Results
A total of 396 women participated in our survey. They were representative of urban/suburban women in general and of women of the practice [Table 1]. The average age of the respondents was 27 years; 98% (n=389) had sex with a man.
During their lifetimes these women used an aggregate total of 1421 methods of contraception (average=3.52±1.56 methods per woman; range=1-10). The methods used are listed in [Table 2]. All of the women (except the 5 who never had sex with a man) used 1 method of contraception at least once, 370 (93%) had used 2 methods, 287 (72%) had used 3, and 217 (55%) had used 4 or more. Eighty-one women (20%) reported having used more than 1 method at a time. Condoms were the most common first method of contraception (62%). The most common contraceptive methods used overall were OCPs (81%) and condoms (78%). Thirty-four percent had tried implantable or injectable hormonal contraception at least once. And 67 women (17%) had a tubal ligation (average age=28 years; range=21-45 years).
A total of 168 (42%) of the women became pregnant while using contraception, some more than once. Forty-nine women (13%) became pregnant twice and 13 women (3%) 3 times while using contraception. One hundred three women became pregnant while taking OCPs, 78 while using condoms and 11 while using an injectable contraceptive (depot medroxyprogesterone [DMP]). The women who became pregnant while using birth control were significantly more likely to be younger and African American. They were more likely to have a history of early initiation of birth control use, and they used more methods during their lifetimes. These women were pregnant more often and were more likely to use some type of public assistance [Table 3]. The total group of African American women in our survey was more likely to be younger, have some college education, and be single. Marital status did not correlate with becoming pregnant while using birth control; married, single, and separated or divorced women were equally represented. Women who became pregnant while using birth control were not more likely to use cigarettes, marijuana, or cocaine; have more partners; or start sexual relationships at an earlier age.
The rate of actual-use effectiveness of OCPs in this population was similar to the national average. First-year use effectiveness rates could not be determined, but lifetime effectiveness rates were estimated. Three hundred nineteen women (81%) had used OCPs for an aggregate total of 1422 years (average=4.5 years per woman; range=1 month-28 years). One hundred three women (33.3%) reported that they had become pregnant while using OCPs, some more than once. This was a pregnancy rate of 7.5%. Fifty-seven percent of the women who became pregnant while taking OCPs said they stopped using them because of getting pregnant.
Three hundred four women (78%) had used condoms for an aggregate total of 1178 years (average=3.9 years per woman; range=1 month-25 years). Seventy-eight women (25.6%) reported becoming pregnant while using condoms for a pregnancy rate of 6.6%. Fifty-five percent of those women stated that becoming pregnant was the reason for stopping condom use.
Eight-two women had used DMP for an aggregate total of 77.1 years with an average of 11 months per woman. Eleven women reported that they became pregnant while using DMP, for a pregnancy rate in our study of 14%.
Two major patterns of contraceptive use during a woman’s lifetime emerged. These 2 patterns described the contraceptive choices or directions of 82% of the women. One group of 210 women (53%), who will be called the “effective contraceptors,” started with condoms and then used OCPs or DMP. Following that change, they either continued to take OCPs or changed again to a method with a higher actual effectiveness rate (ie, DMP, Norplant [Wyeth-Ayerst; St. Davids, Penn] intrauterine device, tubal ligation, vasectomy, or hysterectomy).
The other group (the “less effective contraceptors,” n=110, 29%) also started with condoms. Forty-seven of these women changed immediately to a method less effective overall than OCPs (rhythm, withdrawal, gel/foam, diaphragm, or no method); 25 changed to use OCPs, and then began to use methods less effective than OCPs. Also included in this group were 38 women who began contraception by taking OCPs and then changed to less effective methods.
The effective contraceptors were significantly less likely to become pregnant while using birth control than the less effective contraceptors. Only 37% of the effective contraceptors became pregnant; 51% of the less effective contraceptors did so (odds ratio= 1.4; [Table 4]).
Discussion
Although there has been much research into the effectiveness, side effects, and reasons for discontinuation of individual birth control methods, the personal histories of how women have used contraception has seldom been examined. We attempted to document patterns of contraception use and to relate these patterns to unintended pregnancies.