Fertility by Age

Age affects both men and women′s chances of having a successful pregnancy. After puberty, the initiation of female fertility is marked by the onset of ovulation and menstruation. Men can stay fertile for a much longer period than women. However, male fertility also declines with age, nevertheless much slower than the decline observed in female fertility. While many men continue to be fertile into their 50’s and beyond, the percentage of men with sperm disorders increases with age.

It is important for you and your spouse to understand the impact of age on fertility, pregnancy, and childbirth and to what extent medical technology can be of assistance to you.


Does age affects fertility in women?

Yes! Like it or not, age remains the most important factor of fertility. As a woman gets older, conditions that could possibly affect her fertility increase. Here is why you shouldn’t wait until you are in your 40s to fulfill your dream of having a family.

A woman’s fertility peaks in her 20’s and starts to declines from around the age of 30, dropping down more steeply from the age of 35. A healthy 30-year-old has about a 20% chance each month of getting pregnant, while a healthy 40-year-old has about a 5% chance each month.

Women do not remain fertile until menopause. The average age for menopause is 51, but sometime most women are unable to have a successful pregnancy in their mid-40s. These percentages are true for natural conception as well as conception using fertility treatment, including in vitro fertilization (IVF).

How does fertility change with age?

The age-related loss of female fertilityhappens because both, the quality and the quantity of eggs, gradually decline.

1. Egg Quantity (Ovarian Reserve): The number of eggs in women, gradually declines with age. This decrease of egg-containing follicles in the ovaries, is called "loss of ovarian reserve..”

At the time of birth the ovaries of a girl contain around one million eggs.At the time of puberty the number has gone down to approximately 100,000 and this pool of follicles is gradually used up.

As this ovarian reserve get used up over time , the follicles become less and less sensitive to hormonal stimulation. So, at a later age they require more stimulation to mature and ovulate.

In the beginning of puberty , periods may come closer together resulting in short cycles that are 21 to 25 days apart. Eventually, the follicles don’t respond well enough to consistently ovulate, resulting in short, irregular cycles.

Usually, the decrease in ovarian reserve is related to increasing age, but it is strongly linked to smoking, family history of premature menopause, genetic abnormalities, previous ovarian surgery and parental consanguinity, endometriosis and Vitamin D deficiency.

If a woman has a low ovarian reserve, the chance of becoming pregnant decreases, hence the chance for pregnancy is still directly related to the age of the patient: e.g. a 28 year old patient with a reduced ovarian reserve still has a better chance of conceiving and having a healthy child, compared to a patients in her 40s with the same ovarian reserve. There are medical tests for ovarian reserve, but none have been proven to predict the possibility of becoming pregnant reliably. These tests do not determine whether or not a woman can become pregnant, but they can determine that age-related changes of the ovaries have begun.

Women with poor ovarian reserve have a lower chance of becoming pregnant, than women with normal ovarian reserve in their same age group. No single test nor any combination of tests is 100% accurate.

To test for ovarian reserve, FSH , Follicle Stimulating Hormone is sampled from blood on day-3, and estrogen levels in blood are tested on days 2, 3 and 4 of the menstrual cycle.

High levels of FSH in combination with low levels ofestrogen indicate that ovarian reserve is low. However, FSH increase, is a very late indicator of low ovarian reseve, and many women with diminished ovarian reserve will have normal or slightly elevated FSH levels on day 3. Abnormal day-3 FSH levels, especially confirmed when repeated, showreduced ovarian reserve. Today, the most reliable test of ovarian reserve is the ultrasound assessment of follicle numbers in the beginning of the cycle, called the Antral Follicle Count or AFC.

A more accurate test can be done to measure the ovarian reserve, it’s called AMH test. It measures a hormone called Anti-Müllerian Hormone which is a substance produced by granulosa cells in ovarian follicles.
AMH levels slightly vary throughout the menstrual cycle. Therefore, this hormone can be tested any time of a woman’s cycle.
AMH levels decrease with age. The higher the AMH, the higher the quantity of eggs remaining in a woman’s ovaries. However, it’s important to mention that very high AMH values can sometimes be an indicator of Polycystic Ovarian Syndrome (PCOS).
In general, higher AMH values are associated with higher response to ovarian stimulation as hence more eggs at the time of pick-up during IVF.

2. Egg Quality: No matter how you take care of yourself, you cannot slow down ovarian aging. A woman’s age is the most precise test of egg quality. By the time women reach their 40s, most of their eggs will be of poor quality. Poor quality is directly related to genetic information of the eggs.

Genetically abnormal eggs decrease the chance of a successful pregnancy, and increase the risk of miscarriage and having genetically abnormal (aneuploid) embryos. Generally, a normal egg and sperm should have 23 chromosomes each. After fertilisation the resulting embryo will have46 chromosomes, which is chromosomatically the normal amount. As a woman gets older, more and more of her eggs have either too few or too many chromosomes.

That means that if fertilisation occurs it will result in an aneuploid embryos with too many or too few chromosomes or displaced or missing chromosomes that will prevent a development of a healthy embryo. This helps explain the lower chance of pregnancy and higher chance of miscarriage in older women. In fact, after having genetically normal embryos being transferred in IVF/PGS (genetic screening of embryos) cycles, the chances of a successful pregnancy are the same between a 25 year old and a 45 year old patient.

3. Menopausal period or the end of menstruation marks the end of fertility, causing a woman to no longer be able to become pregnant. Although potential age-related infertility can be expected to end 5 to 10 years before the age of menopause especially the oocytes being released during this life-span will have a higher risk of being genetically abnormal.


Changes in sexual function: LIBIDO and ERECTION

Like women, fertility also varies from man to man and age is not a perfect predictor of male fertility. Not all men experience significant changes in reproductive or sexual functioning as they age, especially men who maintain good health over the years.

Decrease in sex drive (libido) may happen in some men. Sexual responses may become slower and less intense. Aging does not prevent a man from being able to enjoy sexual relationships, but with aging several factors related to libido, like serum testosterone levels, do decrease.

Erectile dysfunction may affect man in any age. However, more elderly man might be affected due to changes in the endocrine profile. Moreover, it might be also be a result of medical and, or psychological problems.

Sperm Abnormalities in Aging Men

Sperm quality does reduce with age, but in general it is not a factor before the age of 60 years. Changes in fertility and sexual functioning maybe more noticeable in women, but with age men can be affected too.

Also, as men grow older their testes tend to get smaller and softer, and sperm morphology (shape) and motility (movement) tend to decline. Therefore, the risk of genetic disorders in their sperm increases.

Despite these changes, there is no age limit for man to father a child. However, there is enough evidence to support this, as men in their 60s and 70s have been able to conceive with younger partners.

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