The relationship between age and fertility
Delayed child bearing is becoming increasingly common in western societies for several reasons: many couples prefer to rear their children only after establishing a stable relationship and financial security, also, there are increasing numbers of late and second marriages. Although pregnancies in women approaching 50 and beyond are occasionally reported, there is a decrease in fertility (the ability to achieve a pregnancy) with advancing age. The decline is gradual over the reproductive life span of the woman; it is particularly noticeable over the age of 30 and accelerates between 35 and 40 so that fertility is almost zero by the age 45.The risk of miscarriage is also increased with ageing e.g. the risk of miscarriage at age 25-29 years is 10% while the risk at age 40-44 is 34%. Furthermore, advanced maternal age is associated withan increased risk of chromsomally abnormal offspring.
Why does fertility decline with increasing age?
Ageing of the ovaries is the most prominent factor and is part of the normal ageing changes that affect all organs and tissues. Most women have about 300,000 eggs in their ovaries at puberty. For each egg that matures and is released (ovulated) during the menstrual cycle, at least 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 e.g. chromosomal abnormalities such as Down syndrome with increasing age. The risk of a chromosomal abnormality in a woman age 20 years is 1/500 while the risk in woman age 45 is 1/20.
Gynaecological problems such as pelvic infection, tubal damage, endometriosis, fibroids, ovulation problems etc tends also to increase with age. As the woman gets older, she has more time to develop these conditions, which will adversely affect her fertility.
Sexual function is also decreased with ageing e.g. libido, frequency of intercourse etc.
The effect of ageing in endometrial receptivity (ability of the endometrium to receive the embryo) is controversial. There is increasing evidence that the receptivity decreases with age.
Ageing does not just affect women, but also men to a much lesser degree. It affects sperm and coital frequency. There is no maximum age at which men are not capable of conceiving a child.
Advanced maternal age increases the risk of autosomal dominant diseases such as Marfans syndrome, neurofibromatosis and achondroplasia.
Investigations of infertility in older women
It is advisable to seek the advice of your doctor/ specialist sooner than later so investigations and treatment can be started without undue delay.
Several tests may be useful in assessing the fertility potential in older woman e.g. blood tests to examine the levels of the hormones FSH, LH, estradiol and inhibin on day 3 of your menstruation.
You will be more likely to be counselled about the risk of miscarriage and chromosomal abnormalities in relation to your age. In addition to the potential complications of pregnancy such as high blood pressure, bleeding and diabetes.
Treatment options for infertility in older women
There are limited options for treating older women who are menopausal or perimenopausal. Older women usually respond poorly to ovarian stimulation and the live birth rates even with IVF treatment are significantly lower than with younger women.
Data adapted from SART report 2000In addition, older are at increased risk of having medical problems in their pregnancies and deliveries. In order to improve the success rate of IVF treatment in older women, some clinics recommend assisted hatching, blastocyst embryo transfer, preimplantation diagnosis and only transfer normal embryos. Furthermore in some countries the transfer of high number of embryos is recommended. Other options of treatment include: