While the term infertility is well known, its definition is less so. Many know that it means a woman is unable to get pregnant, but what are the specific parameters? Dr. Jessica Scotchie, a reproductive endocrinology and infertility physician with Tennessee Reproductive Medicine, explains, “Assuming that a woman is having regular, predictable menstrual cycles, infertility is defined as the inability to conceive after 12 months of attempted conception for women under 35, and after six months of attempts without conception for women over 35.”
What Causes It
In any given month, a couple attempting to get pregnant has about a 15-20% chance of conceiving a child. If certain issues are present, those chances can drop substantially. According to Dr. Scotchie, there’s not one specific cause, but rather a number of circumstances that can lead to infertility. “A combination of problems can be associated with infertility including ovulation problems, anatomical issues, sperm production issues, and more.”
Some of the most common causes of infertility include:
Polycystic Ovarian Syndrome (PCOS)
The Centers for Disease Control & Prevention reports that PCOS is the most common cause of infertility in women. Caused by a hormonal imbalance that results in small cysts developing on the ovaries, this condition affects ovulation and can lead to irregular periods or even a lack of periods. And while as many as 10% of women of childbearing age have PCOS, fewer than half are diagnosed.
A painful disorder for many of those affected, endometriosis is a condition in which tissue that lines the uterus grows in places outside of the uterus, most commonly behind the uterus but also in the fallopian tubes or ovaries. The condition affects fertility in many ways, causing inflammation and sometimes tubal blockage. It can be difficult to diagnose because sometimes the only symptom is infertility, as not all women with the condition have pain. Endometriosis is diagnosed surgically, and removing it can improve fertility. Younger women who have endometriosis are likely to have an easier time conceiving than older women, since their eggs are younger and healthier.
Being 35 or Older
Getting pregnant becomes increasingly difficult with each passing year, especially once you hit 35. This is because a woman is born with all the eggs she’ll ever produce. As she ages, she’ll lose eggs, and those that she still has can lose quality. “There is a huge difference in a 35-year-old egg and a 40-year-old egg,” Dr. Scotchie explains. For women in their 20s, many of the eggs are still healthy and normal, whereas approximately 80-90% of the eggs of women in their 40s are abnormal.
Unhealthy Body Weight
Being overweight or underweight can affect a woman’s chances of getting pregnant too. Successful ovulation is closely tied to a woman’s estrogen levels. In someone who is overweight, her body may produce more estrogen than the body needs, which can prevent regular ovulation. On the flipside, a woman who is underweight may not produce enough estrogen, which can also inhibit regular ovulation or stop her periods altogether.
As many as half of all cases of infertility can be caused by male factors like low sperm production, immobile sperm, or blockages that can prevent proper sperm delivery. These issues can be caused by illness, injury, or lifestyle, or a man may be born with problems that affect his sperm.
According to Dr. Scotchie, “About 15% of patients’ infertility is unexplained.” In these situations, fertility tests will likely come back normal or with only minor abnormalities. Having unexplained infertility does not mean nothing is wrong – there are components about fertility that are impossible to test in a woman (such as fertilization and embryo development). Even in these cases, treatment is highly effective for most couples.