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The female age is very important in consideration of the probability of becoming pregnant. The increase in infertility rates with aging is well documented and very evident in our society.
The real issue is the quantity and quality of the egg, which translates into the quality of the embryo after fertilization. As women wait longer to have children, more couples have fertility problems due to decreased egg quality and other problems that are more common in older women.
Many couples end up needing advanced treatments like IVF (in vitro fertilization) to help overcome age-related decline in egg quality.
Women’s liberation has brought many benefits to women. However, as women increasingly delay childbearing, our society has done a poor job of educating people about the decline in fertility with aging. Too many couples learn about the impact of age when it may already be too late.
If they had tried for a baby sooner, old-fashioned “bedroom sex” 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 like IVF. However, egg quality is a significant limiting factor.
Individuals vs. Populations
Each individual and couple is unique and may be more or less fertile compared to their average age. Some 30-year-old women already have significant problems with the quality and/or quantity of eggs, and some 43-year-olds may be fertile.
There are also no guarantees that an individual woman will have a slow, smooth decline in her fertility potential as she ages. Although rare, it is possible to have a rapid decline in the quantity and quality of your eggs starting in your teens or early twenties.
Male age and fertility
The age of the male partner doesn’t seem to matter much when it comes to fertility. Reasons for this include:
- All of a woman’s eggs are present at birth. They cannot divide or “replenish” while sperm are constantly produced after puberty in men.
- Eggs age over time, while new sperm are constantly coming off the production line.
- Sperm from older men may have reduced fertilization potential compared to younger men. However, this tends to be an all or nothing effect. If the sperm can fertilize eggs, we generally don’t see poor embryo quality due to reduced sperm quality.
- Sometimes older men are less interested in frequent sex, which may be a factor.
Female age: problems with eggs
- The successful outcome of the pregnancy is closely related to the age of the woman, when using the woman’s own eggs.
- When using donor eggs, 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 of a successful pregnancy.
- Therefore, the age of the ovum is very important, but the age of the uterus is not.
Statistics on female age and fertility decline
Many people are unaware 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 most substantial in the late 1930s and early 1940s.
- Very few women over the age of 44 are still fertile.
- Miscarriage rates also increase substantially as the mother ages.
- IVF success rates begin to decline in your early 30s and decline faster after age 36 or 37.
A 1957 study on the fertility rate by age in women
The study was conducted in a large population that had never used birth control. The researchers measured the relationship between the age of the female partner and fertility. Infertility rates are now higher in the general population than in the population of this study from the 1950s.
This study found:
- At age 30, 7% of couples were infertile
- At age 35, 11% of couples were infertile
- At age 40, 33% of couples were infertile
- At age 45, 87% of couples were infertile Reference: Tietze C: Reproductive period and conception rate among Hutterite women. Fertility and Sterility 1957;8:89-97.
Importance of egg quality for pregnancy outcome
Poor egg quality results in poor embryo quality, which reduces the chances of getting pregnant and having a successful outcome.
Female age and egg quality
Age is a problem, but the real problem of fertility is the quality and quantity of eggs and not the number in the woman’s age. The quantity and quality of eggs in an individual woman may be average for her age, better than average, or worse than average. We know that egg quantity and quality tends to decline significantly in your mid to late 30’s and falls fastest in your late 30’s and early 40’s.
Fertility and “Egg Tests”
Fertility specialists use the following ovarian reserve screening tests to predict the “remaining egg supply” and the ability (reserve) of the ovaries to respond to drug stimulation. These tests are useful. However, they predict the number of eggs left, rather than the quality of those eggs.
- FSH test on day 3
- AMH levels
- Antral follicle count
Treatment Available for Age-Related Fertility Problems: In Vitro Fertilization
Many fertility doctors recommend that women over the age of 38 who are infertile should undergo aggressive fertility treatments and proceed to in vitro fertilization relatively quickly, before fertility potential is lost.
Age limits for in vitro fertilization
All clinics have an upper age limit after which they will not perform IVF with the woman’s own eggs. Most IVF centers will attempt IVF using the female partner’s eggs until about age 43-45.