Nelson AL, Kaunitz AM, Kroll R, et al. - Researchers conducted this single-arm, open-label, multicenter, 1-year (13 cycle), phase 3 study examining the contraceptive efficacy, safety, and tolerability of a contraceptive transdermal delivery system, (TDS; TWIRLA) containing levonorgestrel (LNG) and ethinyl estradiol (EE). They enrolled 2,032 demographically diverse sexually active women ≥ 18 years old, who were at risk for pregnancy, irrespective of body mass index (BMI). Patches were used by women in 28-day cycles (3 consecutive administrations of 7-day patches followed by 7 days off-treatment/patch-free week). Findings support the effectiveness of the low-dose LNG/EE TDS in preventing pregnancy in a population of women representative of US demographics. Women with BMI ≥30 kg/m² showed reduced efficacy. The TDS safety and tolerability profile was comparable to those reported for other similar dose combined hormonal contraceptives. This phase 3 study yielded support to the US Food and Drug Administration approval of TWIRLA for prevention of pregnancy in women with BMI < 30 kg/m².