Combination contraceptives: effects on weight

 

Abstract

Background

Weight gain is often considered a side effect of combination hormonal contraceptives, and many women and clinicians believe that an association exists. Concern about weight gain can limit the use of this highly effective method of contraception by deterring the initiation of its use and causing early discontinuation among users. However, a causal relationship between combination contraceptives and weight gain has not been established.

Objectives

The aim of the review was to evaluate the potential association between combination contraceptive use and changes in weight.

Search methods

We searched the computerized databases CENTRAL (The Cochrane Library), MEDLINE, POPLINE, EMBASE, and LILACS for studies of combination contraceptives, as well as ClinicalTrials.gov and International Clinical Trials Registry Platform (ICTRP). Searches were conducted from January to May 2011. We also wrote to known investigators and manufacturers to request information about other published or unpublished trials not discovered in our search.

Selection criteria

All English-language, randomized controlled trials were eligible if they had at least three treatment cycles and compared a combination contraceptive to a placebo or to a combination contraceptive that differed in drug, dosage, regimen, or study length.

Data collection and analysis

All titles and abstracts located in the literature searches were assessed. Data were entered and analyzed with RevMan. A second author verified the data entered. For continuous data, we calculated the mean difference and 95% confidence interval (CI) for the mean change in weight between baseline and post-treatment measurements using a fixed-effect model. For categorical data, such as the proportion of women who gained or lost more than a specified amount of weight, the Peto odds ratio with 95% CI was calculated.

Main results

We found 49 trials that met our inclusion criteria. The trials included 85 weight change comparisons for 52 distinct contraceptive pairs (or placebos). The four trials with a placebo or no intervention group did not find evidence supporting a causal association between combination oral contraceptives or a combination skin patch and weight change. Most comparisons of different combination contraceptives showed no substantial difference in weight. In addition, discontinuation of combination contraceptives because of weight change did not differ between groups where this was studied.

Authors' conclusions

Available evidence was insufficient to determine the effect of combination contraceptives on weight, but no large effect was evident. Trials to evaluate the link between combination contraceptives and weight change require a placebo or non-hormonal group to control for other factors, including changes in weight over time.

 

Plain language summary

Effect of birth control pills and patches on weight

Weight gain is thought to be a side effect of birth control methods. Many women and healthcare providers believe that pills and patches cause weight gain. Concern about weight gain can limit the use of these effective birth control methods. Fear of weight gain keeps some women from starting the pill or patch. Women may stop using the pill because they think it caused weight gain. This review looked at trials of birth control pills or patches where the woman's weight was measured.

We did a computer search for studies of pills or patches containing two types of hormones. We also wrote to researchers and manufacturers to find other trials. We included randomized trials in the English language if they had at least three treatment cycles. The studies also had to compare two types of birth control methods or one type with a 'dummy' method.

We found 49 trials. These trials compared 52 different pairs of birth control methods, or a birth control method and a 'dummy' method. The four trials with a dummy or no method group did not show that these pills or patches led to weight change. Most studies of different birth control methods showed no large weight difference. Also, women did not stop using the pill or patch because of weight change. The evidence was not strong enough to be sure that these methods did not cause some weight change. However, we found no major effect on weight. To look at the link between these birth control methods and weight change, studies should have a 'dummy' method or a group not using hormones. Having that type of control group would help remove other factors, such as weight change over time.

 

摘要

背景

複方避孕藥對體重的影響

體重增加通常被認為是複方避孕藥的副作用，許多婦女和臨床人員也都相信此相關性的存在。對於服用高效力荷爾蒙避孕藥而導致體重增加的問題可能會造成女性提早中斷使用或是不願意使用此避孕藥。然而，複方避孕藥和體重增加之間的因果關係其實是未被證實的。

目標

此回顧研究的目的在評估使用複方避孕藥和體重增加之間的潛在關係。

搜尋策略

我們針對複方避孕藥搜尋了電子資料庫(MEDLINE、POPLINE、CENTRAL、EMBASE、以及LILACS)和臨床試驗數據的搜尋。我們並寫信給已知的研究員和廠商請求給予我們其他尚未發現的已出版或是未出版的試驗。

選擇標準

所有至少有三個治療週期的英文隨機控制試驗，用來比較複方避孕藥與安慰劑之間，或不同的成份與劑量的複方避孕藥之間，或使用的長短等均被納入。

資料收集與分析

所有找到的標題和摘要都進行評估。數據都輸入RevMan進行分析，跟第二位作者進行核對。根據現有的數據，平均差異使用固定效應模型，和95%信賴區間(95%CI)計算出的基線和治療後之間平均體重的變化，皮托比值和95%信賴區間(95%CI)來計算多少比例婦女體重增加或減少是否真的超過規定的重量。

主要結論

這3個安慰劑對照隨機試驗沒有找到足夠的證據支持複方口服避孕藥或避孕貼片和體重增加之間的因果關係。大多數比較不同的複方避孕藥對體重影響的實驗也沒有看到有實質上的差異。此外，在這些研究當中，也沒有看到因為體重增加而停止使用避孕藥的差異。

作者結論

現有的證據不足以來證明複方避孕藥對於體重所產生的影響，但沒有明顯的影響是肯定的。

翻譯人

本摘要由臺灣大學附設醫院林思宏翻譯。

此翻譯計畫由臺灣國家衛生研究院(National Health Research Institutes, Taiwan)統籌。

總結

體重增加被認為是避孕藥的一個副作用。許多婦女和保健人員相信避孕藥和避孕貼片都會導致重量增加。擔心體重增加會影響女性使用這類的避孕方法，甚至使婦女不想開始使用避孕藥或避孕貼片。婦女也許會停止使用避孕藥因為他們認為它導致了體重的增加。這篇回顧研究以女性的體重為估量來試驗避孕藥或貼片的影響，我們對於複方的避孕藥或貼片用電腦搜尋的方式做研究。我們也寫給研究員和廠商以尋求其他的試驗。我們納入了至少有3個治療週期的英文的隨機試驗。這些試驗是比較兩種不同的節育方法或一種結育方式與安慰劑的比較。三項與安慰劑比較的研究顯示避孕藥丸或貼片並不會導致體重增加，不同的避孕方法在體重的影響上也沒有差異。此外，婦女也沒有因為體重增加而停止使用避孕藥或避孕貼片。沒有足夠的證據顯示以這些方法避孕會造成體重的增加。所以對體重沒有重大影響。