Delayed Childbearing: Effects on Fertility and the Outcome of Pregnancy

Abstract

In modern societies, the proportion of women who delay childbearing beyond the age of 35 years has greatly increased in recent decades. They are falsely reassured by popular beliefs that advances in new reproductive technologies can compensate for the age-related decline in fertility. Yet age remains the single most important determinant of male and female fertility, either natural or treated. The consequences of advancing maternal age are not only relevant for the risk of natural and assisted conception, but also for the outcome of pregnancy. Although the absolute rate of poor pregnancy outcomes may be low from an individual standpoint, the impact of delaying childbearing from a public health perspective cannot be overestimated and should be in the agenda of public health policies for the years to come. This review summarizes available evidence regarding the impact of delaying childbearing on fertility and pregnancy outcomes.

Effects of aging on the male reproductive system

“…Aging detrimentally affects a woman's reproductive potential, including a high risk of spontaneous abortion, chromosomal abnormalities especially aneuploidies in the offspring, intrauterine growth retardation, and preterm delivery [142]. However, the effects of aging on men's fertility and offspring remain poorly defined.…”

The effects of advanced paternal age on fertility

“…Advanced maternal age is traditionally defined as being greater than 35 years of age. 45 This definition for maternal age was established because it is the age at which women demonstrate a decreased ability to conceive, as well as a prolonged time to achieve pregnancy. 1 The concept of advanced maternal age is synonymous with 'ovarian aging' and is associated with lower oocyte numbers and quality; both of which lead to lower reproductive success.…”

“…6 Indeed, paternal information is often missing from the birth certificate and the age of the father is not reported in 14% of all births. 6 In those cases where the paternal age was reported, the rates of live births per 1000 men increased from 6.1 in 1980 to 8.2 in 2007 among men aged [45][46][47][48][49] years. 6 These statistics are mirrored in advanced countries around the world.…”

Determinants of uterine aging: lessons from rodent models

“…As aging is a cause of cellular senescence [81,82], and decidual senescence is proved to be associated with premature delivery [79], it is conceivable that uterine senescence imposed by maternal aging carries an increased risk for problematic parturition. In humans, the epidemiologic study indicates that increased maternal age is correlated with preterm delivery [15,83,84], and women of higher maternal age, who use assisted reproductive technologies to achieve pregnancy, may experience a higher incidence of preterm birth even when receiving oocytes from young donors [85,86].…”