By Genevra Pittman
NEW YORK (Reuters Health) - Black women were the most likely to gain weight while using a long-acting form of contraception, such as a hormone implant or intrauterine device (IUD), in a small new study.
Researchers found that during a year of using progestin-based long-term contraceptives, black women put on an average of four to six pounds, compared to a trend of slight weight loss or smaller weight gain for white and other women.
But Dr. Jeffrey Peipert, who worked on the study, cautioned against blaming the implants, injections and IUDs for the extra weight gain among certain women.
"Anecdotally, many doctors have had patients coming in and saying, ‘I'm gaining weight and I think it's my contraceptive method and I want to stop using it,'" said Peipert, from Washington University School of Medicine in St. Louis.
"People don't realize that the norm, while it may not be good, (is to) gain weight over time, and it may or may not be your method."
The findings are based on 427 women who were part of a larger study in which participants were provided with one of four types of contraception at no cost: a copper IUD or an implant, injection or IUD that delivers the hormone progestin over time.
How much weight women gained - or lost - varied greatly among those using each method, the researchers found. But on average, study participants put on more pounds while using the hormone implants or injections than a hormone-free copper IUD.
However, differences in age and race seemed to drive those variations, the team writes in the journal Contraception. They found that regardless of the contraceptive method used, black women tended to put on more weight than others.
Peipert said that could be due to differences in diet or exercise - not necessarily in how women respond to progestin-based contraceptives.
"There are many other factors that are involved in weight maintenance, weight gain or loss other than contraception. And these other factors probably are more important than the contraceptive method," he said.
Some researchers have believed progestin may slow down metabolism or encourage women to eat more, according to Peipert. But the new findings don't support a strong effect of the hormone.
"As a result of pregnancy, women tend to gain a lot more weight than they do from a contraceptive method," he said.
"My take-home message is, don't blame the contraceptive method."
SOURCE: http://bit.ly/ZhoEJu Contraception, online March 20, 2013.