There's been a lack of progress in preventing unintended pregnancies in the United States, Raquel D. Arias, MD, pointed out at her session “Contraception Update” at Internal Medicine 2013, held in San Francisco in April.
Dr. Arias, who is associate professor of clinical obstetrics and gynecology at the University of Southern California's Keck School of Medicine in Los Angeles, said that of the 6.7 million pregnancies in the U.S. each year, about one half are unintended, a statistic that hasn't really changed in the past decade. This rate puts the U.S. on a par with developing countries, she noted. Moreover, she said, the 10.7% of women who report not using contraceptives account for roughly half of all unintended pregnancies.
“You may wonder ‘Why were they not using anything?’ and the answer is that when asked, they said they didn't think they were at risk to get pregnant,” she said. This may be especially true of women at the beginning and end of their reproductive life, who often think that pregnancy isn't physically possible, she said.
Among the former group, unintended pregnancy rates are only going to become a greater problem, she said, because rising childhood obesity rates are leading to a younger age at menarche.
“The one thing you need to become mature at the hypothalamus-pituitary-adrenal axis is to weigh 98 pounds,” she said. “The average age at menarche [in the U.S.] in general is about 12. The average age is dropping in much of the country to as low as 8. To the degree that childhood obesity contributes to many medical problems, it also contributes to ... unintended pregnancy.”
There are many effective contraceptive options available, but when considering which to recommend, it's very important to focus on the failure rate with typical rather than perfect use, Dr. Arias stressed. “I want you to never use perfect-use rates again,” she said. “I do not want you to use them in your practice. I want you to use typical-use rates.”
As an example, Dr. Arias said many people, even physicians, still think the most effective form of reversible contraception is abstinence, but although its perfect-use failure rate is 0%, its typical-use failure rate in non-naïve users is estimated to be around 80%. “If abstinence applied to the FDA as a contraceptive, it would fail,” she said.
Female sterilization, IUDs, depot medroxyprogesterone acetate (DMPA, sold in the U.S. as Depo-Provera), and implants are considered the most effective methods of contraception with typical use, followed by oral contraceptives, the patch, the ring, and progestin-only pills. Condoms, spermicides, diaphragms, withdrawal and methods based on fertility awareness are generally considered less effective with typical use.
Oral contraceptives remain very popular in the U.S., Dr. Arias said, with more than 18 million current users. In fact, approximately 80% of all women use oral contraceptives at some point during their reproductive years, she noted. Although discontinuation rates are high, about 50% during the first year of use, the average duration of use is almost five years in those who continue past that point.
The drugs can be safely prescribed for women into their early fifties without other contraindications (for example, smoking), Dr. Arias said. The therapeutic goal, she noted, is to prescribe the lowest dose of hormones that prevents pregnancy and provides a side effect and cycle control profile that encourages long-term successful use.
One type of IUD, the levonorgestrel intrauterine system (LNG-IUS), sold in the U.S. under the brand name Mirena, is approved for five years' use and works as a barrier method. The cervical mucus is thickened, inhibiting sperm motility and function, as well as ovulation in some cycles, Dr. Arias said. There's also good evidence for noncontraceptive uses of the LNG-IUS, including treating heavy bleeding, reducing dysmenorrhea and pain, and providing endometrial protection during hormone therapy in perimenopausal and postmenopausal women. Use with tamoxifen is popular in other countries but is contraindicated in package inserts, she noted.
The copper IUD, meanwhile, is approved for 10 years' use and can also be used as an emergency contraceptive, Dr. Arias said.
“There is essentially no medical problem for which a copper IUD is contraindicated,” she said. “If that's the only thing you learn from this lecture, I will be happy.” She also noted that the copper IUD is as effective as a tubal ligation but very easily reversible. “A medical student could do it—with supervision, of course,” she said.
Among the other most effective options, etonogestrel implants last for three years and are immediately reversible, Dr. Arias said. She also noted that they are safe in patients in whom estrogen is contraindicated. One downside of implants is that bleeding patterns during use can be unpredictable, ranging from amenorrhea to spotting to frequent bleeding.
DMPA's side effects include unpredictable bleeding approaching amenorrhea with time and a slow return to fertility, which gets longer with advancing age. Dr. Arias noted that there is some concern about weight gain in patients using DMPA, but added, “If your patients starting [DMPA] do not increase their consumption or decrease their activity, they will be fine.”
She also noted that although DMPA has a black-box warning for more than two years of use due to decreases in bone mineral density, subsequent studies have shown that bone mineral density rebounds after use. DMPA is a good choice in women with sickle-cell anemia, those with seizure disorders, and, especially, women who are breastfeeding. “If you want to use something for a breastfeeding woman, this is what you use,” she stressed.
Progestin-only pills, on the other hand, are not a good choice for breastfeeding women because they need to be taken within a specific two-hour window every day, or a backup method is needed. Women with infants have so many other claims on their time, Dr. Arias said, that they can easily forget about birth control.
“You only have to have one woman trying her best to do a good job raising her child who has an unintended pregnancy while breastfeeding before you have to wonder whether progestin-only pills might not be the best method, even though they're an acceptable method, for women who are breastfeeding,” she said.
She also stressed that while many breastfeeding women think they can't get pregnant, that only applies for the first six months of exclusive breastfeeding. Once a baby begins taking any other form of nourishment, “you have to use something,” she said.
Dr. Arias also discussed emergency contraception, for which there are three options in the U.S.: progestin-only pills, progesterone-receptor antagonists, and the copper IUD. Progestin-only pills reduce the pregnancy rate by 85%, while progesterone-receptor antagonists delay ovulation for up to five days. The latter may be more effective in women with a BMI over 30 kg/m2.
The copper IUD can be inserted within seven days after unprotected intercourse and has the added benefit of offering 10 more years of highly effective contraception, Dr. Arias said. It's also the most effective form of emergency contraception, she noted, with a pregnancy rate of 0.2%.
Contraception is generally safe, Dr. Arias said, but certain contraceptives can exacerbate medical problems in some women. For example, she noted, oral contraceptives are an acceptable choice in a woman with polycystic ovary syndrome who has irregular menses, acne and hirsutism but should not be used in asymptomatic women with the factor V Leiden mutation.
If there's a question about your patient's specific circumstances, she recommended checking the medical eligibility criteria from the Centers for Disease Control and Prevention or the World Health Organization.
Use the available guidance to evaluate each individual case and decide what's best for your patient, Dr. Arias said. “Make the choice that's safer for her, safer for you, and safer for society.”