Objective
The purpose of this study was to characterize age-group specific patterns in the stability of contraceptive use and to evaluate whether factors that are associated with nonuse and sporadic use, compared with stable use, differ by age among women who are at risk for unintended pregnancy.
Study Design
We used data from the 2006-2010 National Survey of Family Growth to characterize the prevalence of stable and sporadic contraceptive use and nonuse by age over a 1-year period. We used polytomous logistic regression models to assess the odds of contraceptive nonuse and sporadic use vs stable use. Age-stratified models were used to show age-group differences in associated characteristics.
Results
Over a 1-year period, stable contraceptive use decreased across age groups from 80% for teens 15-19 years old to 74% for women 20-24 years old, and 70-71% for women 25-34 and 35-44 years old. Contraceptive nonuse increased across age groups from 5% for teens 15-19 years old to 9-20% for older women. By contrast, sporadic use was least common for women 35-44 years old (10% compared with 16-17% for younger women). Among teens 15-19 years old, a history of method discontinuation because of dissatisfaction was associated with nonuse. Among older women, intentions to have children in the future and reported difficulty achieving pregnancy were associated with nonuse and sporadic use.
Conclusion
Because the stability of contraceptive use and associated factors differ by age, providers may need to consider these differences when talking to women about contraception. To address nonuse, helping teens identify a method that they are comfortable using may be especially important; for older women, discussing the potential for continuing fertility may be more important. To address sporadic use, discussing the benefits of user-independent methods may be helpful, with a particular emphasis on long-acting reversible contraceptives for younger women and teens who are less likely to have completed their desired childbearing and who have tended to rely on methods that are more difficult to use consistently.
Recent estimates for the United States indicate that 51% of all pregnancies are unintended. Unintended pregnancy rates are highest for women 18-24 years old, and public concern has focused on teens. However, among older women, the proportion of pregnancies that are unintended and the ratio of pregnancies that end in abortion vs live birth remains high. Similarly, although the consequences of unintended pregnancy for teens have received substantial attention, negative health outcomes are also more likely for older women and their children. The prevention of unintended pregnancy should be a public health priority for women of all ages.
Only 5% of unintended pregnancies are due to contraceptive failure; the remaining 95% occur among women who did not use any contraception, who experienced gaps in use of contraception, or who used contraception incorrectly or inconsistently. However, age differences in contraceptive use patterns have not been well explored. Only a few studies have tracked contraceptive use over time to differentiate between nonuse and gaps in use or examined whether the factors that are associated with incorrect or inconsistent use and nonuse differ by age. Understanding these differences is important; addressing the reasons for gaps in use, nonuse, and inconsistent or incorrect use may require different strategies, and the most significant barriers to contraceptive use may change over time with women’s contraceptive preferences, relationships, and reproductive intentions.
The objectives of this analysis were to (1) characterize the age-group specific prevalence of contraceptive nonuse and sporadic use as compared with stable use among women at risk for unintended pregnancy over a 1-year period and (2) evaluate whether the associations between particular characteristics and contraceptive nonuse or sporadic differ by age.
Materials and Methods
We used data from the 2006-2010 National Survey of Family Growth (NSFG). The NSFG uses a stratified, multistage probability sample of women and men 15-44 years old to create nationally representative estimates of sexual behavior and contraceptive use in the United States. For women, the final sample included 12,279 interviews, with a 78% response rate.
We defined months at risk for unintended pregnancy for the 12 months before each woman’s interview using the retrospective calendar data on sexual activity and contraceptive use. We considered a woman to be at risk during any month she had intercourse, unless she was pregnant or seeking pregnancy, was sterile, or had a partner who was sterile (by any means, including a tubal sterilizing operation or a vasectomy). Of the 12,279 women who were interviewed, 4821 women were excluded because they were not at risk during any month. An additional 72 women were excluded because of missing calendar data, for a final sample of 7386 women.
Our outcome of interest was the stability of contraceptive use over the past 12 months. Contraceptive ‘nonusers’ were women who did not use contraception during any month in which they were at risk. ‘Sporadic users’ were women who used contraception during some but not other at-risk months and women who used contraception at some point during every at-risk month but not the last time they had intercourse, if this occurred during an at-risk month. ‘Stable users’ were women who used contraception at some point during every at-risk month and the last time they had intercourse, if this occurred during an at-risk month.
