Age and Infertility

Abstract

Measuring the effect of age on fertility is difficult because so many people use artificial methods to control fertility. Data from Western communities employing no artificial methods, such as the Hutterites of North America, show a gradual decline in fertility with age, which becomes steeper after 40 and approaches zero by 49.12 Increasing age of the man, reduced coital frequency,3 and increasing duration of marriage4 may all influence this decline, but data from a community where late marriage was common showed a similar pattern: 16% of women married between 30 and 34 remained childless, as did 31% of those marrying between 35 and 39 and 69% of those marrying over 40.3 These studies may not be relevant to women in contemporary society, where contraceptive practices allow early sexual activity with'the option of delaying pregnancy for up to 20 years. During this time pelvic infection may reduce the chances of a future planned pregnancy.56 Tubal disease is not, however, an important cause of infertility,78 and there is no evidence that the prolonged use of oral contraception is detrimental to fertility.9 Indeed, it may protect against certain disorders associated with rising age and nulliparity, such as uterine fibroids."0 Of more concern is the idea that fecundity is declining in both men and women because of adverse environmental factors.6' These would predominantly affect older women because of the prolonged exposure of their oocytes to such influences, but deteriorations in semen characteristics have also been reported. 12 The study by Johnson et al is reassuring because it does not show a rise in involuntary infertility with age, although no information is available about women who may deliberately defer child-bearing until after 35 (28 March, p 804). Any adverse effect of aging would increase the number of couples presenting with "unexplained" infertility, and analysis of conception rates among couples thus classified confirms that the prognosis is inversely related to the age of the women at presentation.913 There is no evidence, however, that couples with unexplained infertility are any older at presentation than those in other diagnostic groups,'4 and age did not significantly affect prognosis for couples in these other categories.'516 In such studies it is difficult to control for an effect of aging in the man. Semen collected from men of proved fertility undergoing routine analysis before vasectomy or for screening as potential donors in artificial insemination by (© BRITISH MEDICAL JOURNAL 1987. All reproduction rights reserved. donor programmes shows an age related decline in sperm motility and morphological characteristics.'7 One study controlled for male factors and coital frequency by looking at women with azoospermic husbands who were artificially inseminated': a cumulative conception rate of 73% after 12 months in women aged 30 and under fell to 63% in those between 31 and 35 and to 54% in those over 35. Though supporting a decline in fecundity with age, these figures do not allow for the incre...

Childlessness in Europe: Reconstructing Long-Term Trends Among Women Born in 1900–1972

“…The mean age at first birth among women has exceeded 30 in Italy, Spain, and Switzerland; and is approaching this boundary in many other European countries. The share of women who are still childless at ages 35-40, when infertility becomes an important limiting factor (Menken et al 1986), has risen rapidly in much of Europe. For instance, in Spain 35 % of women aged 35 were childless in 2011, up from 16 % in 1991 (computations are based on census data).…”

What do men want? Re-examining whether men benefit from higher fertility than is optimal for women

“…On the other hand, the mother's residual reproductive value (i.e. how many future children she can produce times their quality), R, decreases the longer she waits because of senescence [50]. This means that a female's fitness, W f (equation (2.1)) will be equal to the sum of the value of her current child and her residual reproduction given that she survives to be able to reproduce.…”

Paternal age and reproduction

“…Reduced fertility in aging women is primarily due to 'ovarian aging' with reduced quality and reduced numbers of oocytes (decreased ovarian reserve) as well as an altered hormonal environment leading to ovulatory dysfunction. No abrupt and clear cutoff level can be defined, but rather a slow steady decline is seen between the ages of 20 and 37 years followed by an accelerated decline over subsequent years, so that spontaneous conceptions and deliveries after the age of 45 are rare, although there are population groups (like Bedouins) with the ability to conceive and deliver at later ages (Menken et al, 1986;Klein and Sauer, 2001;Laufer et al, 2004;Gielchinsky et al, 2006).…”