Compliance
As mentioned above, a major stumbling block to the
effective use of most modern contraceptive methods is the problem of "user"
versus "method" failure. For example, most pregnancies in women taking oral
contraceptives are due to their forgetting to take the pill on one or more days. A key
advantage of Norplant implants is that one act of contraceptive acceptance by a woman will
provide up to 5 years of continuous pregnancy protection without the need to remember to
take a pill every day or check that a device is still in place (Angle, Huff and Lea 1991).
Because Norplant implants do not protect women from hepatitis B, AIDS and other sexually
transmitted diseases, women may wish to use a barrier contraceptive method in addition to
the implants to protect themselves.
Continuation
Continuation rates reported in several well-monitored
multicenter studies have ranged from 76-95% in the first year, decreasing to 25-78% by
year 5 (Table 3). The average duration of use in these studies was 3.5 years (Sivin
1988).
Table 3. Cumulative Continuation Rates per 100
Woman-Years
| |
Total
Number of Women |
Years
of Use |
1 |
2 |
3 |
4 |
5 |
| ICCR STUDIES
|
| Chile |
491 |
90% |
82% |
72% |
63% |
55% |
| Dominican Republic |
1009 |
79 |
60 |
44 |
33 |
25 |
| Scandinavia |
377 |
76 |
60 |
53 |
37 |
33 |
| USA |
396 |
82 |
65 |
50 |
44 |
N/A |
| NON-ICCR STUDIES
|
| Columbia |
389 |
92 |
76 |
68 |
N/A |
N/A |
| Egypt |
250 |
90 |
69 |
63 |
59 |
58 |
| Indonesia |
437 |
95 |
92 |
88 |
82 |
78 |
Source: Sivin 1988.
Changes in the menstrual bleeding patterns of Norplant
implants users were the main reason for stopping the method. Based on pooled data from the
International Committee for Contraception Research (ICCR) studies, approximately 9% of
women stopped using implants during the first year due to menstrual changes, but this
decreased to 3% in the fifth year.
As shown in Table 4, first-year continuation rates
for Norplant implants compare favorably with those found for other contraceptives
(Trussell et al 1990).
Table 4. First-Year Continuation Rates of Selected
Contraceptive Methods
| Method |
Continuation
Rate at One Year (%) |
| Norplant implants |
90 |
| Oral
contraceptive pills |
73 |
| IUD |
73 |
| Condom |
64 |
| Cervical cap |
63 |
| Vaginal sponge
Nulliparous
Parous |
60
53 |
| Diaphragm |
57 |
| Spermicide |
43 |
Source: Trussell et al 1990.
Outcome of Pregnancy
The use of Norplant implants does not appear to increase
the frequency of ectopic pregnancy. In pooled studies of implants users, the
incidence of ectopic pregnancies was only 1.3 per 1000 woman-years. This rate is
comparable to the ectopic pregnancy rate of 1.4 per 1000 woman-years reported in the 1980s
for US women aged 15 to 44 who were noncontraceptive users (Sivin 1990).
If a woman does become pregnant with Norplant
implants in place, however, she is more likely to have an ectopic pregnancy (20-30%).
Furthermore, because the risk of ectopic pregnancy increases slightly with duration of
Norplant implants use, it should be ruled out in any woman suspected of being pregnant
(Croxatto 1993). Therefore, all women with Norplant implants who present with symptoms of
pregnancy should be carefully evaluated.
Norplant implants use has not been associated with other
pregnancy-related problems. To date, there has been only one known instance of a birth
defect among women using implants. This case involved delivery of a male infant who
was born with ambiguous genitalia (underdeveloped penis, rudimentary scrotum and one
testis absent). It is highly unlikely that these defects were due to use of implants
(Croxatto 1993).
One of the most important characteristics of Norplant
implants is that their contraceptive effect istotally reversible. Once the implants are
removed, serum levels of LNG become undetectable within a few days. This results in a
prompt return to the woman's previous level of fertility. Several studies have reported no
long-term effects on future fertility, regardless of age or parity (i.e., young women with
no previous pregnancies can safely use this method). In fact, pregnancy rates for women
who have used Norplant implants compare favorably with those not using any contraception
previously (Sivin 1988). For example, as shown in Figure 9, over 20% of women
wanting to become pregnant did so within 1 month after removal, more than 50% within 3
months, 86% within 12 months and 93% within 24 months.
Figure 9. Pregnancy After Removal of Norplant Implants
Source: Sivin 1988.
Extensive clinical use in over 4 million women in 30
countries, including more than 1 million in the USA, has shown that Norplant implants are
well tolerated by most women. A major advantage of implants is that they do not
contain any estrogen, which causes many of the side effects associated with the use of
COCs. The most common side effect in Norplant implants users is a change in the
menstrual bleeding pattern (Darney et al 1990b). Unlike COCs, which provide a
predictable and adequate amount of estrogen, estrogen levels in implants users vary from
day to day. As a consequence, the excellent cycle control (i.e., lack of breakthrough
bleeding and spotting) typical for COC users does not occur with Norplant implants users.
Instead, breakthrough bleeding and spotting are common, especially during the first 6 to 9
months of use.
This problem, as well as the other minor side effects seen
with Norplant implants, is similar to those known to occur with progestin-only pills and
injectables.
Although nearly all users will experience one or more side
effects during the 5 years of use, seriousproblems are very rare (Darney et al 1990b).
Unfortunately, despite the fact that most side effects are minor, they may prompt users to
stop using implants. Therefore, careful explanation of the side effects before
Norplant implants are inserted as well as reassurance that rarely do they represent
a risk to the client's health helps in decreasing any concerns. As is the case with other
contraceptive methods, thorough counseling of potential users before insertion has
a major impact on user satisfaction and continuation rates.
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