Contraceptives & the Menstrual Cycle
The Effects of Depo-Medroxyprogesterone,
Acetate (Depo-Provera), and
Norplant
on the Menstrual Cycle
by
L. Cvetkovich MD, FACOG
Depo-Provera and Norplant are both long acting hormonal contraceptives. They therefore have many similarities and a few important differences.
"Similarities"
Both drugs are progestational agents, or PROGESTINS. This is an important fact because even though they are quite different, Depo-Provera being a true progesterone with 21 carbons, and Norplant (chemical name levonorgestrel) being an androgen (male hormone) with 19 carbons, they both have progesterone-like effects on the reproductive organs and metabolism. They both have as their potential mechanisms of action the same three effects that oral contraceptives have which are well known to most NFP providers:
- The inhibition of ovulation by inhibition of the LH surge;
- The thickening of the cervical mucus and prevention of sperm migration, and
- The alteration of the endometrium to either an atrophic or dissynchronous state such that implantation is prevented.
"Differences"
The long acting medroxy-progesterone acetate which comprises Depo-Provera (hereafter DMPA), is given by injection in the muscle where it is released slowly over the next 3 months after which time the injection is repeated. Norplant on the other hand consists of 36 mg. Of levonorgestrel encased in 6 silastic rods which are implanted via a 1/2 inch incision in the upper forearm...the drug being slowly released over 5 years.
Depo-Provera is a very strong suppressor of ovulation and probably works via the first mechanism (i.e., the inhibition of the LH surge) most of the time, but not 100%. Norplant on the other hand, suppresses ovulation to a much lesser degree and works primarily via the second two mechanisms (i.e., the thickening of the cervical mucus and prevention of sperm migration). In fact, after the first year, as many as 50-60 % of clients on Norplant will have fairly regular menstrual cycles, whereas after three injections or nine months of DMPA, about half of clients will be totally amenorrheic.
Both drugs differ from oral contraceptives in that they contain no estrogen and therefore are often recommended to those women with contraindications to estrogen use such as estrogen induced hypertension, deep vein thrombophlebitis, estrogen dependent cancer etc.
Effects & Management
Side effects for both methods include:
- weight gain
- headaches
- decreased libido
- hair loss
- acne
- irregular Bleeding*
*Irregular bleeding is the most frequent and troublesome side effect. This bleeding is not usually heavy but the fact that it is unpredictable is a significant drawback. Studies following Norplant users found that days of bleeding amounted to 100 days out of the first year. For this reason a full 70% of clients discontinue the Norplant prior to the full 5 years.
The primary effect of the progestins on the NFP charting will be evidence of anovulation or oligoovulation, and decreased cervical mucus.
Since the average time to a pregnancy after the last injection of DMPA is a 8-9 months, and 70% of women on DMPA for two years were amenorrheic after discontinuation, one must be particularly patient with regard to the return of regular cycles and communicate this attitude of patience to the client couple.
A decreased amount of cervical mucus due to the effects of DMPA on the cervical crypts, may also be a problem. It is unknown at this point whether the cervical crypts ever return to their previous state and if so in what time frame.
DMPA's effect on the BBT is a sustained elevation of the waking temperatures as long as the hormone was active in the body with a slow return to the normal cyclic, biphasic pattern over several months. However, to my knowledge there has been no documentation of this course of events.
Norplant users on the other hand, would be expected to show a more rapid return to fertility and regular cycles because many women are ovulatory (40-80 % of cycles) on Norplant (even though those ovulatory events are very abnormal). The rapid return to fertility is seen also in that 80% of users were pregnant within a year of discontinuation.
"Management"
With regard to management of these clients, they would require the same management protocols and instructions the NFP practitioner would use for those clients coming off oral contraceptives, or breastfeeding/wearing or indeed any temporary anovulatory state with the difference that the return to regular cycles would be more prolonged if DMPA were involved.
The important guiding principle should be to use the most conservative guidelines until regular cycles are established and support the client couple in being patient during the time it takes for normal ovarian function to return...particularly if the guidelines dictate prolonged abstinence.
Copyright @ 1999, Diocesan Development Program fro Natural Family Planning, United States Conference of Catholic Bishops. The text and illustrations may be reproduced in whole without alteration or change by Catholic dioceses, parishes, schools, organizations, and newspapers, provide such reprints include the following notice:
Reprinted from FOCUS NFP Series, Copyright @ 1999, Diocesan Development Program for Natural Family Planning, United States Conference of Catholic Bishops, Washington, D.C. All rights reserved.