James W H
Ann Hum Biol. 1979 Sep-Oct;6(5):481-3. doi: 10.1080/03014467900003871.
The dizygotic (DZ) twinning rate declines after about maternal age 38 in Caucasian populations. Bulmer (1970) offered the explanation that waning ovarian function causes a decline in rates of double ovulation in originally twin-prone women. The present note suggests that some small part of the decline is caused by the earlier cessation of ovulation altogether in these women (presumably also as a result of waning ovarian function).
在白种人群中，双卵双胎（DZ）的发生率在母亲年龄约38岁后会下降。布尔默（1970年）给出的解释是，卵巢功能的衰退导致原本易怀双胎的女性双排卵发生率下降。本报告表明，这种下降的一小部分原因是这些女性排卵完全停止的时间提前（大概也是卵巢功能衰退的结果）。
