Abstract
Background:
The fear of weight gain is one of the adverse events that make women to discontinue Implanon® (etonorgestrel) contraceptive. Black women are more prone to gain weight with the use of such progestogen-only contraceptives than women of other racial groups. The weight of women is also an important consideration since it influences the concentration of the active drug and may predispose to failure at a higher weight profile.
Information on weight changes with the use of etonorgestrel implant is scarce in our sub-region. We therefore explored the direction and extent of weight changes among women in different weight categories and determined the predictors of the final body weight during use of Implanon®.
Materials and Method:
This was a retrospective study of all women that accepted implanon at the Family Planning Unit of the Jos University Teaching Hospital, Jos Nigeria from March 2007 to March 2014. Data analysis was carried out using Stata version 12.1. The socio-demographic data and reproductive histories were extracted from the records and the duration of use of the implant, reasons for discontinuation and the initial weight and at follow up were analysed.
Results:
Over 99% of the women who had Implanon® were parous and the commonest contraceptive they had used previously was the injectables. However, almost a quarter (22.8%) were accepting Implanon® as their first ever contraceptive method. The mean baseline weight was 64.4 ± 12.1 kg and the median weight was 63.0 kg. The average months of use of Implanon® in this study was 27 months and there was a mean increase in body weight of 2.5 kg during the study. However, there was a broad variability in the individual change in body weight with about 38.6% losing weight or not having any net weight change. Over three-fifths (61.4%) of the women had a net weight gain while using Implanon®. Of these women, 36.0% gained 1–5 kg, 19.2% gained 6–10 kg, 4.2% gained 11–15 kg and 2.0% gained more than 16 kg with the maximum gain at 26 kg. The mean weight changes were 0.8 kg, 1.6 kg, 3.2 kg and 3.3 kg respectively for the first, second, third and fourth years of Implanon® use respectively. Implanon® was removed on account of weight gain in 3.8% of those women who had removed the implant. There was no statistically significant difference in weight gain among the different weight categories: women who had an initial weight above 90 kg gained less than 1 kg compared to those who had normal weight (for this study <70 kg) at the baseline that gained on average more than 2.0 kg. The most significant predictor of the final body weight with Implanon® use was the initial body weight which predicts it in 83.5% of the time (p-value 0.000, CI 0.99, 1.05).
Conclusion:
There was a broad variability in weight changes with the use of Implanon® and the initial body weight is the most significant predictor of the final body weight. Therefore implanon can be used by women of all weight categories including those considered to be obese.
Keywords: body weight change, Implanon (etonorgestrel) contraceptive, Jos Nigeria
INTRODUCTION
Progestogen-only contraceptive implants give a highly efficacious, reversible method of contraception with failure rates that are sometimes similar to those of sterilization1. However, weight gain is one of the adverse events patients complain of with the use of such contraceptives2. Increase in weight also constitutes a significant reason clients adduce for the discontinuation of these contraceptives3. One study among a multi-racial cohort has shown that black women are particularly more prone to gain weight with the use of these progestogen-only contraceptives than women of other racial groups4.
The weight of the patients is also an important consideration in acceptors of implants because the higher the weight of the women the higher the risk of failure. Women who weighed more than 70 kg at baseline were more likely to have had a method failure with Norplant than lighter women1, 5. Indeed, obese women were purposively excluded in the initial trial of implanon for this reason1. The higher failure rate at higher body weight is most probably the direct result of the influence of weight on the serum concentration of the active drug etonorgestrel in the body. In a study comparing the serum concentrations of implanon among different weight categories, lower body weight was found to be associated with a higher serum concentration of implanon. The converse was also true6. About 12% to 21% of implanon users were found to have had clinically significant weight gain.7, 8 Pooled data from many studies have also shown that over a two-year period, Implanon® users had an average increase of 2.6% of their initial body weight. However, this average weight increase was similar to other controls using non-hormonal methods9, 10. This suggests that women tend to gain weight as they aged regardless of the use of any contraceptives as a result of multi-factorial reasons; genetics, environmental factors, lifestyle and repeated pregnancies with the attendant difficulty to return to their pre-pregnancy weight11, 12.
