Female Age

Studies of pregnancy rates and age support the idea that female fertility declines with age. If you have not considered age as a factor in your infertility, you may be unaware of these pregnancy trends.

• Pregnancy rates begin to decline slowly, beginning in the late 20s.
• Throughout the late 30s and early 40s there is an even greater decline in pregnancy rates.
• Few pregnancies are recorded after the age of 45.
• By the age of 30, 7% of couples are infertile.
• By the age of 40, 33% of couples are infertile.

 

Why do women lose their fertility as they age?

Egg Quantity

Egg quantity refers to the number of eggs that you have in your ovaries. At birth, each woman has about 1,000,000 eggs available for fertilization. Only a small minority of these eggs will have the proper quality for fertilization. As you age, the number of eggs in your ovaries begins to decrease. By the time you begin menstruating you have about 400,000 eggs available for fertilization. Each month you may produce several eggs for ovulation, but many will never have the opportunity to achieve fertilization. By the time menopause arrives, most women only have a few hundred eggs left in their ovaries.

Because the number of eggs that you have available for fertilization declines with age, this can make it more difficult to become pregnant as you grow older.

Egg Quality

Egg quality refers to how ready and able your eggs are to become fertilized. The eggs need to have the right shape, health, and chromosomes in order to be able to develop into an embryo and, eventually, a baby. They also need to be able to combine with sperm in order to produce a child. These characteristics all contribute to your egg quality.

Unfortunately, egg quality also changes over time. As you age, your eggs become weaker, and less able to form a healthy embryo. Your eggs also begin to decrease in number, leaving fewer and fewer quality eggs available for fertilization. A woman of 40 typically has lower egg quality than a woman of 20.

This is not to say that your eggs are of poor quality just because you're aging. Many younger women have poor quality eggs while some older women have very high quality eggs. On average however, egg quality does decline with age.

Ovulation disorders

There are many causes of oligoovulation (irregular ovulation) and anovulation (no ovulation) including:

• Ovarian failure
• Polycystic ovarian syndrome, PCOS
• Thyroid dysfunction
• Excessive exercise, stress and anorexia

Tubal disease

Any condition that impedes, or blocks, egg transport through the tubes can cause infertility. Pelvic infections (pelvic inflammatory disease), caused by a variety of microorganisms including Chlamydia, can damage the fallopian tubes. See our section of Fertility Surgery for details of possible surgical treatment options. In many cases surgery in combination with IVF is the most successful approach.

Endometriosis

Endometriosis occurs when endometrium, the tissue which normally lines the uterus (womb), is found outside the uterus, usually in the pelvis - behind the uterus or on the woman’s ovaries. This tissue responds to hormones in the same way as the lining of the uterus so it bleeds each month at period time. This bleeding can cause pain and can also lead to scarring and tissue damage in the pelvis. If it occurs on the ovaries, it can cause cysts of endometriosis or “chocolate cysts” so called because they contain old blood which is very dark in colour.

It is thought that one in ten women will develop endometriosis. However it affects individual women in very different ways. In women who present with pain due to the condition, two thirds will have no difficulty conceiving. However, of all women presenting with fertility problems, endometriosis is found in approximately one third. It is therefore an important factor which can affect fertility.

Endometriosis is graded as minimal, mild, moderate and severe, depending on the extent and severity of the tissue damage. Minimal and mild endometriosis may come and go over the years and never cause any specific problems. However it may be associated with delay in conceiving and there is evidence that surgical treatment improves fertility. It is unclear how this minimal or mild endometriosis reduces fertility but it may do so by causing inflammation in the pelvis with the release of factors which are toxic to sperm and embryos. Moderate and severe endometriosis behaves in a more aggressive manner, often causing significant pain and infertility. Cysts and scarring of the ovaries and fallopian tubes can interfere with ovulation and prevent eggs from reaching sperm in the fallopian tubes. At present we cannot predict accurately who will develop aggressive endometriosis. Regular reviews with a gynaecologist are important. Women known to have endometriosis should plan to start their families by their late twenties or early thirties if at all possible.

The treatment of endometriosis is complex and will vary from woman to woman. In those trying to conceive, surgery is the first line of treatment.  Surgery aims to remove or ablate (destroy) visible endometriosis and return the pelvis to its normal state. Ablation is performed using laser or diathermy (an electric current). A keyhole/laparoscopic approach to surgery is preferable to open operation as the recovery is faster and the incidence of post-operative scarring is lower. If a good result is obtained with the surgery i.e. if most endometriosis and scarring can be removed and if the fallopian tubes are not blocked, up to 50% of couples will conceive. If the couple does not conceive following surgery, they should be offered IUI (intrauterine insemination) or IVF (in-vitro fertilization). IUI is only appropriate if the women is 35 or under and if the endometriosis is minimal or mild. IVF is preferable for all others.

Medical or hormonal treatment for endometriosis is good for pain relief but not for fertility. In those trying to conceive, medical treatment may be used for 2-3 months before or after surgery or prior to an IVF cycle but prolonged treatment acts as contraception and does not improve fertility. Alternative treatments such as Chinese Medicine with herbs and acupuncture can be very useful, particularly in women with pain who are undergoing fertility treatment.