Combined Oral Contraceptives
Perceptions of weight gain as a result of using combined oral contraceptives is widespread in many countries among both women and providers.[6–8,11] Discontinuation due to concerns about weight gain is also reported widely, and in the USA it is the most common reason given for discontinuation of COCs. In one study of providers, 81.2% of nurses and doctors perceived weight gain to be a side effect of COCs. However, the research evidence has found no convincing evidence to support an effect on weight.[14,33–37] A systematic review published in 2004 updated as a Cochrane review in 2008 assessed the evidence and concluded that the existing data support the notion that women using COCs gain no more weight than nonhormonal user controls or other contraceptive method users. The review assessed 47 randomized controlled trials, three of which were placebo controlled. However, owing to the limited number of placebo-controlled trials, it is stated that there is not enough evidence to show that these methods do not cause some weight gain. Two randomized placebo-controlled trials did not find any evidence of weight gain,[35,36] and in one of these trials a range of COC formulations were included alongside the placebo and 30% of women across all groups gained approximately 2 kg. A comprehensive review published in 2000 included double-blinded studies, comparative and noncomparative studies, and concluded that there was no evidence for weight gain. In this review, the noncomparative studies evaluated reported a slight increase in weight of approximately 0.5 kg but less than 2 kg over an approximately 1–2-year time period. However, as no comparison groups are included, it cannot be concluded that the COC regimen caused the increase.
Evidence-based Guidelines for COCs
Hatcher writes in the widely read Contraceptive Technology handbook that there is no association between weight gain and oral contraceptive use, and includes weight gain in his table along with the description stating "Common myths that make women hesitate to use COCs". The Family Planning Global Handbook for Providers is an evidence-based guidance developed through a worldwide collaboration of experts and supported by the United States Agency for International Development, the WHO and Johns Hopkins University. This handbook is seen as the gold standard for current guidance on all contraceptive methods and is seen as an essential desk aid to family planning providers globally. This handbook is widely available, and in the latest edition (2007) reassures in its "Commonly Asked Questions" section that most women do not change weight as a result of COC use ( Box 1 ).
The research may be reassuring, but despite the strong evidence against weight gain that has been available for many years, perceptions regarding this side effect continue. Often weight gain is seen as worse than the other 'real' side effects of COCs. In the USA weight gain is considered to be one of the most common problems with COC use, more common in fact than nausea, headache and menstrual abnormalities. Looking back, concerns over weight have been appearing in the literature for many decades. Over 40 years ago data collected on COC use in the 1965 fertility survey found that the main reason for discontinuation of oral contraceptives was owing to side effects, with the main complaints reported being weight gain along with fluid retention. To understand more about the perceptions of weight gain, it may be important to consider the history of COCs. Since their introduction in the early 1960s there has been a gradual reduction in the dosage of steroids to address a range of health issues. Unlike some progestogen-only methods of contraception such as DMPA-intramuscular (IM) and norethisterone enanthate (NET-EN), which have not changed in formulation, the changes in dose of ethinyl estradiol (EE) in COCs over time have made it more difficult to compare results from earlier published studies where the EE content of COCs may have been much higher. Cohort studies published since the late 1990s have been more likely to specify the formulations, while many cross-sectional studies have collected data from women who may not have known the formulation of the COCs they had used. As high estrogen doses have been linked to weight gain and fluid retention, older brands of high-dose COCs may have been responsible for higher reporting of these side effects compared with more recent lower dose COCs. This may have resulted in the continuing association of COCs and weight gain, despite the new evidence suggesting otherwise.
Similar to studies reporting individualized responses to DMPA, studies on COC users also show a range of weight changes in response to COC use, with women losing weight as well as gaining while some experience no change.[23,42] One study reported that 39% of COC users lost weight while 33% gained up to 2 kg. Many studies show that a percentage of women lose weight but this is rarely reported, indicating a need for more balanced reporting.
Mechanism of Weight Change in Combined Contraceptive Users There are several possible mechanisms in which weight gain could occur as a result of COC use. Increased appetite could result from a suppression of serum cholecystokinin. One study reported that half of adolescents and providers believed that COC use increased appetite and 60% of the adolescents in this study also believed that COCs caused weight gain. It is suggested that estrogen in COCs causes fluid-retention weight gain by direct stimulation of the renin–angiotensin system, which can lead to water retention, which in turn leads to sodium retention. Several older studies comparing different dosages of estrogen suggested that lower dose COCs reduce fluid retention.[44,45] One study that compared low-dose estrogen COCs users with non-user controls found that there was no difference between users and controls in weight gain, and where there was small weight gain in both groups this was due to fat deposition and not fluid retention. COCs containing the progestin drospirenone may assist in helping women who are susceptible to weight gain minimize fluid retention, in particular related to premenstrual syndrome. This progestin has antimineralocorticoid and antiandrogenic properties.[46,47]
Expert Rev of Obstet Gynecol. 2011;6(1):45-56. © 2011
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Cite this: Weight Change and Hormonal Contraception: Fact and Fiction - Medscape - Jan 01, 2011.