Age and Infertility by Prof Oladapo Ashiru OFR
Several studies have confirmed that one of the most important factors in assessing a couple with fertility problems is the age of the woman. Age affects a woman’s chances of conceiving and have a healthy baby. This means that as a woman ages, it takes a longer time for her to conceive and the risk of not being able to get pregnant increases.
Also, the risk of miscarriage, and complications in pregnancy and childbirth, such as pre-eclampsia, hypertension and diabetes, as well as fetal chromosomal abnormalities, increases.
Advanced age infertility can be attributed to function of the ovaries. Ovarian function declines as women approach their later reproductive years until menopause, which means that increasing age is associated with lowered fecundity and infertility.
Women experience a decline in natural fertility that begins in the mid-30s, and they will often reach sterility many years before the complete cessation of menses. Indeed, it has been observed that fertility in women declines from 35 years and by 45 years it’s almost down to nine per cent.
Women are born with all the eggs they will ever have in their entire life. After puberty, female fertility increases and then decreases. Over time, ovulation slows down and happens less frequently in preparation for menopause. So as a woman ages, her eggs diminishes in quantity and quality.
Starting at about age 32, a woman’s chances of conceiving decrease gradually but significantly. From age 35, her fertility decline speeds up and by age 40, fertility has fallen by half, such that at 30, the chances of conceiving each month are about 20 per cent. At 40 it’s around five per cent.
According to a study by Henri Leridon, an epidemiologist with the French Institute of Health and Medical Research, women trying to get pregnant, without using fertility drugs or In vitro fertilization at age 30, will have a 75 per cent chance of conception ending in a live birth within one year.
At age 35, 66 per cent of women will have a conception ending in a live birth within one year, while 84 per cent will have a conception ending in a live birth within four years. And at age 40, 44 per cent of women will have a conception ending in a live birth within one year, while 64 per cent will have a conception ending in a live birth within four years. This shows that fertility decreases with increase in age.
Causes of advanced maternal age infertility
One of the major causes of advanced maternal age infertility is ovarian aging
The loss of oocytes from the ovaries is a continual process that begins in utero. The ovaries in the female fetus contain 6 to 7 million oocytes at approximately 20 weeks’ gestation. At birth, 1 to 2 million oocytes remain, and only between300, 000 and 500, 000 are present at the onset of puberty. This process continues until menopause, when only a few hundred oocytes remain.
During the reproductive years, 400 to 500 oocytes will be ovulated. Majority of oocytes are lost through apoptosis, or programmed cell death. As the ovarian follicular pool decreases, women will experience infertility, sterility, cycle shortening, menstrual irregularity and finally menopause.
In the western countries, the mean age of menopause is 51, and one per cent of women will experience premature ovarian failure before age 40. There appears to be a fixed interval through these stages of ovarian function. Women who experience an earlier menopause will have an earlier loss of fertility; therefore, approximately 10 per cent of women will have decreased ovarian function in their early to mid-30s!
Increasing age also increases the risk for certain problems that can contribute to a loss of fertility. These include:
- Uterine fibroids
- Tubal disease, a general term that describes any number of infections that affect the fallopian tubes
- Genetic abnormalities of the remaining eggs, which can make them less viable or increase the likelihood that an infant will have conditions such as Down syndrome
- In addition, lifestyle and environmental factors can combine with age-related factors to significantly decrease fertility.
- A study done in 2016 suggested that excessive scarring and inflammation on the ovaries could affect egg quality. Another study this year has suggested that older eggs are less fertile due to poor cell division and the structures regulating cell division behaving abnormally in older eggs.
In males, age is known to
- Reduce the quality of sperm, which affects the sperm’s ability to reach or fertilize an egg. Men also produce fewer sperm as they age.
- Genetic abnormalities of the sperm, which can reduce the chances of their partner becoming pregnant or increase the likelihood of miscarriage or of an infant having a condition such as Down syndrome
- Erectile dysfunction, which can be affected by decreasing testosterone levels as a man ages or by medications for age-related conditions such as hypertension
- Changes to the reproductive tissues or organs. For example, testicle volume decreases with age. Also, men may have an enlarged prostate, which can cause problems with ejaculations.