Intrauterine insemination (IUI) is a procedure that treats infertility. IUI boosts the chances of pregnancy by placing specially prepared sperm directly in the uterus, the organ in which a baby develops. Another name for the procedure is artificial insemination.

With IUI, the sperm are inserted around the time an ovary releases one or more eggs. The hoped-for outcome is for the sperm and egg to unite in the fallopian tube, which connects the uterus to the ovaries. If this happens, it leads to pregnancy.

Intrauterine insemination can be timed with a person's menstrual cycle. During the monthly cycle, one of the two ovaries releases an egg. Or fertility medicines may be used along with IUI to help the ovaries produce eggs. The exact method used depends on the reasons for infertility.

A couple's or a person's ability to become pregnant depends on various things. Intrauterine insemination is used most often in people who have:

• Donor sperm. This is sperm donated by someone who may be known or unknown to you. It's an option if you're single, your partner doesn't have sperm or the quality of the sperm is too low to conceive with. For people who need to use donor sperm to get pregnant, intrauterine insemination is most commonly used to achieve pregnancy. Donor sperm is obtained from certified labs and thawed before the IUI procedure.
• Unexplained infertility. Often, IUI is done as a first treatment for unexplained infertility. Medicines that help the ovaries produce eggs are commonly used along with it.
• Infertility related to endometriosis. Fertility problems can happen when tissue that's like the lining of the uterus grows outside the uterus. This is called endometriosis. Often, the first treatment approach for this cause of infertility is to use medicines to obtain a good-quality egg along with doing IUI.
• Mild male factor infertility. Another name for this is subfertility. Some couples have trouble getting pregnant because of semen, the fluid that contains sperm. A test called semen analysis checks for problems with the amount, size, shape or movement of sperm. Semen analysis checks for these issues. IUI can overcome some of these issues. That's because preparing sperm for the procedure helps separate higher quality sperm from those of lower quality.
• Cervical factor infertility. Problems with the cervix can cause infertility. The cervix is the narrow, lower end of the uterus. It provides the opening between the vagina and uterus. The cervix makes mucus around the time the ovary releases an egg, also called ovulation. The mucus helps sperm travel from the vagina to either fallopian tube, where the egg awaits. But if cervical mucus is too thick, it may impede the sperm's journey. The cervix itself also may prevent sperm from reaching the egg. Scarring, such as that caused by a biopsy or other procedures, can cause the cervix to thicken. IUI bypasses the cervix to make pregnancy more likely. It places sperm directly into the uterus and increases the number of sperm available to meet the egg.
• Ovulatory factor infertility. IUI also may be done for people who have infertility caused by problems with ovulation. These issues include a lack of ovulation or a reduced number of eggs.
• Semen allergy. Rarely, an allergy to proteins in semen can cause a reaction. When the penis releases semen into the vagina, it causes a burning feeling and swelling where the semen touches the skin. A condom can protect you from the symptoms, but it also prevents pregnancy. IUI can allow for pregnancy and prevent the painful symptoms of the allergy. That's because many of the proteins in semen are removed before the sperm is inserted.

Often, intrauterine insemination is a simple and safe procedure. The risk of it causing serious health problems is low. Risks include:

• Infection. There's a slight chance of infection after IUI.
• Spotting. During IUI, a thin tube called a catheter is placed through the vagina and into the uterus. Then sperm are injected through the tube. Sometimes, the process of placing the catheter causes a small amount of vaginal bleeding, called spotting. This doesn't usually have an effect on the chance of pregnancy.
• Multiple pregnancy. IUI itself isn't linked with a higher risk of becoming pregnant with twins, triplets or more babies. But when fertility medicines are used along with it, the chance of this happening goes up. A multiple pregnancy has higher risks than a single pregnancy does, including early labor and low birth weight.

Intrauterine insemination involves some key steps before the actual procedure:

• Watching for ovulation. Because the timing of IUI is key, checking for signs that the body might ovulate is crucial. To do this, you might use an at-home urine ovulation predictor kit. It detects when your body produces a surge or release of luteinizing hormone (LH), which causes the ovary to release an egg. Or you might have a test done that makes images of your ovaries and egg growth, called transvaginal ultrasound. You also may be given a shot of human chorionic gonadotropin (HCG) or other medicines to make you ovulate one or more eggs at the right time.
• Timing the procedure right. Most IUIs are done a day or two after tests show signs of ovulation. Your doctor will likely have a plan spelled out for the timing of your procedure and what to expect.
• Preparing the semen sample. Your partner provides a semen sample at the doctor's office. Or a vial of frozen donor sperm can be thawed and prepared. The sample is washed in a way that separates the highly active, healthy sperm from lower-quality sperm. Washing also removes elements that could cause reactions, such as serious cramps, if placed in the uterus. The likelihood of becoming pregnant rises by using a small, highly concentrated sample of healthy sperm.

Wait two weeks before taking an at-home pregnancy test. Testing too soon could produce a result that is:

• False-negative. The test finds no sign of pregnancy when, in fact, you really are pregnant. You might get a false-negative result if pregnancy hormones aren't yet at levels that can be measured.
• False-positive. The test detects a sign of pregnancy when you really aren't pregnant. You might get a false-positive if you took fertility medicines such as HCG and the medicine is still in your system.

You may have a follow up visit about two weeks after your home pregnancy test results. At the appointment you may get a blood test, which is better at detecting pregnancy hormones after sperm fertilize an egg.

If you don't become pregnant, you might try IUI again before you move on to other fertility treatments. Often, the same therapy is used for 3 to 6 cycles of treatment to maximize chances of pregnancy.