CHAPTER 1.1 LITERATURE REVIEW AND OBJECTIVES
1.1.4 SIDE EFFECTS
1.1.4.2 Weight Gain
effect ofIPCs,with reported incidences of 1-2% (Fraser, 1983). Menstrual irregularities are reported to occur more often with DMP A than with NET -EN use (Fraser, 1982; Fraser, 1986b).
Amenorrhoea has been found to be more frequent in obese women than in underweight women (Fraser and Weisberg,1981; Benagiano and Primerio, 1983b). Lande (1995) suggests that bleeding patterns with IPC use may differ with ethnicity. For instance he reports that Southeast Asian women using DMP A reported more days of spotting and bleeding than those in the Caribbean, Europe,South East Asia,or North America,and amenorrhoea was reported more often by North African women than by European women.
Conclusion
Bleeding disturbances with IPC use are the norm. Amenorrhoea is the most prevalent menstrual irregularity, especially with DMPA, and incidence increases with duration of use (Table 1.1.3). The weight of evidence suggests that menstrual irregularities are reported to occur more often with DMP A than with NET-EN use. Some studies raise the possibility that factors such as body weight and ethnicity may influence the frequency of bleeding disturbances.
studies comparing weights in women receiving DMP A with non-hormonal contraceptives users. Whilst all studies showed higher weights amongst the DMP A users,Westhoff suggests that the findings are not conclusive as the studies did not consider the differences in weight of study participants when contraception was started, and that several
confounders - age,parity, smoking - were not taken into account by the investigators.
Westhoff (1996) also reviewed a number oflongitudinal studies and opined that,since these studies did not include a control group, the observed changes in weight could not be attributed to DMPA use. Indeed the author of one of the studies she reviewed, who found a small mean weight gain of3kg with 5-8 injections (n=76),reported that this finding had
"little statistical validity" (Fraser and Dennerstein, 1994, p.555). Westhoff (1996,p.404) concluded that "Weight gain is not inevitable during DMPA use, although some of the other data suggest that DMP A or MPA use may be associated with increased appetite".
Taneepanichskulet al (1998),in a study designed to limit some confounders through subject selection and matching techniques, found no difference in the mean weight of 50 DMP A users at 120 months of use and 50 women using an IUD over the same period. These authors,like Westhoff, suggested that the conflicting findings of studies reporting on weight changes with DMP A use results from differing study designs and the lack of control for confounding factors such as age,parity,smoking, income,nutrition,lifestyle and duration of contraceptive use.However, more recently, Espeyet al (2002) studied weight gaininNavajo DMPA users (n=172) and non-users (n=134). After controlling for age, parity and initial weight,they found that DMPA use is associated (p<0.001) with weight gain in this population and that weight gain increased with duration of use.These authors also point to possible metabolic differences between racial and ethnic groups as this study demonstrated greater weight gain with injectable use than that reported in studies of non-
49
Navajo DMPA users. Bahamondeset al (2001) also concluded that weightincreases in DMP A users were significantly higher compared with IUD users. This finding was based on a five year retrospective record review of 103 DMP A users and an equal number of IUD users.
As already highlighted above,there is concern that weight gain increases with increased duration of use of IPCs. Schwallie and Azenzo (1973) found that weight, in DMP A users, increased over time,and Westhoff (1996) reported the weight gain in this study as 10kg over five years. Bigriggetal's(1999) review ofDMPA suggests that studies have shown (unreferenced) that there is an increase in weight gain over time with DMPA,reporting that the mean weight increase after a year was 2kg,but after 5.5years of use it was 9kg.
Benagiano and Primiero (1983b,pA8) make similar inferences about weight gain and NET- EN use,saying that there is " ...a direct correlation between total dose over time and gain in body weight".
Incomparing DMPA and NET-EN, the findings on weight gain appear to be similar (Table 1.1.3),although comparative studies are few and far between. The Multi-national WHO comparative clinical trial (World Health Organization, 1978) found no statistical difference in weight gain between NET-EN and DMPA,after a year of use. The weight gain with NET-EN was reported as 1.5kg and with DMPA was 2.0kg.Chinnatamby (1971) reported that changes in weight changes are more frequent amongst DMPA than NET-EN users, but found that weight change was not given as a reason for discontinuing the method. Salemet al(1988) reported no statistically significant increase in mean weight gain between DMP A and NET-EN users.
Conclusion
Few studies on the association between weight gain and IPC use have dealt adequately with confounders including age,weight at the beginning of the study,nutritional habits, ethnicity and level of physical activity. Findings on weight gain and IPC use are inconclusive,
although findings from more recent studies seem to indicate that there may be an
association. There appears to be little evidence of differencesinweight gain between users ofDMPA and NET-EN.