Age and fertility are significantly related in women, and have some connection in men. From a biological standpoint only, the best time to achieve pregnancy and bear a child is in the late teens to early 20s. As age increases, numerous factors can make it harder for a woman to get pregnant, and advanced maternal age also positively correlates to increasing incidence of miscarriage and congenital defects or conditions.
There are several reasons why age and fertility are connected. Younger women have a better supply of viable eggs to be released, hormone levels have less fluctuation and greater stability, and women are less likely, the younger they are, to have yet developed conditions that may interfere with fertility. This doesn’t mean all women easily get pregnant before they reach their 30s, but it does mean that this age group is likely to be more successful in beginning and completing a pregnancy.
As women age, supply of eggs drops dramatically. Women don’t just release a single egg with each ovulation, but release hundreds of poorly formed back-ups that can’t be fertilized. There are a set number of eggs that once used are gone. Supply diminishes with every ovulation, leading to cessation of menstrual periods. At some point age and fertility become completely related because women above a certain age no longer ovulate. There really is a biological clock that partly hinges on a diminishing supply of material needed for pregnancy.
When women reach their 30s, egg supply can be half to two-thirds diminished, and age and fertility also bear relationship because hormones fluctuate as women enter perimenopause. Period regularity begins to change, making conception more challenging. Some periods don’t include ovulation or they lack stable enough hormones to sustain a pregnancy.
These hormonal changes lead to a greater risk for miscarriage. Miscarriage risk is also due to problems with eggs that get fertilized and are not fully healthy, which increases risk for congenital defects or can be so defective they can’t normally develop. Men may also produce less healthy sperm as time goes on, and the offspring of older men may be at greater risk for congenital problems. Generally, males of an advanced age can technically impregnate women.
On the other hand, age and fertility are related to the degree that age increases risk for developing conditions that may interfere with fertility. Both men and women have declining sex hormones as they age, which can result in lack of libido or sexual dysfunction. The genders face equal risk for conditions that require medications affecting libido, like depression or high blood pressure.
Women and men have greater risks for cancer of the reproductive tract as they age, and cancer treatments can induce infertility. Certain diseases in women like sexually transmitted diseases also reduce likelihood of pregnancy, and some viruses create male sterility. Essentially, all older people are more at risk for developing a condition that reduces fertility.
Medical science has evolved many methods to deal with the issues of age and fertility. Women can become pregnant with the use of someone else’s eggs, or complex systems for judging best likelihood of pregnancy along with various treatments can be employed to achieve it. These methods are typically expensive and many are not covered by health insurance, so they won’t be options for everyone. Additionally, chances of achieving pregnancy are still better in younger women than they are for those who pursue fertility treatments.
