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Recommendations for Contraceptive Use |
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NORPLANT® Implants |
Q.1. When can NORPLANT®
Implants be inserted (interval)? How soon after the insertion are NORPLANT®
Implants effective? Is there a need for a back-up method?
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| a) NORPLANT®
Implants may be inserted any time you can be reasonably sure the
woman is not pregnant, for example, during the 7 days which begin with the onset of
menses (days 1 through 7 of the menstrual cycle). |
a) Blood levels of
levonorgestrel rise to a level sufficient to prevent conception within 24 hours of
insertion.
- NORPLANT®
Levonorgestrel Implants: A Summary of Scientific Data. Monograph. New York, The
Population Council, 1990, p 2.
Although ovulation can occur as early as day 10 of the
menstrual cycle, this is rare4. Fertile ovulation is very uncommon before day
121. Intercourse 5 days before ovulation may have as much as a 5% chance of
resulting in pregnancy2; however, since experts believe there are few fertile
ovulations before day 13, there is only a very small chance that intercourse on day 7 of
the cycle could result in pregnancy1.
In general, use of NORPLANT® Implants within
the first 7 days after the woman's normal menses would assure that the probability of the
woman already being pregnant, or becoming pregnant, is extremely low3.
- The Technical Guidance Working Group
has reached this conclusion after a thorough review of the available literature and
consultation with the following experts:
William Collins, PhD, DSc, Department of
Obstetrics and Gynecology, Kings College, UK
Jeffrey Spieler, MSc, Research Division, Office
of Population, USAID.
- Dixon GW, Schlesselman JJ, Ory HW,
Blye RP. Ethinyl estradiol and conjugated estrogens as postcoital contraceptives. Journal
of the American Medical Association 1980;244:1336-1339.
- Gray RH, Pardthaisong T, McDaniel EB,
Doyle P. The timing of the first insertion of Depo Provera. IPPF Medical Bulletin
1975;9(3):3-4.
- Schiphorst LE, Collins WP, Roystar JP.
An estrogen test to determine The times of potential fertility in women. Fertility and
Sterility 1985;44:328-334.
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| b) For women having menstrual
cycles, no back-up method is needed if she is in the first 7 days of her menstrual cycle
and is still menstruating. If she is in the first 7 days of her cycle, but is not
menstruating, some programs may recommend use of a back-up method for 1 week. NORPLANT®
Implants may be inserted anytime you can be reasonable sure the
woman is not pregnant. However, if insertion is done after day 7 of a regular cycle, a
back-up method (or abstinence) may be needed (see c., below). |
b) It is probable that NORPLANT®
Implants effectively thicken cervical mucus within 24 hours. Consistent with this theory,
progestin-only pills have been shown to produce a thickened mucus with low sperm
penetration within 3 to 4 hours after pill ingestion. Natural progesterones also cause
cervical mucus to become scant, thick and sticky decreasing or inhibiting sperm
penetration, within 24 hours, but sometimes within 48 hours. Clinical judgement isalso
consistent with this theory.
- The Technical Guidance Working Group
(GWG) has reached this conclusion after a thorough review of the literature and
consultation with the following experts: Gary Grubb, MD, MPH, The RW Johnson
Pharmaceutical Research Institute, Raritan, NJ, USA
Michael Orme, Professor of Clinical
Pharmacology, The University of Liverpool, UK.
- Wright SW, Fotherby K, Fairweather F.
Effect of daily small doses of Norgestrel on ovarian function. Journal of Obstetrics
and Gynecology of the British Commonwealth 1970;77:65-68.
- Tsibris JCM. Cervical mucus, in Gould
JJ, Josimovich JB (eds). Gynecologic Endocrinology. New York, Plenum Medical Book
Company, 1987, pp 175-183.
- Insler V, Melmed H, Eichenbrenner I,
Serr D, Lunenfeld B. The cervical score: A simple semiquantitative method for monitoring
of the menstrual cycle. International Journal of Gynaecology and Obstetrics 1972;10(6):
223-228.
- Flynn AM, Lynch SS. Cervical mucus and
identification of the fertile phase of the menstrual cycle. British Journal of
Obstetrics and Gynaecology 1976(83):656-659.
- Moghissi KS, Syner FN, Evans TN. A
composite picture of the menstrual cycle. American Journal or Obstetrics and Gynecology
1972;114(3):405-418.
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| c) Although
there is good reason to believe the effect on cervical mucus will promptly provide
contraceptive protection within 24 hours, it may be prudent to consider a back-up method
for up to 7 days. (See Q.2. for postpartum insertion and Q.3. for post-abortion
insertion.) |
c) Some programs might recommend
a back-up method for women who are not menstruating at the time of NORPLANT®
Implants initiation because there is a very slight risk of conception from unprotected
intercourse on day 7 of the cycle. |
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