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Contraceptive Update: Contraceptive Pearls
(June 2003)
The "Contraceptive Pearls" offer answers to commonly asked questions about family planning. These "Pearls" were prepared by Dr. James D. Shelton, Senior Medical Scientist, Office of Population and Reproductive Health, United States Agency for International Development (USAID). They are reprinted with permission. To view archives of Jim Shelton's Pearls online, visit Jim Shelton's Pearls online
Oral Contraceptives and Weight Gain
Question: In our clinic, clients sometimes complain about weight gain while taking oral contraceptives (OCs). Do OCs cause weight gain?
Answer: Probably not on average. If they do, it is very subtle. A recent Cochrane Review assessed 42 trials including 3 pertinent placebo-controlled randomized clinical trials (one of which was actually with the contraceptive patch). Notably, none of the randomized trials showed a statistically significant difference in weight gain for OC users compared to the placebo group. The report concludes: "Available evidence is insufficient to determine the effect of combination [oral] contraceptives on weight, but no large effect is evident."
Reference: Gallo MF, Grimes DA, Schulz KF et al. Combination contraceptives: effects on weight (Cochrane Review). In: The Cochrane Library, Issue 2. Oxford, UK: Update Software, 2003.
More on Oral Contraceptives and Weight Gain
Question: The information you gave in your last Pearl (that OCs have little or no effect on weight) caused quite a commotion among our clinic staff. Many of us have ourselves experienced weight gain on the pill or know someone else who has. Moreover, we have made a point of telling our OC clients that they might gain weight. How can there such a disparity between the studies and what seems so obvious?
Answer: Good question. Here are some possibilities as I see it:
1) The average doesn't represent everybody equally. It is conceivable that some women gain weight on the pill, others lose weight and others stay about the same. Those who gain weight may be more vocal.2) Cyclic changes in weight. For example some women may "retain fluid" while they are on OCs, and then lose it during the pill-free interval. Thus they have no gain over time, but nevertheless experience it as weight gain.
3) Change in body shape. It is possible that OCs change weight distribution in the body, which might be experienced as weight gain (because clothes fit differently) without an actual gain in weight per se.
4) We all tend to gain weight as we age. Also weight tends to fluctuate. So some may attribute that to OCs.
5) The studies didn't rule out a small increase in weight. Although the "weight" of the evidence found a lack of effect on weight there is some wiggle room in the final conclusion "...but no large effect is evident."
6) Some combination of the above.