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Contraceptive Use and Unintended Pregnancy
Abstract & Commentary
By Jeffrey T. Jensen, MD, MPH, Editor, Leon Speroff, Professor of Obstetrics and Gynecology, Vice Chair for Research, Oregon Health and Science University, Portland, is Editor for OB/GYN Clinical Alert.
Synopsis: In the most recent data from the National Survey of Family Growth, oral contraceptive pills remain the most widely used method of contraception, followed by female sterilization. Although more women are using highly effective methods like the IUD, the proportion at risk of unintended pregnancy and not using any method remains high at 7.3%.
Source: Mosher WD, Jones J. Use of Contraception in the United States: 1982-2008. Vital and Health Statistics. Hyattsville, MD: U.S. Department of Health and Human Services; May 2010: Publication No. PHS 2010-1350. Available at: www.cdc.gov/nchs/data/series/sr_23/sr23_029.pdf.
National estimates of contraceptive use and method choice from the most recent 2006-2008 cycle of the National Surveys of Family Growth (NSFG) were compared to earlier estimates based on the 1982, 1995, and 2002 surveys. These data are important, as contraceptive use is a major factor affecting birth and pregnancy rates, as well as the rate of unintended pregnancy. The NSFG is a nationally representative survey conducted by the National Center for Health Statistics. The 2006-2008 data were collected through in-person interviews with 13,495 men and women 15-44 years of age. The contraceptive report is based on the sample of 7356 women interviewed in 2006-2008. The response rate for women in the 2006-2008 survey was about 76%.
More than 99% of women 15-44 years of age who have ever had sexual intercourse with a male reported that they had used at least one contraceptive method. The typical pattern of contraceptive use in the United States is to use the condom at first intercourse, the pill to delay the first birth, and female sterilization at completion of childbearing.
The percentage of women whose male partner had ever used the condom increased from 52% to 93% from 1982 to 2006-2008. Ever use of emergency contraception has increased from less than 1% in 1995 to almost 10% in 2006-2008.
About 62% of the 61.9 million women aged 15-44 years were currently using contraception (at the date of interview) in 2006-2008. The other 38% were not using contraception for a variety of reasons. These included women who were "not at risk of unintended pregnancy" because they were currently pregnant or postpartum, trying to become pregnant, sterile for medical (noncontraceptive) reasons, unable to conceive, or had not had intercourse recently or ever. However, 7.3% of women were "at risk of unintended pregnancy" because they had been having intercourse in the last 3 months and were not using contraception.
Among current users of contraception, the leading method was the oral contraceptive pill, used by 10.7 million women; the second leading method was female sterilization, used by 10.3 million women. Between 2002 and 2006-2008, the proportion of IUD use increased from 2% to 5.5%. Age, parity, marital status, education, and income are closely related to the choice of method and the risk of unintended pregnancy.
With a population of almost 310 million,1 the United States has the fastest rate of population growth among more developed nations. Although much of this growth is fueled by immigration, even modest adjustments in the total fertility rate have profound consequences for population growth, environmental impact, and the world economy. A major factor affecting U.S. birth and pregnancy rates is the use and efficacy of contraception.
These initial results from the much-anticipated 2006-2008 NSFG provide important information on U.S. family planning trends. Established in 1973 by the National Center for Health Statistics (NCHS), the NSFG contributes a periodic survey of factors affecting the formation, growth, and dissolution of families, including contraception, sterilization, and sexual activity. Results of the NSFG are dependable and highly significant because they come from a rigorous nationally representative, multistage area, probability sample drawn from 120 areas across the country designed to produce national estimates. The NCHS has conducted the survey in 1973, 1976, 1982, 1988, 1995, 2002, and 2006-2008. Reports in 1973 and 1976 recorded information only for married or divorced women; in 1982 the survey was expanded to include women aged 15-44, regardless of marital status. Thus, trends regarding contraceptive use between the 1982, 1995, 2002, and current 2006-2008 reports are comparable.
In the 2006-2008 sample, current users of a contraceptive method represented about 62% of the sample, the same as in 2002, but a decline of 2.3% since 1995. This translates to an estimated 554,000 fewer contraceptive users. The good news is that there has been an increase in the use of more effective (hormonal and IUD) methods and an increased use of condoms at first intercourse since 1995. Although use of oral contraceptives dropped slightly, when numbers of vaginal ring users are considered, the overall use of combined hormonal methods remains around 19%. Use of male and female sterilization remained about the same (16.7% and 6.1%), but there were fewer users of depo-Provera (from 3.3% in 2002 to 2.0%) and more users of the IUD (1.3% to 3.4%).
The renaissance in IUD use is more impressive when use is evaluated as a proportion of contraceptive users (from 2.0% to 5.5%). Between 2002 and 2006-2008, IUD use dramatically increased among women with one (2% to 8%) or two (3% to 11%) children. One notable area where the 2006-2008 data appear to lag behind clinical practice is the low proportion of IUD use reported among nulliparous women (0.3%). The safety of the IUD in young and nulliparous women appears to be similar to that of older parous women.2 Since young nulliparous women experience the highest rates of unintended pregnancy and abortion,3 use of highly effective, long-acting, reversible methods like the IUD should be encouraged in this group.
Contraception use at first premarital intercourse is important because 94% of women aged 15-44 have had premarital intercourse.4 Teenagers who do not use a method have a higher risk of unintended pregnancy and sexually transmitted infection. While a growing proportion of the cohort experiencing first intercourse reported use of some method of contraception (84% between 2005-2008 compared to 76% in 2001-2004), this increase was due to equal growth in the use of condoms (from 64% to 72%) and withdrawal (3% to 9%), a method not associated with STI protection. Could this reflect the growing emphasis on abstinence education and away from sexuality and methods-based content during the last decade?
Another disturbing trend is the high proportion of women at risk for pregnancy that report non-use of contraception. This increased from 5.2% to 7.4% between 1995 and 2002, and remains at 7.3% in the current sample. Due to the large size of the NSFG sample, all these changes represent statistically significant differences; this 2.2% increase from 1995 to 2002 represents an additional 1.4 million women at risk of unintended pregnancy. This small increase is highly important because non-users of contraception contribute almost half of the total number of unintended pregnancies; about half of these are terminated by abortion. Perhaps not surprisingly, more than 44% of non-users cited "did not think they could get pregnant" as the reason for non-use. Seems to me that these numbers provide direct evidence of the lack of benefit (and probable harm) of the abstinence-only curriculum. Thank goodness the new administration sees this reality. Write your members of congress. Ending abstinence-only funding is an easy way to reduce federal spending!