Age & Infertility
Age-related decline in female fecundity
Delaying pregnancy is becoming increasingly common all over the world for several reasons. The number of women in their late 30’s and 40’s attempting pregnancy has increased in recent years.
Few reasons are :
- Delaying pregnancy until careers are established
- Waiting for sound financial security
- Being unsure about the desire of parenthood
- Late marriages
with advancing age, many biological changes take place that work against conceiving and carrying the pregnancy to term. It is estimated that the chance of becoming pregnant in any one month is about 20% in women under 30, but only 5% in women over 40. After age 40, there is a sharp decline, also the chance of miscarriage and chromosomal abnormalities increases with the age. Even the success of IVF and other similar procedures decreases with advancing age. There are several explanations for this change in fertility, including medical conditions, changes in ovarian function and alterations in the eggs released by the ovaries. Aging does not just affect women, changes in fertility and sexual functioning do occur in men as they age. The tests tend to get slightly smaller and softer with Age. Sperm morphology (shape) & motility also tend to decline. Despite these changes, there is no age limit at which men are not capable of conceiving a child. Sexual functioning in men may also change with aging and decrease in libido may be due to decrease in ‘testosterone’ level, monotony, mental tension, overburdened with work , lack of time, etc.
- fecundity [ the monthly chance of conception] declines with advancing age. It has been estimated that fecundity declines gradually from the age of 30 years and reaches almost zero by 45 years, and it is because of normal changes which occur in the ovaries with aging.
- The hypothalamus [located in brain] stimulates the pituitary gland to release follicle stimulating hormone [FSH] and luteinizing hormone [LH]. These hormones are secreted into the blood stream and control the growth of oocyte[egg], and the production of the female hormone, estrogen, by the ovaries.
- Most women have about 300,000 eggs in their ovaries at puberty. Each egg that matures is released [ovulated] during the menstrual cycle, atleast 500 eggs do not mature and are absorbed by the body. By the time the woman reaches menopause which usually occurs between 50-55 years , there are only several thousands eggs remaining. As the woman ages, the remaining eggs in her ovaries also age, making them less capable of fertilization and their embryos less capable of implanting.
- Fertilization is associated with a higher risk of genetic abnormalities such as down syndrome. When eggs with chromosomal problems are fertilized, they are less likely to survive and grow, and for this reason , women who are over 40 are at increased risk of miscarriage.