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Public Health Rep. 2010 Nov-Dec; 125(6): 913–915.
PMCID: PMC2966677

NCHS Dataline

The National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention (CDC) has released data from the National Survey of Family Growth (NSFG). The NSFG collects data on factors affecting the formation, growth, and dissolution of families, including marriage, divorce, and cohabitation; contraception; sterilization and infertility; pregnancy outcomes; and births. The NSFG was conducted periodically for several decades but became a continuous survey in 2006.

Data for 2006–2008 were collected through in-person interviews with 13,495 men and women 15–44 years of age in the U.S. household population. Interviews were conducted by female interviewers in the homes of people selected for the sample. Data from the 2006–2008 period have been released in a public-use data file; two new reports profile the use of contraceptive methods in America and patterns of teen sexual activity, contraceptive use, and childbearing. Another new report describes the survey design and analysis.

TRENDS IN CONTRACEPTIVE USE

A new report presents trend data from earlier cycles of the NSFG for 1982, 1995, 2002, and the latest published data for 2006–2008 on contraceptive use and method of choice.1 The contraception report is based on interviews with a representative sample of 7,356 women. Patterns of contraceptive use by age, marital status, race/ethnicity, educational status, childbearing history, and other characteristics are presented.

Contraceptive use is a major factor affecting birth and pregnancy rates as well as the rate of unintended pregnancy. Key findings in the report show that:

  • Virtually all (99% in 2006–2008) of sexually experienced women (defined as those having had intercourse at least once) had used some method of contraception. About 93% had ever had a partner use a condom, 82% of women had used the oral contraceptive pill (the pill), and 59% had had a partner who used withdrawal. About one in five women had used the three-month injectable. The percentage of women who had ever used emergency contraception at least once increased from 4% in 2002 to 10% in 2006–2008. Also during that period, the use of other new methods increased. By 2006–2008, the contraceptive patch had been used by 10% of women, and 10% of women had also used the contraceptive ring, which was first introduced in 2002. The NSFG data also showed a steep decline in the use of the diaphragm, which has virtually disappeared from use.
  • Oral contraceptives, used by 28% of women aged 15–44 years, was the most frequent primary method of contraception. The pill was followed by female sterilization, used by 27% of women. Other leading methods were the male condom (16%) and male sterilization (10%), with a smaller number of women using the intrauterine device and the three-month injectable. Women were allowed to report more than one form of current contraception (during the month of the interview), and the most effective method was considered the primary method.
  • Use of contraception at first premarital intercourse has increased, primarily due to increased use of the condom.
  • Contraceptive methods differed by demographic characteristics. College-educated women were much more likely than less educated women to use the pill and less likely to use female sterilization. There were also differences by race/ethnicity: female sterilization was used by 22% of black women, 20% of Hispanic women, and only 15% of white women. Male sterilization was used by 8% of the male partners of white women, 3% of the male partners of Hispanic women, and 12% of the male partners of black women.
  • Age plays a role in the selection of a contraceptive method. The proportion of women who were using contraception and chose female sterilization increased with age to 50% by 40–44 years of age. In contrast, the use of the pill declined steadily with age—more than half of women aged 15–19 years used an oral contraceptive compared with 11% of women aged 40–44 years. The typical or most common patterns of contraception use in the U.S. were to use the condom at first intercourse, the pill to delay the first birth, and female sterilization when the woman has had all the children she wants.
  • Most women reported using only one method of contraception in any given month, but about 8% were using two or more methods in 2006–2008.
  • Women also reported whether they had stopped using a method of contraception because they were dissatisfied with it. About 30% had stopped using the pill, 43% had discontinued the three-month injectable, and 50% had stopping using the contraceptive patch.

The report includes international comparisons showing that a much higher percentage of women are using the pill in other countries, and in some countries the proportion of couples relying on the male condom was about twice that of the U.S. The report also examined the risk of unintended pregnancy by women who were having intercourse and not using a method of contraception. The report is available on the NCHS website at http://www.cdc.gov/nchs.

