Intrinsic fertility of human oocytes

In a large natural cycle, single embryo transfer in vitro fertilization program, live baby rate per egg reveals the intrinsic fertility of the human oocyte without stimulation.

Volume 107, Issue 5, Pages 1232–1237


Sherman J. Silber, M.D., Keiichi Kato, M.D., Ph.D., Naoki Aoyama, M.Sc., Akiko Yabuuchi, Ph.D., Helen Skaletsky, Ph.D., Yuting Fan, M.D., Kazunori Shinohara, M.D., Noriyuki Yatabe, M.D., Ph.D., Tamotsu Kobayashi, M.D.


The intrinsic fertility per oocyte in natural cycle is far greater than reported in hyperstimulated cycles, varying robustly from 26% to 4% with age from <35 to 42 years. The curve is relatively flat until age 34, and then declines rapidly 10% per year thereafter.

Read the full text here.


Go to the profile of Demetri Smith
about 5 years ago
How did you determine 34 was the age in which the curve starts to rapidly decline?
Go to the profile of James Moruzzi
over 4 years ago

The Silber article with data from the Kato Clinic (Tokyo) is historic.  It documents the inherent fertility of individual oocytes from natural cycle for a spectrum of maternal ages.

There are a few technical details that may help me in duplicating these results.

- What suction pressure was used on the 21 G Kitazato aspiration needles?

- The clinic monitored cycles with daily ultrasounds, serum estradiol (E2), progesterone (P4) and luteinizing hormone (LH).   But it only recommends using follicular size > or = 18 mm, and E2 > or = 250 pg / ml.  Were P4 and LH non-predictive of egg maturity?  

- Follicular aspiration was scheduled 32 - 35 hours after buserelin inhalation, having met the 18 mm size and E2 criteria.  Was the buserelin given that evening?  Was urinary LH monitored between the blood draw and administration of buserelin?

- What percentage of these monitored cycles resulted in retrieval of a mature oocyte?   What percentage of oocytes were immature or post-mature (atretic)?