An intrauterine device (IUD) is a small plastic object that is placed inside the uterus by a physician, nurse, or midwife. How an IUD works to prevent pregnancy is not known for certain. In the United States, two types of IUDs are available. One type releases the female hormone progesterone and must be replaced every year. The other is made of copper and is effective for at least
In rare cases, contractions of the uterus during menstruation can expel an IUD. If you can feel your partner’s IUD with your penis during sexual intercourse, suggest that she see her doctor to check whether the IUD is being expelled.
Rhythm methods (also called fertility awareness or the ovulation method) depend on avoiding sexual intercourse within 4 days before egg release. Most women release an egg from an ovary about 14 days before the start of their men- strual cycle. The unfertilized egg survives for only 24 hours, but sperm can sur- vive for 2 to 7 days after intercourse, so fertilization may occur from intercourse that took place up to 7 days before release of the egg and 3 days after.
There are three variations of the rhythm method. In the temperature method, a woman determines her basal body temperature (her body temperature at rest) by taking her temperature before she gets out of bed each morning. This tempera- ture drops slightly (about 0.2 degree Fahrenheit) just before ovulation. A day or so after the drop, a distinct rise (about 0.6 to 0.8 degree Fahrenheit) signals the beginning of ovulation. The couple avoids unprotected intercourse from the time the woman’s temperature drops through the time it remains elevated for 3 con- secutive days. The problem with this approach is that other factors, such as ill- ness, can alter a woman’s body temperature.
In the mucus method, a woman observes the changes in the consistency of her cervical mucus. Its consistency changes from dry immediately after menstrua- tion to very slippery or watery shortly after an egg is released. The woman can have intercourse with a low risk of conception immediately after her menstrual period ends and up to the time she observes an increased amount of cervical mucus. When both the temperature and the mucus methods are used together, it is called the symptothermal method.
The calendar-rhythm method requires a woman to carefully keep track of her menstrual cycles over a year’s time. She then subtracts 18 days from the shortest and 11 days from the longest of the previous 12 menstrual cycles. For example, if a woman’s cycles last from 26 to 29 days, she must avoid intercourse from day 8 through day 18 of each cycle. This is the least reliable of the three rhythm methods. When it is used together with the symptothermal method, however, its effectiveness may reach the higher end of the estimated 53 to 86 percent range given for the rhythm methods. Note, however, that the low end of this range is lit- tle better than chance (50/50).