科学家通过研究发现，妇女到30岁时就已经消耗约90%的“卵子库存”。尽管三四十岁的妇女仍能排卵，但是不仅其“卵子库存”已经所剩无几，而且卵子质量下降，不利于生出健康的婴儿。这一发现揭示了中年妇女年龄越大越难受孕的奥秘。
这一最新研究是由苏格兰圣安德鲁斯大学和爱丁堡大学科研人员完成的，发表在《公共科学图书馆·综合》（PLoS ONE）上。所谓“卵子库存”是指一名女性一生所能产生的潜在卵子总数量。研究显示，女性的“卵子库存”平均可达30万，但是“卵子库存”的减少速度大大超过先前估计。到30岁时，女性的“卵子库存”平均还剩12%，到40岁时，下降到3%。
为了进行这项研究，科研人员收集了325名英、美和一些欧洲国家妇女的信息。该研究的作者之一汉密斯-华莱士博士说：“研究表明，妇女通常高估了自己的受孕几率。”研究人员表示，一些妇女错误地认为由于她们还能产生卵子，就觉得自己的受孕能力还保持不变。该研究显示，事实上，妇女的受孕能力会迅速下降。女性“卵子库存”的个体差异巨大。一些女性的“卵子库存”数量超过200万，一些人只有不到3.5万。
华莱士博士称，该项研究成果有助于预测哪些妇女会过早停经，以及何时为卵巢癌患者冷冻卵子。该研究警告女性，不要拖到年龄很大才准备受孕。女性超过35岁，受孕能力将明显下降，不过下降速度也因个体差异而不同。一些医生建议，定期对女性受孕能力进行筛查，正如宫颈癌筛查一样。（生物谷Bioon.com）
生物谷推荐原始出处：
PLoS ONE 5(1): e8772. doi:10.1371/journal.pone.0008772
Human Ovarian Reserve from Conception to the Menopause
W. Hamish B. Wallace1*, Thomas W. Kelsey2
1 Department of Reproductive and Developmental Sciences, Division of Child Life and Health, University of Edinburgh, Edinburgh, United Kingdom, 2 School of Computer Science, University of St Andrews, St Andrews, United Kingdom
The human ovary contains a fixed number of non-growing follicles (NGFs) established before birth that decline with increasing age culminating in the menopause at 50–51 years. The objective of this study is to model the age-related population of NGFs in the human ovary from conception to menopause. Data were taken from eight separate quantitative histological studies (n = 325) in which NGF populations at known ages from seven weeks post conception to 51 years (median 32 years) were calculated. The data set was fitted to 20 peak function models, with the results ranked by obtained correlation coefficient. The highest ranked model was chosen. Our model matches the log-adjusted NGF population from conception to menopause to a five-parameter asymmetric double Gaussian cumulative (ADC) curve ( r 2= 0.81). When restricted to ages up to 25 years, the ADC curve has r 2= 0.95. We estimate that for 95% of women by the age of 30 years only 12% of their maximum pre-birth NGF population is present and by the age of 40 years only 3% remains. Furthermore, we found that the rate of NGF recruitment towards maturation for most women increases from birth until approximately age 14 years then decreases towards the menopause. To our knowledge, this is the first model of ovarian reserve from conception to menopause. This model allows us to estimate the number of NGFs present in the ovary at any given age, suggests that 81% of the variance in NGF populations is due to age alone, and shows for the first time, to our knowledge, that the rate of NGF recruitment increases from birth to age 14 years then declines with age until menopause. An increased understanding of the dynamics of human ovarian reserve will provide a more scientific basis for fertility counselling for both healthy women and those who have survived gonadotoxic cancer treatments.
