Summary for Variable Group: First method use
Variables in this group describe the timing of the respondent's first use of contraception - the age she first used a method, the date she first used a method, and whether the first method use was before or after first sex. Variables also record which method was the first method (cervical cap, condoms, diaphragm, female condom, foam, injectables, the IUD, jellies, creams, or suppositories, the morning after pill, Norplant, the patch, the Pill, the rhythm method, the sponge, withdrawal, partner's vasectomy, female sterilization, or some other method) and whether multiple methods were used at first method use. In addition, a summary variable is available (IFSS_TYPALLFM) that has a value of 1 if any first method was recorded and missing otherwise.
Summary for Variable Group: Contraceptive history
This variable group provides information on the respondent's knowledge of how various contraceptive methods are used to prevent pregnancy, whether she has ever used any contraceptive method, whether she has ever used particular methods, the method(s) she used at her first sex, the method(s) she used at her last sex, the method(s) she is currently using, and where she obtained her current method(s). It also includes information on whether the respondent has ever taken birth control pills for medical reasons, what type of pill she has used most recently, and her frequency of intercourse over the last month. More complete measures of contraceptive use history are located in the contraceptive calendar.
Age at first birth control method use
|IFSS_AGEFSUS records R's age when she first used a contraceptive method.
General Comparability Notes
Summary: IFSS_AGEFSTUS is largely comparable across surveys. In the 1988 NSFG, IFSS_AGEFSTUS is calculated based on the month and year of first method use, while in the other surveys IFSS_AGEFSTUS is taken directly from questions about age at first use. There are some differences in question universe across surveys.
In the 2002 and 1995 National Surveys of Family Growth, all respondents who had ever used a contraceptive method were first asked whether the first time they used a method was before the first time they had sex, at the same time, or after their first sex. For respondents whose first use was when they first had sex, IFSS_AGEFSTUS is taken from a question about how old the respondent was when she first had sex. Respondents whose first use was before or after their first sexual intercourse were asked how old they were when they first used a method. This information is recorded in IFSS_AGEFSTUS.
In the 1988 NSFG, respondents were only asked their age at first method use if they reported that they did not know the month and year of first method use. For respondents who did know the month and year of first use, IFSS_AGEFSTUS is calculated from that variable, IFSS_CMFIRSM, combined with the month and year the respondent was born. Some women did not know the exact month of first method use, but reported the season they first used a method. To create IFSS_CMFIRSM for these women, a random month was imputed within the three-month window implied by the season.
IFSS_AGEFSTUS is defined for all women who have ever used a contraceptive method for any reason. IFSS_AGEFSTUS takes on values of not ascertained, refused, or don't know for women who cannot report their age at first method use and for women who report first method use at first sex but cannot report their age at first sex. Not ascertained, refused and don't know responses are imputed and flagged accordingly.
Separate variables exist for age at first method use (IFSS_AGEFSTUS) and date of first method use (IFSS_CMFIRSM). Respondents were asked for this information separately in the 1995 and 2002 NSFGs, and responses may not be consistent. In 2002, some women report ages of first method use less than 5. These are highly suspect and have been flagged with IFSS_AGEFSTUS_I=-1.
Imputation Flag Exists
|Imputation Flag Values|
|1||Imputed in original study|
|3||Month imputed (Original file edit)|
|4||Age known, month imputed|
|5||Originally imputed as June, recoded to random month|
|7||Multiple regression imputed: Not ascertained|
|8||Multiple regression imputed: Refused|
|9||Multiple regression imputed: Don't know|
|10||Midpoint of a given range|
|11||Answer comes from a follow-up question|
|12||Midpoint of a range given as a follow-up|
|13||Answer is rounded up|
|14||Answer is rounded down|
|15||Reported months and weeks, weeks<=4|
|17||Reported months=weeks & weeks>4|
|18||Reported months!=trunc(weeks/4.35), months!=weeks, weeks>4|
|19||Months coded NA/RF/DK|
|20||Weeks coded NA/RF/DK|
|21||Impossible to determine which method used last|