The primary characteristic of interest in our analysis was age (15-19, 20-24, 25-34, or 35-44 years old). We also included characteristics that we considered likely to influence contraceptive use to evaluate whether the associations between these variables and patterns of use differed by age. The characteristics that we selected had been found previously to be associated with contraceptive use and were related to method dissatisfaction (history of ever discontinuing a method because of dissatisfaction), access to contraceptive services (health insurance coverage and receipt of birth control services in the past year), relationship stability and predictability of intercourse (number of partners in the past year, periods of sexual inactivity in the past year, and marital status), future childbearing intentions (intends to have children in the future), and reported difficulty achieving pregnancy. Additional control variables included parity, household income, education, and race/ethnicity.
We used NSFG sample weights to calculate the age-group specific prevalence of each characteristic in our analysis and the age-group specific prevalence of nonuse, sporadic use, and stable use. We used chi-squared tests with an adjusted Wald-F statistic to detect age differences. We constructed multivariable polytomous logistic regression models to assess the adjusted odds of nonuse vs stable use and sporadic use vs stable use, comparing women 15-19, 20-24, and 35-44 years old with those 25-34 years old. Because very few women had not ever used a contraceptive method in their lives, we excluded these women from regression analyses to allow our models to include a variable for ever having discontinued a method because of dissatisfaction. In addition, because very few women were uncertain whether they wanted to have children in the future, for our regression analyses, we placed these women in the same category as women who did not want to have children in the future and then compared them with women who did want to have children in the future. Based on univariable associations, findings from previous literature, and the absence of multicollinearity, we retained our full set of covariates. To assess whether the association between particular characteristics and patterns of contraceptive use differed by age, we constructed a multivariable model for each characteristic that we considered likely to influence contraceptive use in which we added an interaction term for age and that characteristic. To further evaluate characteristics with interaction terms that reached a significance level of a probability value of < .15, we constructed a series of age-stratified models. All analyses were conducted with SAS callable SUDAAN software (version 9.3; SAS Institute Inc, Cary, NC), which accounts for the complex sample and design variables of the NSFG to produce unbiased standard errors.
This study was reviewed by an Institutional Review Board of the Centers for Disease Control and Prevention and was determined to be research that did not involve human subjects.
Results
The prevalence of characteristics that we considered likely to influence contraceptive use and other demographic variables differed significantly by age ( Table 1 ). Teens 15-19 years old had the lowest prevalence of having ever discontinued a method because of dissatisfaction and having no health insurance in the past year. Women in the 2 oldest age groups had the highest prevalence of private health insurance but the lowest prevalence of having received birth control services in the past year. The prevalence of having only 1 partner in the past year, being married, and experiencing few months (0-2) of sexual inactivity in the past year increased across age groups from younger to older women. Intentions to have children in the future decreased across age groups. Reported difficulty achieving pregnancy increased across age groups.
| Characteristic | Years old, n b (% c ) | |||
|---|---|---|---|---|
| 15-19 (n = 962) | 20-24 (n = 1678) | 25-34 (n = 3134) | 35-44 (n = 1612) | |
| Method discontinuation because of dissatisfaction d | ||||
| Never used a method | — e | 10 (0.8) | 23 (0.7) | 28 (1.2) |
| Never discontinued because of dissatisfaction | 653 (69.7) | 885 (51.9) | 1468 (47.8) | 787 (50.9) |
| Ever discontinued because of dissatisfaction | 306 (30.0) | 783 (47.3) | 1642 (51.6) | 797 (47.9) |
| Health insurance coverage in the past year d | ||||
