Women aged 25 years and younger are more likely to stop using birth control than women over 25 years of age. They are also more likely to get pregnant while using birth control compared with older women. We do not know which birth control methods have the lowest pregnancy rates and the highest continued use in young women.
We searched for randomized trials of birth control methods until August 2015. Randomized trials are clinical studies in which people are randomly put into one of two or more treatment groups. Women in these studies were 25 years old or younger. The birth control methods could be either hormonal or a non-hormonal device placed in the uterus. The hormonal methods included pills, vaginal rings, or implants. The methods that are placed in the uterus include the intrauterine device (IUD) without hormones and the intrauterine system that has the hormone levonorgestrel (LNG-IUS). IUDs and the LNG-IUS are sometimes called intrauterine contraception (IUC).
Key results and quality of the evidence
We found five trials that enrolled had a total of 1503 women. Some studies looked at different types of IUC, while others compared pills versus a vaginal ring, skin patch, or IUC. No study showed any major difference between the groups in pregnancy or continued use. Some of the trials were too small to find a difference. Women kept using IUC at least as long as pills in one study. IUC may be useful for women in this age group. Studies of different birth control with more women would help determine which methods work the best for young women. Overall, the quality of the results was moderate to low.
We considered the overall quality of evidence to be moderate to low. Limitations were due to trial design or limited reporting. Different doses in the LNG-IUS did not appear to influence efficacy over three years. In another study, continuation of the LNG-IUS appeared at least as high as that for the COC. The current evidence was insufficient to compare efficacy and continuation rates for hormonal and intrauterine contraceptive methods in women aged 25 years and younger.
Women between the ages of 15 and 24 years have high rates of unintended pregnancy; over half of women in this age group want to avoid pregnancy. However, women under age 25 years have higher typical contraceptive failure rates within the first 12 months of use than older women. High discontinuation rates may also be a problem in this population. Concern that adolescents and young women will not find hormonal or intrauterine contraceptives acceptable or effective might deter healthcare providers from recommending these contraceptive methods.
To compare the contraceptive failure (pregnancy) rates and to examine the continuation rates for hormonal and intrauterine contraception among young women aged 25 years and younger.
We searched until 4 August 2015 for randomized controlled trials (RCTs) that compared hormonal or intrauterine methods of contraception in women aged 25 years and younger. Computerized databases included the Cochrane Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, POPLINE, CINAHL, and LILACS. We also searched for current trials via ClinicalTrials.gov and the International Clinical Trials Registry Platform (ICTRP).
We considered RCTs in any language that reported the contraceptive failure rates for hormonal or intrauterine contraceptive methods, when compared with another contraceptive method, for women aged 25 years and younger. The other contraceptive method could have been another intrauterine contraceptive, another hormonal contraceptive or different dose of the same method, or a non-hormonal contraceptive. Treatment duration must have been at least three months. Eligible trials had to include the primary outcome of contraceptive failure rate (pregnancy). The secondary outcome was contraceptive continuation rate.
One author conducted the primary data extraction and entered the information into Review Manager. Another author performed an independent data extraction and verified the initial entry. For dichotomous outcomes, we computed the Mantel-Haenszel odds ratio (OR) with 95% confidence interval (CI). Because of disparate interventions and outcome measures, we did not conduct meta-analysis.
Five trials met the inclusion criteria. The studies included a total of 1503 women, with a mean of 301 participants. The trials compared the following contraceptives: combined oral contraceptive (COC) versus transdermal contraceptive patch, vaginal contraceptive ring, or levonorgestrel intrauterine system 20 µg/day (LNG-IUS 20); LNG-IUS 12 µg/day (LNG-IUS 12) versus LNG-IUS 16 µg/day (LNG-IUS 16); and LNG-IUS 20 versus the copper T380A intrauterine device (IUD). In the trials comparing two different types of methods, the study arms did not differ significantly for contraceptive efficacy or continuation. The sample sizes were small for two of those studies. The only significant outcome was that a COC group had a higher proportion of women who discontinued for 'other personal reasons' compared with the group assigned to the LNG-IUS 20 (OR 0.27, 95% CI 0.09 to 0.85), which may have little clinic relevance. The trial comparing LNG-IUS 12 versus LNG-IUS 16 showed similar efficacy over one and three years. In three trials that examined different LNG-IUS, continuation was at least 75% at 6 to 36 months.