TEENAGERS' PATTERNS OF SEXUAL ACTIVITY, CONTRACEPTION, AND CHILDBEARING

A new report on U.S. teenagers, “Teenagers in the United States: Sexual Activity, Contraception, and Childbearing, National Survey of Family Growth 2006–2008,” presents the latest data from the survey and, for some indicators, includes trend data from earlier cycles of the survey.2 In 2006–2008, about 42% of never-married women and 43% of never-married men aged 15–19 years had had sexual intercourse at least once. This level of sexual activity had not changed significantly from the results of the 2002 NSFG. For both male and females, however, the percentage of sexually active teenagers had declined from previous surveys, from 51% for females in 1988 to 42% in 2006–2008, and from 55% for males in 1995 to 43% in 2006–2008. Among never-married teenagers in 2006–2008, 79% of females and 87% of males used a method of contraception at first sex.

Other highlights from the report showed substantial differences in patterns of teen sex and childbearing by characteristics of teenagers and their families. Both female and male teenagers whose mothers had had their first birth as a teen were more likely to be sexually experienced than those whose mothers had had their first birth at age 20 years or older. Teenagers who did not live with both parents at 14 years of age were also more likely to be sexually experienced than those who were living with their parents at that age.

Teenagers' most common first sexual partners were those with whom they were “going steady” as opposed to someone in a less involved relationship. The second most common relationship with the first sexual partner was having just met, and this type of relationship was more common among male teenagers. The vast majority of never-married teenagers had had no intercourse in the month before the interview, but 12% of female teens and 10% of male teens had had sex four or more times in the month before the interview. The condom was the most commonly used method among sexually experienced female teens (95%) followed by withdrawal (58%) and the pill (55%). Among never-married sexually experienced female teens, 79% used a contraceptive method at first intercourse, 68% used a condom, and 15% used the pill. There was no statistically significant difference in contraceptive use at first intercourse for female teens between 2002 and 2006–2008. However, for males a significantly higher percentage used the condom in 2006–2008 (81%) compared with 2002 (71%), although there was no change in the use of any method.

NSFG data provide information to help interpret the information obtained from birth certificates reported through the National Vital Statistics System. After a long period of decline in teen birth rates from a peak in 1991, the teen birth rate increased between 2005 and 2007, but dropped 2% according to preliminary data for 2008. The overwhelming majority of teen births were unintended. Information on patterns of sexual activity and contraceptive use can be analyzed along with teen birth rates to better understand these trends.

DESIGN OF THE CONTINUOUS NSFG

Published to coincide with the first release of data from the continuous NSFG, “The 2006–2010 National Survey of Family Growth: Sample Design and Analysis of a Continuous Survey”3 provides a wide range of useful information to data users as they begin their analyses of survey findings. The report describes the procedures used to select the sample, develop the sampling weights, impute missing data, and estimate sampling errors. Analysis of NSFG data requires the use of sampling weights and estimation of sampling errors that account for the survey's complex sample design and estimation features. Sampling weights are provided on the data files. The rate of missing data in the survey is generally low. However, missing data were imputed for about 600 key variables that were used for most survey analyses. A multiple regression procedure using software called IVE-ware was used for imputation and is described in the report, which is available on the NCHS website at http://www.cdc.gov/nchs.

NSFG PUBLIC-USE FILES NOW AVAILABLE

The 2006–2008 NSFG public-use files have been released. ASCII data files, program (setup) files, a user's guide, codebook documentation, and questionnaires are all available on the NSFG website's main page atwww.cdc.gov/nchs/nsfg.htm. To communicate with NSFG staff and other users and to learn about new releases or announcements about the data files, users can sign up for the NSFG listserv at http://www.cdc.gov/nchs/products/nchs_listservs.htm.

Footnotes

NCHS Dataline was prepared by Sandra S. Smith, MPH, Communications Consultant at the National Center for Health Statistics, Centers for Disease Control and Prevention.

References

1. Mosher WD, Jones J. Use of contraception in the United States: 1982–2008. Vital Health Stat Series. 2010;23(29) [PubMed]
2. Abma JC, Martinez GM, Copen CE. Teenagers in the United States: sexual activity, contraceptive use, and childbearing, National Survey of Family Growth 2006–2008. Vital Health Stat Series. 2010;23(30) [PubMed]
3. Lepkowski JM, Mosher WD, Davis KE, Groves RM, Van Hoewyk J. The 2006–2010 National Survey of Family Growth: sample design and analysis of a continuous survey. Vital Health Stat Series. 2010;2(150) [PubMed]

Articles from Public Health Reports are provided here courtesy of SAGE Publications