| Private | 479 (55.7) | 872 (58.6) | 1896 (67.1) | 1164 (76.1) |
| Public | 388 (37.8) | 526 (23.5) | 713 (18.2) | 203 (9.4) |
| None | 71 (6.6) | 279 (17.9) | 522 (14.7) | 243 (14.5) |
| Receipt of birth control services in the past year d,f | ||||
| Yes | 623 (65.8) | 1095 (65.5) | 1842 (58.4) | 691 (44.8) |
| No | 339 (34.2) | 583 (34.5) | 1292 (41.6) | 921 (55.2) |
| Number of partners in the past year d | ||||
| 1 | 628 (64.4) | 1230 (75.7) | 2655 (88.9) | 1444 (94.3) |
| ≥2 | 325 (35.6) | 428 (24.3) | 446 (11.1) | 142 (5.7) |
| Months without intercourse in the past year d | ||||
| 0-2 | 372 (37.2) | 1054 (65.1) | 2211 (75.8) | 1151 (75.6) |
| 3-5 | 184 (21.2) | 269 (14.6) | 406 (11.4) | 189 (10.2) |
| ≥6 | 406 (41.6) | 355 (20.2) | 517 (12.8) | 272 (14.2) |
| Marital status d | ||||
| Married | 28 (2.8) | 287 (21.3) | 1395 (54.6) | 952 (68.6) |
| Cohabiting | 119 (11.9) | 350 (22.1) | 509 (16.7) | 152 (7.5) |
| Single | 815 (85.3) | 1041 (56.6) | 1230 (28.6) | 508 (23.9) |
| Intends to have children in the future d | ||||
| Yes | 815 (86.6) | 1325 (80.4) | 1866 (62.1) | 381 (20.3) |
| Uncertain | 7 (0.4) | 13 (0.9) | 83 (2.6) | 43 (2.6) |
| No | 140 (13.0) | 340 (18.7) | 1185 (35.3) | 1188 (77.1) |
| Reports it is difficult or impossible to get pregnant d | ||||
| Yes | 26 (2.8) | 99 (5.1) | 235 (8.5) | 207 (12.0) |
| No | 936 (97.2) | 1569 (94.9) | 2852 (91.5) | 1344 (88.0) |
| Parity d | ||||
| 0 births | 793 (84.2) | 981 (65.9) | 1110 (38.4) | 418 (22.1) |
| 1 birth | 140 (12.6) | 419 (20.4) | 769 (25.0) | 418 (23.9) |
| ≥2 births | 29 (3.2) | 278 (13.6) | 1255 (36.6) | 776 (54.1) |
| Household income (% of FPL) d | ||||
| <100% | 362 (34.4) | 533 (26.6) | 761 (17.5) | 261 (13.4) |
| 100-400% | 505 (54.8) | 942 (59.4) | 1716 (56.1) | 922 (58.6) |
| ≥400% | 95 (10.9) | 203 (14.1) | 657 (26.4) | 429 (28.0) |
| Highest level of education d,g | ||||
| ≤12th grade | 203 (18.3) | 267 (13.9) | 467 (10.7) | 206 (10.8) |
| High school or equivalent | 299 (31.3) | 529 (29.6) | 774 (22.3) | 334 (20.7) |
| Some college or higher | 459 (50.4) | 882 (56.5) | 1893 (66.9) | 1072 (68.5) |
| Race/ethnicity h | ||||
| Hispanic | 210 (18.0) | 347 (16.8) | 778 (18.5) | 322 (14.5) |
| Non-Hispanic white | 472 (56.8) | 814 (59.3) | 1507 (60.6) | 857 (62.1) |
| Non-Hispanic black | 201 (15.6) | 381 (15.4) | 610 (13.3) | 289 (12.7) |
| Non-Hispanic other or multiple race | 79 (9.6) | 136 (8.5) | 239 (7.7) | 144 (10.7) |
a A woman was considered to be at risk for unintended pregnancy during any month that she had intercourse, unless she was pregnant or seeking pregnancy, she was sterile, or she had a partner who was sterile (by any means, including a tubal sterilizing operation or a vasectomy)
b Unweighted; totals for each characteristic may differ because of missing values
c Weighted; percentages for each characteristic may not sum to 100 because of rounding
d Significant at P < .001; χ 2 test based on adjusted Wald-F statistic
e Cells with dashes are not reported because of low cell counts (n < 5)
f Includes receiving a medical check-up related to using birth control, a birth control method or a prescription for birth control, and counseling or information about birth control, which includes emergency contraception and surgical sterilization
g Because women <20 years old have not had the opportunity to complete their education, other analyses have used the highest level of education obtained by a woman’s mother or mother figure for women 15-19 years old
h Significant at P < .05; χ 2 test based on adjusted Wald-F statistic.
Overall, 72% of the women were stable contraceptive users; 15% of the women were sporadic users, and 13% of the women were nonusers. Of the 1153 sporadic users, 160 women (14%) used contraception at some point during every at-risk month, but not at last intercourse. Stable contraceptive use decreased across age groups from 80% for teens 15-19 years old to 74% for women 20-24 years old and 70-71% for women 25-34 and 35-44 years old ( Table 2 ). Contraceptive nonuse increased across age groups from 5% for teens 15-19 years old to 9-20% for older women. By contrast, sporadic use was least common for women 35-44 years old (10%, compared with 16-17% for younger women). In multivariable models, the odds of nonuse vs stable use were decreased for women 15-19 and 20-24 years old vs 25-34 years old, whereas the odds of sporadic use vs stable use were decreased for women 35-44 vs 25-34 years old ( Table 2 ).