Studies in our sub-region exploring the effect of implants on weight gain are scarce. The effect of etonogestrel implant on weight gain especially has not been extensively studied11. We hypothesized that the use of Implanon® among women in our sub-region will lead to significant weight changes over time. We therefore aim to explore the direction and extent of the changes in body weight among women of different weight categories.
MATERIALS AND METHODS
Design and period of the study
This was a retrospective, observational study that was carried out at the Family Planning Unit of the Department of Obstetrics and Gynaecology of the Jos University Teaching Hospital, Jos North Central Nigeria. The study spanned a 7-year period from March, 2014 to March 2014.
Recruitment and Follow up
All the women who had Implanon® inserted for contraception during the study period and came for at least a follow up visit were included in the study. A chart review was carried out. Data on the demography and reproductive histories were obtained. The dates of the insertion and removal of Implanon® were noted. The duration of use of the implant and the reason for discontinuation were also documented.
After Implanon® insertion, the women were followed up with yearly scheduled visits to the clinic. The women were however advised to come to the clinic anytime they had any problems or adverse effect with the Implanon® regardless of their scheduled visits.
The body weight was measured at each visit using the same scale and measurement protocol. A weight of 70 kg and below was considered as normal in this study.
Statistical analysis
Descriptive and analytic statistics were carried out on all data where appropriate using Stata version 12 (StataCorp, College Station, Texas, USA). The descriptive statistics were percentage, mean, median, standard deviation, range, interquartile range, p-value and 95% confidence interval. For weight changes between baseline and the final follow up visit, the paired t test was carried out. Significance was established at the level of 0.05 for all analyses. Linear regression analysis was employed to examine predictive characteristics in relation to weight changes.
RESULTS
During the study period, 1482 women accepted Implanon® but only 902 (60.9%) had at least one follow up visit a month apart and were included in the study. Their body weights were taken at baseline and at each follow up visit. For those who had more than one follow up visit, only the weight at the last follow visit was compared with the baseline weight. Among the 902 women who came for follow up visits, 850 (94.2%) had complete documentation of both initial and final body weights in their records. Table 1 show the demographics of the women. The median age of the women was 30 years; interquartile range 27–35 years and median parity of 3 (IQR 2–4).
Table 1:
Socio-demographics of Implanon® acceptors
| CHARACTERISTICS | Implanon (N=902) | |
|---|---|---|
| Age( in years) | Number | Percentage |
| ≤19 | 7 | 0.8 |
| 20–29 | 354 | 39.2 |
| 30–39 | 470 | 52.1 |
| 40–49 | 70 | 7.8 |
| 50–59 | 1 | 0.1 |
| Religion | ||
| Christian | 788 | 87.9 |
| Islam | 108 | 12.1 |
| Educational Status | ||
| No Formal education | 17 | 2.0 |
| Some Primary Education | 14 | 1.7 |
| Completed Primary Education | 99 | 11.8 |
| Some Secondary Education | 84 | 10.0 |
| Completed Secondary Education | 210 | 25.1 |
| Tertiary Education | 414 | 49.4 |
Over 99% of the women had at least one delivery by the time of accepting Implanon®. Implanon® was the first contraceptive method to be used by 22.8% of the women with the injectable contraceptives as the commonest method used previously. The reproductive history of the women is depicted in table 2.
