Comparative study on intermittent versus continuous use of a contraceptive pill administered by vaginal route

Contraception. 1995 Jun;51(6):355-8. doi: 10.1016/0010-7824(95)00101-f.


A multicenter, international, randomized, comparative trial was conducted to assess the acceptability, efficacy and safety of two different schedules of a contraceptive pill, containing 250 micrograms levonorgestrel and 50 micrograms ethinyl estradiol, administered by the vaginal route. One schedule of daily administration for 21 days with a seven-day interruption to allow withdrawal bleeding was compared to daily administration without interruption for bleeding. A total of 900 women were recruited in three countries, Brazil, Egypt and China; 7,090 women-months of vaginal pill use were recorded (3,364 using the pills intermittently and 3,726 continuously). Four undesired pregnancies occurred, one in Egypt and three in China, all four in women using the pills intermittently. There was a statistically significant difference (p = 0.486) in pregnancy rate between the two groups. There were no other significant differences in discontinuation rates despite marked differences in bleeding patterns, amenorrhea predominating in the continuous use group. Hemoglobin levels increased significantly in the two groups but hematocrit was significantly higher in the continuous use group.

PIP: 900 healthy women 16-42 years old were recruited in Brazil, China, and Egypt for a multicenter, randomized, comparative clinical trial to determine the acceptability, efficacy, and safety of two different schedules of a contraceptive pill with 250 mcg levonorgestrel and 50 mcg ethinyl estradiol administered vaginally. The two schedules were: 1) daily vaginal use of the pill for 21 days, followed by withdrawal for regular bleeding, and restarted 7 days later, and 2) use of the pill by the vaginal route nonstop for one year. There were no significant difference in cumulative discontinuation rates between the two groups (total, 15.5 for intermittent group and 14.64 for continuous group), except for unwanted pregnancy. The only unwanted pregnancies occurred to 4 women in the intermittent group (1.04%) (p = 0.0486). Women in the continuous use group were more likely than those in the intermittent group to have spotting at least once (20.6% vs. 4.4%; p 0.001). Women in the continuous group were more likely than those in the intermittent group to have amenorrhea. For example, the mean number of bleeding/spotting days during all time intervals was lower for the continuous group than for the intermittent group (p 0.001; last interval, 0.97 vs. 12.83). Hemoglobin levels increased considerably in both groups between baseline and one year of use (11.61 vs. 11.9 g/dl for intermittent group and 11.54 vs. 11.81 g/dl for continuous use; p 0.001). The mean value of hematocrit at 12 months for the continuous group was higher than that at baseline (38.8% vs. 38.2%; p = 0.011). It did not increase in the intermittent group, however. Women in both groups gained weight during the 12 months of pill use. The weight gain was significant for the continuous group only. These findings suggest that continuous use of vaginal contraceptive pills may be more advantageous than intermittent use oral contraceptives and may benefit anemic women and those who bleed heavily during menstruation.

Publication types

  • Clinical Trial
  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Intravaginal
  • Adolescent
  • Adult
  • Brazil
  • China
  • Contraceptive Agents, Female / administration & dosage*
  • Contraceptive Agents, Female / adverse effects
  • Contraceptive Agents, Female / standards
  • Dosage Forms
  • Dose-Response Relationship, Drug
  • Drug Combinations
  • Egypt
  • Erythrocyte Count
  • Estradiol Congeners / administration & dosage*
  • Estradiol Congeners / adverse effects
  • Estradiol Congeners / standards
  • Ethinyl Estradiol / administration & dosage*
  • Ethinyl Estradiol / adverse effects
  • Ethinyl Estradiol / standards
  • Female
  • Hematocrit
  • Hemoglobins / analysis
  • Humans
  • International Cooperation
  • Levonorgestrel / administration & dosage*
  • Levonorgestrel / adverse effects
  • Levonorgestrel / standards
  • Time Factors


  • Contraceptive Agents, Female
  • Dosage Forms
  • Drug Combinations
  • Estradiol Congeners
  • Hemoglobins
  • Ethinyl Estradiol
  • Levonorgestrel