Infertility increases with age. The effect of the female's age is more dramatic and earlier than that of the male, but an age effect is seen with advancing male age also.
Fertile peaks when the woman is in her late teens and early twenties. It begins to decline at age thirty and drops more rapidly after age 35 years (8). It plummets after age 40 and pregnancy after age 45 is rare (7,9). This phenomenon is also reflected in the live birth rate and has been remarkably stable over time and geography as seen in figure 1. Miscarriages are also more frequent as maternal age rises (10). Although one may suggest that this is because of the well-known increase in aneuploid conceptions with maternal age (11), euploid pregnancies are also lost with higher frequency as the mother ages. Large scale studies of women older than 44 conceived using either ovulation induction and intrauterine insemination or in vitro fertilization reveal a 75% spontaneous abortion rate after the age of 44 years. (11.1)
The effect of maternal age on fertility is theoretically an effect of a larger proportion of abnormal embryos with increasing maternal age. Data from in vitro fertilization in which normal appearing embryos were examined with fluorescent in situ hybridization (FISH), revealed 39% abnormal embryos from women who are greater or equal to 40 years of age compared to 5% from women who are 20 to 34 years of age (12).
Frequently unaddressed, is the effect of the male's age. Sperm count does drop with age, although the individual variation is wide as is the male's sexual function. The decreasing fertility of the male roughly lags behind that of the female by 10 years. Significant infertility is seen after age 55 years, although these data are difficult to come by, because of the more impressive effect of maternal age. In order to gain firm figures, men at various ages older than 45, married to women younger than 30 would have to be surveyed for intercourse frequency and conception. The only data available are those from the Mormon genealogy registers (see Figure 2)(13).
Thus, men older than 55 married to women older than 35 may have a synergistic age effect on their fertility, but one which is difficult to quantify.