Stevens-Simon C, Kelly L, Singer D
Department of Pediatrics, University of Colorado Health Science Center, Denver, USA.
Fam Plann Perspect. 1999 Mar-Apr;31(2):88-93.
Even in intensive, adolescent-oriented programs, in which access to highly effective contraceptives is guaranteed, repeat adolescent pregnancies commonly occur.
To assess whether adoption of the contraceptive implant would lower the rate of repeat pregnancy, contraceptive use and pregnancy outcomes were tracked among 309 adolescent mothers--171 "early" implant users who began use within six months of delivery and 138 who either adopted another method or had used no method. Participants were interviewed at delivery and at six-month intervals through the second year postpartum. Multivariate logistic regression analyses were conducted to ascertain the likelihood of a repeat pregnancy within the first and second year postpartum.
During the first year postpartum, although 7% of the early implant users had their implants removed, pregnancy rates were significantly (p < .0001) lower among early implant users (less than 1%) than among the other adolescent mothers in the sample (20%). By the end of the second year postpartum, 37% of early implant users had discontinued use. Nevertheless, their two-year pregnancy rate (12%) remained significantly lower (p < .0001) than that of the other adolescent mothers (46%). The multivariate analysis showed that early implant use was the only independent predictor of a repeat pregnancy within the first year postpartum, while early use, parity and number of risk factors for repeat pregnancy were independently associated with the likelihood of another pregnancy in the second year postpartum.
Although early implant insertion significantly decreased the rate of rapid, repeat adolescent pregnancies, the rates of removal and of pregnancy by the end of the second year postpartum were high. Thus, health care providers need to address the motivational components of adolescent pregnancy even among those who accept ostensibly long-term methods.
即使在以青少年为导向的强化项目中，能确保获得高效避孕药具，青少年再次怀孕的情况仍普遍发生。
为评估采用避孕植入物是否会降低再次怀孕率，对309名青少年母亲的避孕措施使用情况及妊娠结局进行了跟踪——171名“早期”植入物使用者在分娩后六个月内开始使用，138名采用了其他方法或未采取任何避孕措施。在分娩时及产后第二年每隔六个月对参与者进行访谈。进行多变量逻辑回归分析以确定产后第一年和第二年再次怀孕的可能性。
在产后第一年，尽管7%的早期植入物使用者取出了植入物，但早期植入物使用者的怀孕率（不到1%）显著低于样本中的其他青少年母亲（20%）（p < 0.0001）。到产后第二年年底，37%的早期植入物使用者停止使用。然而，她们的两年怀孕率（12%）仍显著低于其他青少年母亲（46%）（p < 0.0001）。多变量分析表明，早期使用植入物是产后第一年再次怀孕的唯一独立预测因素，而早期使用、产次和再次怀孕的风险因素数量与产后第二年再次怀孕的可能性独立相关。
尽管早期植入显著降低了青少年快速再次怀孕的比率，但产后第二年年底的取出率和怀孕率仍然很高。因此，医疗保健提供者需要关注青少年怀孕的动机因素，即使是那些接受表面上长期避孕方法的人。