Table 2:
Reproductive history of Implanon® acceptors
| Variable | Number | Percentage |
|---|---|---|
| Parity | ||
| 0 | 7 | 0.8 |
| 1 | 130 | 14.4 |
| 2 | 212 | 23.5 |
| 3 | 205 | 22.7 |
| 4 | 155 | 17.2 |
| 5 | 88 | 9.8 |
| ≥6 | 107 | 11.6 |
| Children born alive | ||
| 0 | 7 | 0.8 |
| 1 | 130 | 14.4 |
| 2 | 209 | 23.2 |
| 3 | 206 | 22.8 |
| 4 | 164 | 18.2 |
| 5 | 82 | 9.1 |
| ≥6 | 101 | 11.5 |
| Route of last Delivery | ||
| Vaginal | 738 | 86.1% |
| Caesarean | 89 | 10.4% |
| Complicated | 30 | 3.5% |
| Previous contraceptive USE | ||
| Oral Pills | 220 | 9.4% |
| Injectables | 327 | 36.3% |
| Implanon | 10 | 1.1% |
| Jadelle | 1 | 0.1% |
| Norplant | 68 | 7.5% |
| IUDs | 85 | 9.4% |
| Others | 28 | 3.0% |
| No Contraceptive | 205 | 22.8% |
| Breastfeeding | ||
| Yes | 506 | 59% |
| No | 351 | 41% |
| Menstruation | ||
| Regular | 742 | 87.1% |
| Irregular | 110 | 12.9% |
Table 3 shows the different weight categories of the women at baseline compared to their final visit. At baseline 71.8% of the women had a body weight of 70 kg and below. However, by the last visit or at removal only 63.7% of the women were within the ‘normal’ body weight for the study with over a third of the women weighing more than 70 kg. The commonest weight category at baseline was 51–60 kg which changed to the 61–70 kg group during the follow up period. This indicated an increase in the general body weight of the women with a mean increase of 2.5 kg. These women used Implanon® for an average of 27 (±14.7) months.
Table 3:
The different weight categories at baseline and at the final visit
| BASELINE WEIGHT (W0) | FINAL WEIGHT FOUND (W1) | |||
|---|---|---|---|---|
| WEIGHT GRP (kg) | No | % | No | % |
| 31–40 | 7 | 0.8 | 3 | 0.4 |
| 41–50 | 96 | 10.7 | 82 | 9.6 |
| 51–60 | 274 | 30.6 | 215 | 25.1 |
| 61–70 | 266 | 29.7 | 245 | 28.6 |
| 71–80 | 164 | 18.3 | 180 | 21.0 |
| 81–90 | 66 | 7.4 | 94 | 11.0 |
| 91–100 | 14 | 1.6 | 25 | 2.9 |
| 101–110 | 8 | 0.9 | 9 | 1.1 |
| 111–120 | 1 | 0.1 | 2 | 0.2 |
| 121–130 | 0 | 0 | 1 | 0.1 |
The change in weight of 2.5kg between baseline (W0) and final weight (W1) was statistically significant (paired t-test, p-value 0.001).
Among the 850 women who had both initial (W0) and final (W1) weights documented, 85 (10.0%) had no net weight gain. About a third of the women (28.6%) had a net weight loss ranging from a loss of 1 kg to 30 kg. Over three-fifths (61.4%) of the women had a net weight gain while using Implanon®. Of these women, 36.0% gain 1–5 kg, 19.2% gained 6 −10 kg, 4.2% gained 11–15 kg and 2.0% gained more than 16 kg with the maximum gain at 26 kg. The mean weight gain at one year was 0.8 kg and this doubled by the end of the second year (1.6 kg). The mean increase levelled off by the end of the third and fourth years at 3.2 kg and 3.3 kg respectively. Weight gain was the reason 25 (3.8%) women had their implant removed. These 25 women had a mean baseline weight of 75.0 kg with an inter-quartile range of 68–82 kg. Their mean follow up body weight became 83.8 kg (with inter-quartile range of 74.0– 90.5 kg) after using implanon for an average of 19 months. The mean weight increase for this cohort was therefore 8.8 kg. Two women complained of losing weight but this did not lead to the removal of the implant.
