DMPA, Norplant starters have new backup data
DMPA, Norplant starters have new backup data
Does your medical protocol call for backup contraception for Norplant implants and depot medroxyprogesterone acetate (DMPA) injections when methods are initiated after the first seven days of the menstrual cycle? Two new studies examined cervical mucus changes caused by both progestin-only methods, with insight on the number of days needed for backup birth control when methods are initiated outside menses.1,2
Norplant implants and DMPA injections can be initiated safely any time providers are reasonably sure patients aren't pregnant. For that reason, many family planners schedule such first-start patients during menstruation. Implants and injections can be initiated outside menses; how ever, the length of time needed for backup contraception varies for those outside day seven of menses onset.
The Essentials of Contraceptive Technology (Johns Hopkins School of Public Health, Population Information Program, Baltimore), says no extra contraceptive protection is needed for first starts of Norplant or DMPA if the methods are begun during the first seven days of the menstrual cycle and the patient is still bleeding. But if a patient isn't bleeding or is starting on or after day eight of her menstrual period, she should use condoms or spermicide or avoid sex for 48 hours after insertion.3 An earlier Johns Hopkins publication recommends using backup protection for up to a week.4
Progestin-only methods thicken cervical mucus and lower sperm penetration. Progestin-only pills produce mucus changes within three to four hours of ingestion, while natural progesterone produces mucus changes somewhere within 24 to 48 hours.4 Few data have existed on the effect of Norplant and DMPA on cervical mucus within the first few hours and days of the two methods, which prompted the two studies.
Conducted in Santo Domingo, the Dominican Republic, and Baltimore, the Norplant study examined 42 first-time users between days eight and 13 of their cycles. Follow-up visits were held at six, 12, and 24 hours after insertion, then on days three and seven, for a sampling of cervical mucus and blood. In vitro mucus penetration tests were performed in the lab to measure how cervical mucus changes affected sperm penetration. Main outcome measures included cervical mucus scores, sperm penetration distances, and serum levels of progesterone, estradiol, and levonorgestrel.
The median cervical mucus score observed at baseline was rated at 6, indicating the mucus was somewhat hostile before insertion. Median scores declined to 5 at 12 and 24 hours and continued to decrease through day seven to a score of 2, deemed hostile to sperm. There was a substantial drop in the overall median distance the vanguard sperm travelled after 12 hours for each cervical mucus score grouping. Distance traveled decreased rapid ly between 12 and 24 hours, and by day three, 91% of the subjects had poor sperm penetration.
Those findings led the researchers to conclude that backup methods need not be used after day three post-insertion, says lead author Thomas Dunson, MS, who served as senior research associate at Family Health Interna tional in Research Triangle Park, NC, during the trial. "On the basis of our findings, deterioration of the quality of cervical mucus and sperm penetration is evident by 24 hours after insertion, although not to a level that would suggest adequate protection until 72 hours after insertion," the researchers state. "Therefore, we are confident in recommending that backup methods of contraception - e.g., condoms - need not be used for more than three days after insertion, even when the implants are inserted close to ovulation."
Women were recruited for the DMPA study at University of Campinas' family planning clinic in Brazil. Thirty women received the injection between days eight and 13 of their cycles, with the same visit protocol as in the Norplant study. Within 24 to 48 hours after administration, cervical mucus changes adverse to sperm penetration were noted. By day three, 97% of the women had mucus that would inhibit sperm penetration.
Norplant researchers concluded the deterioration in cervical mucus was severe enough at day three after implantation to indicate contraceptive efficacy. DMPA findings led to a more conservative approach. Sperm penetration declined after DMPA injection but remained maximal in one subject at day three. Based on that, the researchers say a backup method is needed for seven days when the first DMPA injection is given after the seventh day of the menstrual cycle, but they admit that making a recommendation on the basis of one subject may invite criticism. A larger study may offer more definitive data, but due to the complexity of the study design, costs may be prohibitive.
Expanding access for women
The studies will aid family planners' understanding of the two methods and help them give more specific instructions on backup methods, Dunson says. "The data we obtained really can provide the clinic managers or clinicians with information on how they can improve access to Norplant implant users, because basically we are saying that you don't need to use backup protection for an entire cycle.'' Many non-U.S. family planning programs have used backups for seven to 14 days or through an entire cycle when Norplant is initiated outside menses, he adds.
For clinicians prescribing DMPA, the new findings mean more women may choose the method, says Carlos Petta, MD, of the Centro de Pesquisas e Controle das Doenças Materno-Infantis de Cam pinas (CEMICAMP) at the Universidade Estadual de Campinas in Campinas, Brazil.
More research on the hormonal correlation to cervical mucus changes in DMPA and Norplant first-time users is scheduled for upcoming publication release, Dunson says.
References
1. Dunson TR, Blumenthal PD, Alvarez F, et al. Timing of onset of contraceptive effectiveness in Norplant implant users. Part I. Changes in cervical mucus. Fertil Steril 1998; 69:258-266.
2. Petta CA, Faundes A, Dunson TR, et al. Timing of onset of contraceptive effectiveness in Depo-Provera users: Part I. Changes in cervical mucus. Fertil Steril 1998; 69:252-257.
3. Hatcher RA, Rinehart W, Blackburn R, et al. The Essentials of Contraceptive Technology. Baltimore: Johns Hopkins School of Public Health, Population Information Program; 1997.
4. Technical Guidance/Competence Working Group and World Health Organization/Family Planning and Popula tion Unit. Family Planning Methods: New Guidance. Population Reports. Series J, No. 44. Baltimore: Johns Hopkins School of Public Health, Population Information Program; October 1996.
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