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Age and fertility

Deferring the commencement of a family is a common choice for women in society today with up to a quarter having their first pregnancy after age 35. This delayed childbirth allows them to establish careers, find stable relationships and achieve financial security.

It is vital, however, to appreciate that age can have a significant effect on ability to become pregnant and to have a normal healthy pregnancy.

Fertility As You Approach 40

The decline in fertility with age is quite remarkable, women under 30 having around a 20 percent chance of becoming pregnant each month while those over 40 have only a 5 percent chance.

While in women the final barrier to having their own children is menopause at around age 50, sperm quality in men only gradually declines with age and problems with libido and erections are more associated with other medical conditions rather than age.

Gynaecological & Obstetric Problems

The older a woman is, the more time she has had to develop gynaecological conditions such as pelvic infections and endometriosis which have the potential to decrease chances of becoming pregnant. A laparoscopy may be performed in the investigation of infertility to screen for these problems.

Women who become pregnant after the age 35 have an increased incidence of high blood pressure and diabetes during pregnancy.

Ovarian Changes

At puberty, women have around 300,000 eggs in their ovaries. Each month usually one matures and up to 1000 others cease maturation and are re-absorbed. By age 40 there may be only several thousand left and they tend to respond poorly to hormonal signals from the pituitary trying to cause them to mature. This lowered response results in the ovary producing less oestrogen and progesterone, hormones which are essential for preparing the lining of the uterus for an embryo to implant and grow.

Oocyte (Egg Changes)

As a woman and her ovaries age, so do the eggs in her ovaries. The eggs are less able to be fertilised by sperm and they have an increased incidence of chromosomal abnormalities. Fertilised eggs which chromosomal abnormalities are less able to continue development causing a lowering of the pregnancy rate and an increase in early miscarriage if pregnancy occurs. We know this because when women receive donated eggs from younger women their chances of pregnancy are much greater than had they used their own eggs.

The eggs of older women, by virtue of their chromosome abnormalities, also produce newborn babies with a higher risk of chromosome abnormalities such as Down Syndrome.

Treatment Options

If a specific cause for infertility is found, a particular treatment may be indicated. If the infertility is unexplained various assisted reproductive technologies may be tried. These range form the relatively simple superovulation followed by timed intrauterine insemination (AIH), to the higher technology and more invasive procedures of gamete intrafallopian transfer (GIFT) or conventional in vitro fertilisation and embryo transfer (IVF-ET). The QFG Office has information sheets on all these procedures.

GIFT appears to be the treatment of chose for unexplained infertility in the older woman. In those 40 years and over GIFT has a pregnancy rate of around 20 percent each treatment cycle compared with 35-40 percent for younger patients whereas IVF-ET yields a pregnancy rate of 5-10 percent in 40 years olds compared with 20 percent per treatment cycle in younger patients.

Another option for older women is to use eggs donated by a younger woman which will yield a higher pregnancy rate and a lower miscarriage rate. Donated eggs and donors themselves are in short supply and those needing donated oocytes often find their own donor from within family or friends. There are many sensitive issues to be dealt with in the use of donated oocytes.


The decrease in fertility with age is an inescapable fact of life. Those seeking pregnancy after the age of 40 should seek the advice of their doctor and explore all options including the medical treatments outlined above, adoption and child-free living.

The QFG has trained counsellors who are happy to discuss all these options with you to help you make the decision which is best for you. They may be accessed through your doctor or the QFG Office.

Keith Harrison,
Queensland Fertility Group

We would like to thank Jo Cranstoun and Dr Keith Harrison for allowing us to reproduce this article on our webpage.


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