DISCUSSION
We examined the baseline socio-demographic and reproductive histories of women who accepted Implanon® during the study period and explored the characteristics that are predictive of body weight changes. The fear of weight gain is one of the reasons that influence the acceptance of contraceptive methods generally and the implants in particular2,3. The mean weight change was an increase of 2.5 kg over the average baseline weight of the women which was significant at a p-value of 0.00001. However, there was a marked variability in weight changes among the women with a range of −30 kg to +26 kg. This range was only slightly higher than the variability in weight changes (−16.3 to 32.7 kg) seen among a multiracial cohort in the US4. Variability in weight changes was documented even among users of non-hormonal methods of contraception which suggests that weight change over time is influenced by a complex interplay of multiple factors4.
In a review of pooled data from 11 international studies, all conducted outside Africa, involving 24,679 cycles2, 31% of the women experienced no net weight change or some weight loss between the baseline and the last measurement. This compares well with our study with 38.6%. Also, 49% had an increase of 0.1–5.0 kg body weight in the international series2 which is more than the 36% of 1–5 kg in our study. This perhaps is because more women in the international series had smaller weight gain of 1 – 5 kg compare to our women who are more represented in those who had a net weight gain more than 5.0 kg. This may also support the finding in some studies that black women are more prone to weight gain with Implanon®74. Furthermore, 2.3% of the women in the 11 international studies discontinued their Implanon® because of increased weight gain compared to 3.8% in our study.
We found no statistically significant difference in weight gain among the different weight categories. A study of Norplant® users found that generally there was no difference in body weight change in different categories of baseline weight13. Between the categories of initial baseline weight of 51–60 kg and 81–90 kg, the mean body weight change hovered around +2.5 kg. Except for the only woman in the 111–120 kg category who weighed 112 kg at baseline and 135 kg at the last measurement, there was a drop in the mean increase in body weight among women in all the categories above 90 kg to less than 1 kg. This may have been because the women in the higher weight categories were more self conscious of their body image and took measures to adjust for nutrition and physical activity to mitigate any weight increase14.
In our study population, the baseline weight among Implanon® users was the most significant predictor of the final body weight. Put another way, the final body weight during Implanon® use can be explained in 83.5% by the initial body weight at baseline as depicted in Figure 1.
Figure 1: Scatter plot showing relationship between changes in the final weight and the initial weight at baseline.
Figure 1 illustrates the relationship between the final weight (W1) and the initial weight (W0) at baseline.
R2=0.84
The strength of our study was the objective determination of the weight of the women at two time points using the same scale and measurement protocol. However, one weakness was our failure to measure the height of the women which resulted in our inability to calculate the individual body mass index (BMI) of each woman. Also, since the follow up weight determination depended on the women coming to the clinic, this may have introduced some bias positively or negatively as a result of loss to follow up. Nonetheless, there was no statistically significant difference in the mean baseline weight of those who came for follow up and those who did not. Our result has a high external validity since it was obtained within a normal clinic setting and not a clinical trial with stringent inclusion criteria like recruiting only those within 80% to 130% of their ideal body weight2. This may not however be generalizable to other Nigerian women seeking Implanon® as our study population was limited only to a single centre.
Despite these limitations, our study has deepened our understanding of the relationship between many baseline characteristics, Implanon® use and weight changes among our women. There was a broad variability in weight changes with the use of Implanon® and the baseline body weight was found to be the most significant predictor of the final body weight. More importantly is the fact that women in the heavier weight categories (>70 kg) are no more prone to gain weight than those who are lighter at baseline.
Table 4.
shows the different weight categories and their mean body weight at baseline (W0). The final mean body weight (W1) of the same women in each category is also depicted and the mean change for each initial weight category calculated (W1-W0).
