BODY WEIGHT CHANGES IN WOMEN USING IMPLANON IN JOS, NIGERIA.

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.