The American Fertility Association

More than 15% of couples in this country have difficulty conceiving a child. Delayed childbearing has resulted in more women in their late 30s and early 40s attempting conception than ever before. In fact, 20% of women in the United States now have their first child after age 35.

Some women seeking to conceive after age 40 have no difficulty in achieving a pregnancy. For those who do, however, prompt and thorough evaluation and aggressive treatment are crucial. The probability of having a baby decreases 3-5 % per year after the age of 30, and at a faster rate after 40. Unfortunately, as women age they also have a higher chance of miscarrying.

At birth, a woman has all the eggs she will ever have. As an egg ages, it is more likely to develop a chromosomal abnormality. A fertilized egg with abnormal chromosomes is the single most common cause of miscarriage: at least half of all miscarriages are due to abnormal chromosomes. A woman in her 20s has only a 12-15% chance of having a miscarriage each time she becomes pregnant. On the other hand, a woman in her 40s faces a 50% risk of miscarriage.

Trying to conceive for one year before an infertility evaluation may not be appropriate in women over 40. If a woman is over 40 and the couple has been trying to conceive for over six months, a basic infertility evaluation is indicated.