The real issue is egg quantity and quality - which translates into embryo quality after fertilization. As women wait longer to have children, more couples have fertility problems due to a decline in egg quality, and due to other issues that are more common in older women.
Many couples end up needing advanced treatments such as IVF (in vitro fertilization) to help overcome the age related decline in egg quality.
Women's liberation has brought many advantages to women. However, as women increasingly delay childbearing, our society has done a poor job of educating people about the fertility decline with aging. Too many couples learn about the impact of age when it may already be too late.
If they had tried to have a baby sooner, old-fashioned "sex in the bedroom" could have built the family. The American Society for Reproductive Medicine said it well:
"As women delay childbearing, there is now an unrealistic expectation that medical science can undo the effects of aging."
We do our best to overcome advancing age with fertility treatments such as IVF. However, egg quality is a significant limiting factor.
Individuals vs. Populations
Every individual and couple is unique and could be more fertile or less fertile as compared to the average for their age. Some 30 year olds already have significant egg quality and/or quantity issues and some 43 year olds can be fertile.
There are also no guarantees that an individual woman will have a slow and smooth drop in her fertility potential as she ages. Although rare, it is possible to have a rapid decline in egg quantity and quality as early as the teens or twenties.
Male Age and Fertility
The age of the male partner does not appear to matter much when it comes to fertility. Reasons for this include:
- All of a woman's eggs are present at birth. They can not divide or be "resupplied", whereas sperm are produced constantly after puberty in men.
- Eggs age over time, while new sperm are constantly coming off the production line.
- Sperm from older men can have a reduced fertilizing potential as compared to younger men. However, this tends to be an all or none effect. If the sperm can fertilize eggs - we generally don't see poor embryo quality due to reduced sperm quality.
- Sometimes older men have less interest in frequent intercourse, which can be a factor.
- Successful pregnancy outcome is very much related to female age - when using the woman's own eggs.
- When donor eggs are being used, the age of the egg donor is the important issue.
- With egg donation, the age of the recipient woman has very little impact on the chance for successful pregnancy.
- Therefore, the age of the egg is very important, but the age of the uterus is not.
Many people are not aware of the decline in fertility as the age of the female partner increases.
- There is a slow decline in pregnancy rates in the early 30's.
- The decline is more substantial in the late 30's and early 40's.
- Very few women over 44 are still fertile.
- Miscarriage rates also increase substantially as the mother ages.
- In vitro fertilization success rates start dropping in the early 30's and fall faster starting at about age 36 or 37.
The study was on a large population that never used birth control. The investigators measured the relationship between the age of the female partner and fertility. Infertility rates are now higher in the general population than for the population in this study from the 1950s.
This study found:
- By age 30, 7% of couples were infertile
- By age 35, 11% of couples were infertile
- By age 40, 33% of couples were infertile
- At age 45, 87% of couples were infertile Reference: Tietze C: Reproductive span and rate of conception among Hutterite women. Fertility and Sterility 1957;8:89-97.
Poor egg quality results in poor embryo quality, which reduces the chances for becoming pregnant and having a successful outcome.
Female Age and Egg Quality
Age is one issue, but the real fertility issue is egg quality and quantity and not the number in a woman's age. Egg quantity and quality in an individual woman can be average for her age, better than average, or worse than average. We know that egg quantity and quality tends to decline significantly in the mid to late 30s and fall faster in the late thirties and early 40s.
Fertility and "Egg Tests"
The following ovarian reserve screening tests are used by fertility specialists to predict the "remaining egg supply" and the ability (reserve) of the ovaries to respond to stimulation with drugs. These tests are helpful. However, they predict the quantity of eggs remaining - rather than the quality of those eggs.
- Day 3 FSH testing
- AMH levels
- Antral follicle counts
Many fertility doctors recommend that women over about 38 that are infertile should have aggressive fertility treatments and proceed to in vitro fertilization relatively quickly - before fertility potential is lost.
(Source) Advanced Fertility Center of Chicago