| Age group, y | Age-group specific percentage b of women by stability of contraceptive use, % (95% CI) | Adjusted odds (95% CI) c | |||
|---|---|---|---|---|---|
| Nonuse | Sporadic use | Stable use | Nonuse vs stable use | Sporadic use vs stable use | |
| 15-19 | 4.5 (3.2–6.3) | 15.9 (12.7–19.6) | 79.6 (75.5–83.1) | 0.34 (0.22–0.55) d | 1.28 (0.86–1.89) |
| 20-24 | 9.2 (7.2–11.7) | 16.4 (13.5–19.8) | 74.4 (70.7–77.7) | 0.65 (0.45–0.92) d | 1.16 (0.89–1.52) |
| 25-34 | 13.9 (12.1–15.9) | 16.5 (14.6–18.6) | 69.6 (66.9–72.1) | Reference | Reference |
| 35-44 | 19.6 (16.8–22.7) | 9.9 (7.9–12.4) | 70.5 (66.8–73.9) | 1.35 (0.99–1.83) | 0.61 (0.45–0.84) d |
a Among women who were at risk for unintended pregnancy and had ever used a contraceptive method. A woman was considered to be at risk for unintended pregnancy during any month that she had intercourse, unless she was pregnant or seeking pregnancy, she was sterile, or she had a partner who was sterile (by any means, including a tubal sterilizing operation or a vasectomy)
c Adjusted for health insurance coverage, receipt of birth control services, number of partners and months without insurance in the past year; marital status; intentions to have children in the future; reported difficulty achieving pregnancy; parity; household income; education; and race/ethnicity
In multivariable models that assessed whether the association between certain characteristics and contraceptive nonuse or sporadic use varied by age, we found a significant age-group by characteristic interaction for ever having discontinued a method because of dissatisfaction, health insurance in the past year, marital status, and intentions to have children in the future ( P < .05 for all interaction terms). Differences by age group did not reach significance for months of sexual inactivity in the past year, for reported difficulty achieving pregnancy ( P < .15), or for having multiple partners or receiving birth control services in the past year ( P > .5).
In age-stratified models, a history of ever having discontinued a method because of dissatisfaction was associated with increased odds of nonuse vs stable use among teens 15-19 years old, but not in any older age group ( Table 3 ). By contrast, the odds of nonuse were increased for women who intended to have children in the future among those in the 2 oldest age groups and for women who reported difficulty in achieving pregnancy among those in the 3 oldest groups. Having public vs private insurance was associated with increased odds of nonuse among women in the youngest and oldest age groups, but there was no change in the odds of nonuse for women without insurance vs private insurance in any age group. The odds of nonuse were reduced for single vs married women among those in the 2 middle age groups.
| Characteristic | Years old, adjusted odds ratio (95% confidence interval) b | |||
|---|---|---|---|---|
| 15-19 | 20-24 | 25-34 | 35-44 | |
| Method discontinuation because of dissatisfaction | ||||
| Never discontinued a method | Reference | Reference | Reference | Reference |
| Ever discontinued a method | 4.00 (1.31–12.2) c | 1.49 (0.81–2.76) | 0.85 (0.57–1.26) | 0.81 (0.48–1.38) |
| Health insurance coverage over the past year | ||||
| Private | Reference | Reference | Reference | Reference |
| Public | 7.89 (1.86–33.5) c | 2.68 (0.98–7.32) | 1.00 (0.56–1.81) | 6.18 (2.82–13.5) c |
| None | 3.48 (0.54–22.3) | 0.99 (0.37–2.68) | 0.86 (0.47–1.55) | 1.04 (0.50–2.15) |
| Months without intercourse in the past year | ||||
| 0-2 | Reference | Reference | Reference | Reference |
| 3-5 | 0.42 (0.14–1.30) | 0.69 (0.26–1.87) | 1.53 (0.86–2.75) | 0.97 (0.41–2.31) |
| ≥6 | 1.98 (0.74–5.29) | 1.99 (0.78–5.07) | 1.01 (0.52–1.95) | 1.24 (0.53–2.91) |
| Marital status | ||||
| Married | Reference | Reference | Reference | Reference |
| Cohabiting | 6.37 (0.90–45.3) | 0.78 (0.37–1.67) | 1.18 (0.72–1.94) | 0.88 (0.38–2.03) |
| Single | 2.18 (0.28–16.8) | 0.20 (0.08–0.46) c | 0.49 (0.26–0.91) c | 0.61 (0.29–1.29) |
| Intends to have children in the future | ||||
| Yes | 0.68 (0.22–2.12) | 1.21 (0.60–2.42) | 1.64 (1.09–2.49) c | 3.24 (1.87–5.60) c |
| No/uncertain | Reference | Reference | Reference | Reference |
| Reports that it is difficult or impossible to get pregnant | ||||
| Yes | 1.66 (0.42–6.50) | 4.20 (1.84–9.59) c | 9.65 (5.76–16.2) c | 13.4 (7.94–22.6) c |
| No | Reference | Reference | Reference | Reference |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
