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