Advances in fertility treatment have progressed significantly since the 1970s, when the first IVF test tube baby was born in the UK. But it can still take quite some time to recognize and diagnose fertility problems. As a result, a lot of women who have successful fertility treatment tend to be older mothers.

It is generally considered that an older mother carries a greater risk of physiological problems to an unborn child. This can be true. However, teenage mothers pose a similar risk ratio, but for very different reasons. Older mothers can give birth to perfectly healthy babies. Furthermore, the age at which women have children is increasing due to the demands of 21st century life, employment and society to the point where it is now not uncommon for women to have children in their 40s. Various controversial fertility treatments have even made it possible for women in their 50s and 60s to conceive.

The biological optimum age for a woman to bear a child is from age 20 (when the body has reached full physical maturity) to 35 years, after which certain risks increase. So, when is a mother considered an "older" mother?

Some would suggest in their 40s or 50s. However, 35-plus years is when a woman is considered biologically more likely to encounter complications during pregnancy. A few of the more common complications include the following:

Chronic Illness. Older women are more likely to suffer from chronic illnesses during pregnancy. These conditions are not usually life-threatening to someone who is not pregnant. But, during pregnancy, if they are not controlled properly, they can become fatal to the older expectant mother or unborn child. These illnesses include high blood pressure, diabetes and thyroid problems.

Labour and delivery. Most women who have had children before and after the age of 35 admit that the older they are during labour, the more exhausting and painful the experience is. Most do have a natural birth; however, in this age group, there are higher incidents of problems during labor. These include hemorrhaging and placental abruption, which is when the placenta separates prematurely. As a result, they are more likely to have a cesarean section, which can come with its own set of complications.

Fetal abnormality and birth defects. These are generally caused by chromosomal disorders in the pregnancies of older women. Ova (eggs) and sperm are supposed to contain 13 chromosomes each (which are codes for genetic make-up), so a fertilized egg that becomes a fetus should contain 26 chromosomes. In older women, the egg occasionally contains 14 chromosomes, and this leads to genetic abnormalities. Usually, an abnormal fetus will self-abort, hence the higher risk of miscarriages for older women. But occasionally the child will be born with birth defects, which can be both mental and physical. Down syndrome is the most common birth defect that is more prevalent in older women. Apparently, the relationship between the mother's age and the possibility of the occurrence of Down syndrome is as follows:

At age 20, there is a 1 in 1,667 chance of Down Syndrome.

At age 30, there is a 1 in 385 chance of Down Syndrome.

At age 40, there is a 1 in 106 chance of Down Syndrome.