While no single age represents a “fertility deadline,” conclusive data shows that the chances of achieving pregnancy is linked with age and it decreases with increased age. However, the rate of this decline is relatively modest until the early 30s.It is also critical to note that there are specific individual variations to reproductive age. Some individuals have been able to have babies naturally even after clocking 46 years. The reasons for this are many, but they centre on the concept that increasing maternal age is generally associated with a decline in both the number and quality of the eggs.
Several studies have confirmed that one of the most critical factors in assessing a couple with fertility problems is the age of the woman. Age affects a woman’s chances of conceiving and having a healthy baby. It means that as a woman gets older, it takes a longer time for her to get pregnant and the risk of not being able to get pregnant increases. Also, the risk of miscarriage and complications during pregnancy and childbirth, such as pre-eclampsia, hypertension and diabetes, as well as fetal chromosomal abnormalities, increases.
Advanced age infertility is attributed to the function of the ovaries. Ovarian function declines as women approach their later reproductive years until menopause. It means that increasing age is associated with lowered fecundity and infertility.
Women experience a decline in natural fertility, which begins in the mid-30s, and they will often reach sterility many years before the complete cessation of menstruation. Indeed, it has been observed that fertility in women declines from 35 years and by the time a woman attains the age of 45 years, it is 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 also slows down and happens less frequently in preparation for menopause. So, as a woman ages, her eggs diminish both in quantity and quality. Starting at about age 32, a woman’s chances of conceiving decreases gradually but significantly. From age 35, the fertility decline speeds up and by age 40, fertility has fallen by half. Such that at 30 years, the chance of conceiving each month is about 20 per cent and at 40, it’s around five per cent.
A study by Henri Leridon, an epidemiologist with the French Institute of Health and Medical Research, showed that women are trying to get pregnant without using fertility drugs or in-vitro fertilisation at age 30. Such women will have a 75 per cent chance of conception ending in a live birth within one year, while 91 per cent will have an IVF treatment ending in a live birth within four years.
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 live birth within four years. And at age 40, 44 per cent of women will have a live birth within one year, while 64 per cent will have a live birth within four years. The trend indicates that fertility decreases with increase in age.
Causes of advanced maternal age infertility
The loss of oocytes from the ovaries is a continual process that begins in the uterus. The ovaries in the female foetus contain between 6 and 7 million oocytes at approximately 20 weeks’ gestation. At birth, 1 to 2 million oocytes remain and only 300 000 to 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 end up in ovulation and 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 will experience premature ovarian failure before age 40. There appears to be a fixed interval through these stages of ovarian function. Women who experience earlier menopause will have a previous 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 specific problems that can contribute to a loss of fertility. These include:
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
Besides, 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 of the ovaries could affect egg quality. Another research this year has indicated that older eggs are less fertile due to reduced cell division and the structures regulating cell division behaving abnormally in older eggs.
In males, aging will result in;
Reduction of the quality of sperm, which affects the sperm’s ability to reach or fertilize an egg. Men also produce a lower amount of 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 diseases, such as hypertension
The change in 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.
To be continued…