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The decline of fecundity with age

1988; Elsevier BV; Volume: 10; Linguagem: Inglês

10.1016/0378-5122(88)90004-7

1873-4111

Alfred Spira,

Reproductive Biology and Fertility

Historical studies all indicate a decline in fertility with age. The artificial insemination data from a program carried out in France since 1973 related to women whose husbands were permanently sterile because of azoospermia. During the first 2 cycles only 1 insemination was performed per cycle using frozen semen from married donors aged 45 years or under. Another set of data comprised the results of in vitro fertilization with embryo transfer performed by 48 groups in France in 1986. Altogether 5990 attempts were analyzed and the results were expressed as the number of pregnancies over the number of attempts and as the number of pregnancies over the number of transfers. The fecundity decline began in the 31-35 age group and it was marked beyond age 35. The probability of success with artificial insemination data over 12 cycles (73% and 74%, respectively, for the 2 groups of women aged under 31) dropped to 61% in the 31-35 age group and to 54% in those aged over 35 connected to a steady fall in the number of ova collected (4.3 before age 24 and 3 after age 40). Factors associated with fecundability were the duration of the menstrual cycle, pelvic inflammatory diseases (PID) tubal diseases 915-20% of infertility), and age-related spontaneous abortion. The proportion of aborted fetuses exhibiting chromosomal abnormalities was 17% in the over 40 age group vs. 8% in the under 20 age group. The relation between age and trisomy 21 is well-known. Sperm count of around 100 x 106/ml at age 20 takes 60 years to fall to 40 x 106/ml when a man is in his 80s. A significant age-related decrease after age 45 occurs in sperm motility. In the male there is no clear upper age limit for fertility, only a general decline safer 40. A mathematical model of fecundability showed that after age 25 the decline in fecundability is determined at least in part by declining female fecundity.