Age and Fertility
Fertility in women peaks between the ages of 20 and 24, decreases relatively little until approximately age 30 to 32, and then decreases progressively. Overall, fertility rates are 4-8% lower in women aged 25-29 years, 15-19% lower in those aged 30-34, 26-46% lower in women aged 35-39, and as much as 95% lower for women aged 40-45 years.
Success rates achieved with assisted reproductive technologies (ART) also decline as age increases. The numbers of oocytes retrieved and embryos available are lower, embryo fragmentation rates are higher, and implantation rates are lower in older than in younger women. Although ART pregnancy rates have increased steadily over the past 20 years for women in all age groups, annual reports derived from registry data collected by the Center for Disease Control and Prevention (CDC) in the U.S. since 1989 demonstrate consistently that age is the single most important factor affecting the probability of success with ART. Pregnancy and live birth rates for ART cycles using fresh, non-donor eggs or embryos vary little for women under age 32, but thereafter decrease steadily in a geometric fashion as age increases.
Just as fertility decreases with increasing age, the incidence of clinically recognized miscarriage rises as age advances. Miscarriage rates in natural conception cycles are generally low before age 30 (7-15%) and rise with age, only slightly for ages 30-34 (8-21%), but to a greater extent for ages 35-39 (17-28%) and ages 40 and older (34-52%).
Aging and Male Fertility
The available evidence indicates that pregnancy rates decrease and time to conception increases as male age increases. However, because there is little or no overall measurable decline in male fertility before age 45-50, male factors generally contribute relatively little to the overall age-related decline in fertility.