycles compared with cycles without an increase in the concentration of oestradiol (19 versus 0% per aspiration, 24 versus 0% per transfer, P < 0.02). Further improvement in pregnancy rate was obtained if aspiration was performed after increase in inhibin A concentration (24 versus 0% per aspiration and 33 versus 0% per transfer, P < 0.02) (n = 83 cycles, where inhibin concentrations were available, and n = 42 cycles, where an increase of 80% was detected on the day of aspiration compared with day 3). Timing of aspiration may improve the developmental potential of immature oocytes.