For those who dream of being parents, pregnancy problems can be tremendously frustrating and disappointing. In recent decades, scientists have developed a wide range of approaches to help struggling couples have healthy babies. And NIH-funded studies are continuing to search for even better ways to overcome the challenges of infertility.
Infertility is a fairly common condition. It affects about 1 in 10 couples who are trying to have a baby. Infertility can be traced to the man in about a third of these cases and to the woman in another third. The rest of the time, the difficulties lie with both partners or no cause can be found.
“Although there are many known causes of infertility, there are still some cases of fertility impairments that we don’t understand,” says NIH’s Dr. Louis V. DePaolo, an expert in fertility research. “We’re constantly discovering new molecules that are vital to the fertility-regulating process.” By learning more about these molecules and other factors, scientists hope to find new and improved ways to prevent or treat infertility.
Knowing the underlying causes of infertility is important because it can help couples choose the best therapy. “Since there are many causes, a treatment that works for one person might not be the best choice for another,” DePaolo says. The most common treatments today are surgery or medication.
Fertility troubles can arise in any of the steps needed for a successful pregnancy. To get pregnant, a woman’s body must first release an egg from one of her ovaries, a process called ovulation. The man’s sperm then has to join with, or “fertilize,” the egg. The egg must then travel through a passageway known as the fallopian tube and head toward the woman’s uterus (womb). The fertilized egg must then attach to the inside of the uterus (implantation).
Infertility can be related to a man if there are problems with the number, shape, or movement of sperm. These glitches can make it hard for the sperm to fertilize the egg. About 1 in 5 infertile men have sperm troubles because of a hormone imbalance, which can sometimes be corrected with medication.
“Another common identifiable cause of male infertility occurs when a man has large veins around the testicle, which makes the whole scrotum warmer than it should be. The heat decreases the production and quality of sperm,” says Dr. Peter N. Schlegel, who specializes in treating male infertility at Cornell University. This condition, called varicoceles, is usually harmless, but it can be corrected with surgery if it’s causing infertility. Surgery can also help to remove blockages that prevent sperm release.
“There are also genetic causes of low sperm production, which are probably more common than we can identify, because we don’t yet understand all the causes of male infertility,” Schlegel says.
For women, the most common cause of infertility has to do with ovulation problems, which affect about 40% of women who have pregnancy trouble. “Ovulatory problems occur when a woman ovulates irregularly or not at all,” says Dr. Linda Giudice, a reproductive health expert at the University of California, San Francisco. “Causes can include stress-related lack of or irregular periods, polycystic ovary syndrome (PCOS), advanced maternal age, and a variety of other possible factors, like hormone issues that can interrupt normal ovulation.”
Other common causes of female infertility include blocked fallopian tubes or conditions that affect the health of the egg or its implantation after fertilization.
In the United States, older maternal age is a growing contributor to fertility problems. About 1 in 5 women nationwide now have their first child after age 35. Once a woman reaches this age, fertility complications arise in about 1 of every 3 couples trying to have a baby. Studies suggest that after age 30, a woman’s chances of getting pregnant decrease every year, especially after age 37.
“One of the biggest challenges in infertility treatment is related to advanced maternal age, when the egg quality and egg numbers decrease,” Giudice says. “For older women, treatment can usually help to achieve ovulation, but the problem usually lies in not having good-quality eggs.”
Aging not only reduces the likelihood of having a baby. It also raises the chances of miscarriage or having a child with certain health problems. High-risk pregnancies are also more likely as women get older.
In some cases, infertility can be corrected through lifestyle changes, such as losing weight or stopping tobacco use. If this doesn’t work, doctors may recommend medication, surgery, artificial insemination (in which a woman is injected with specially prepared sperm), or assisted reproductive technology, which is usually the most expensive and complex option. Assisted reproductive technology includes different methods for fertilizing eggs, usually outside of the body.
Giudice and her colleagues are among many NIH-supported scientists studying the pregnancy process. “We’re examining what happens during certain stages of egg development, what happens when women are of advanced maternal age or when they have a condition called endometriosis, which affects egg quality and the lining of the uterus and its receptiveness to implantation,” Giudice says.
Schlegel and his coworkers are among those focusing on the underlying causes of male infertility. “We’re looking at factors called micro-RNAs, which are small bits of genetic material that are made by the body to help regulate how a wide variety of body parts work, including the areas of the testicle involved in sperm production,” Schlegel says. “We’re also looking at other genetic causes of infertility and ways to improve or create sperm for men who can’t make them.”
For couples who have tried to have a baby without success, experts recommend seeking medical help after at least a year of trying if the woman is younger than 35, or after 6 months if the women is age 35 or older. It’s also a good idea for couples to talk with a health care provider before even trying to get pregnant.
“If you’re planning to start a family, your health before you begin trying is very important,” DePaolo says. “By being healthy, you have a better chance of being able to conceive within a normal amount of time, and you’re more likely to have healthy offspring as well.”