| Weight Group (kg) | mean W0 (kg) | mean W1(kg) | Mean change in kg (W1-W0) |
|---|---|---|---|
| 31–40 | 39.0 | 41.0 | 2.0 |
| 41–50 | 47.4 | 49.3 | 1.9 |
| 51–60 | 55.9 | 58.4 | 2.5 |
| 61–70 | 65.7 | 68.4 | 2.7 |
| 71–80 | 75.1 | 77.6 | 2.5 |
| 81–90 | 84.2 | 86.6 | 2.4 |
| 91–100 | 93.8 | 94.3 | 0.5 |
| 101–110 | 104.4 | 105.1 | 0.7 |
| 111–120 | 112 | 135 | 23 |
W0 = Baseline body weight
W1 = Final body weight at follow up
ACKNOWLEDGEMENT
We most sincerely thank the Nurses/midwives at the Family Planning Unit for carrying out most of the activities pertaining to the screening, counselling, insertion, removal and follow up of the women that accepted the Implanon® contraceptive device. They are Mrs Florence E. Guful, Mrs Rose C. Bicham, Mrs Cordelia Dyangwar and Mrs Mary C. Shikgak’ah. Data analysis and writing of this paper was supported by the Medical Education Partnership (MEPIN) project funded by Fogarty International Center, the Office of AIDS Research, and the National Human Genome Research Institute of Health, the Health Resources and Services Administration (HRSA) and the Office of the US Global AIDS Coordinator under Award Number R24TW008878. The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding organisations.
REFERENCES
- 1.Glasier A Implantable contraceptives for women: effectiveness, discontinuation rates, return of fertility, and outcome of pregnancies. Contraception, 2002; 65: 29–37. [DOI] [PubMed] [Google Scholar]
- 2.Blumenthal PD, Gemzell-Danielsson K, Marintcheva-Petrovax M. Tolerability and clinical safety of Implanon. European Journal of Contraception and Reproductive Health Care, 2008; 13(S1): 29–36. [DOI] [PubMed] [Google Scholar]
- 3.Curtis KM, Ravi A, Gaffield ML. Progestogen-only contraceptive use in obese women. Contraception, 2009; 80: 346–354. [DOI] [PubMed] [Google Scholar]
- 4.Vickery Z, Madden T, Zhao Q, Secura GM, Allsworth JE, Peipert JF. Weight change at 12 months in users of three progestin-only contraceptive methods. Contraception,2013; 88: 503–508. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Chrisman CE, Curtis KM, Mohllajee AP, Gaffield ME, Peterson HB. Effective use of hormonal contraceptives Part II: combined hormonal injectables, progestogen-only injectables and contraceptive implants. Contraception, 2006; 73: 125– 133. [DOI] [PubMed] [Google Scholar]
- 6.Huber J Pharmacokinetics of Implanon An Integrated Analysis. Contraception, 1998; 58: 85S–90S. [DOI] [PubMed] [Google Scholar]
- 7.Edwards JE, Moore A: Implanon: A review of clinical studies. Br J Fam Plann, 1999; 24:3. [PubMed] [Google Scholar]
- 8.Guazzelli CAF, De Queiroz FT, Barbieri M, Torloni MR, De Araujo FF. Etonogestrel implant in adolescents: evaluation of clinical aspects. Contraception, 2011; 83: 336–339. [DOI] [PubMed] [Google Scholar]
- 9.Urbancsek J: An integrated analysis of non-menstrual events with Implanon. Contraception 1998; 58(6 Suppl):109S. [DOI] [PubMed] [Google Scholar]
- 10.Isley M Implanon: The Subdermal Contraceptive Implant. J Pediatr Adolesc Gynecol, 2010; 23: 364 – 367. [DOI] [PubMed] [Google Scholar]
- 11.Society of Family Planning. Contraceptive considerations in obese women. Contraception, 2009; 80: 583–590. [DOI] [PubMed] [Google Scholar]
- 12.Linne Y, Dye L, Barkeling B, Rossner S. Weight development over time in parous women—the SPAWN study—15 years follow-up. Int J Obesity 2003; 27: 1516–22. [DOI] [PubMed] [Google Scholar]
- 13.Kozlowski KJ, Rickert VI, Hendon A, Davis P. Adolescents and Norplant: preliminary findings of side effects. J Adolesc Health 1995; 16:373–8. [DOI] [PubMed] [Google Scholar]
- 14.Curtis KM, Ravi A, Gaffield ML. Progestogen-only contraceptive use in obese women. Contraception, 2009; 80: 346–354 [DOI] [PubMed] [Google Scholar]