Use of the contraceptive Depo Provera appears to triple women's risk of infection with chlamydia and gonorrhea, a study reports today. 

An estimated 20 million to 30 million women worldwide use Depo Provera, which is injected into the arm or buttocks every three months. 

"It's popular among young women particularly," says Christine Mauck of the Contraceptive Research and Development Program in Arlington, Va. Not only is it convenient and effective, says Mauck, who wasn't involved in the new study, "it can't be found by your mother." 

But other studies have suggested that Depo Provera, as well as oral contraceptives, raise users' risk of contracting chlamydia and gonorrhea, two common sexually transmitted diseases. 

The study, which appears in the journal Sexually Transmitted Diseases, focused on 819 women ages 15 to 45 who were just starting birth control prescribed at two Baltimore-area Planned Parenthood clinics. About three-quarters were single. Of the women, 354 chose the pill, 114 chose Depo Provera and 351 opted for a non-hormonal contraceptive. The women were tested for chlamydia and gonorrhea after three, six and 12 months. 

By the end, 45 women had contracted chlamydia or gonorrhea. Women using Depo Provera were about three and a half times more likely to develop one of the infections than women using non-hormonal contraceptives. The researchers say they can't yet explain their finding. 

They also found that pill users were 50% more likely to become infected than users of non-hormonal contraceptives, but there were so few cases that could have been due to chance, says lead author Charles Morrison of Family Health International in Research Triangle Park, N.C. 

Morrison says one or two more high-quality studies are needed to confirm his findings. But, he says, the study does highlight the need for hormonal contraceptive users to also use condoms if they aren't in mutually monogamous relationships. Hormonal contraceptives alone don't protect against STDs, and, as this study suggests, Depo Provera might raise the risk of infection. 

Because researchers didn't randomly assign women to contraceptive methods, they can't be absolutely sure whether the Depo Provera itself or some characteristic of women who opted for it raised the infection risk, Mauck says. But the authors say it's unlikely that differences in the women led to the finding. 

The study was paid for by the National Institute of Child Health and Human Development and the U.S. Agency for International Development. 

TEXT OF INFO BOX BEGINS HERE 

Popular forms of birth control 

Use of Depo Provera, a contraceptive shot given once every three months, has been rising dramatically around the world. 

But the most recent U.S. data, nearly a decade old, show that this method lags far behind sterilization and the pill, which are still expected to top the list when updated data are released this year. 

Percentage of U.S. women using: 

* Tubal sterilization: 27.7 

* The pill: 26.9 

* Male condom: 20.4 

* Partner's vasectomy: 10.9 

* Depo Provera: 3.0 

Source: Alan Guttmacher Institute 

Rita Rubin 

 

Directions 

 

The above USA Today article, Contraceptive is linked to high STD risk Links to an external site.,  written by Rita Rubin, appeared in the Springfield News-Leader on Monday, August 23rd, 2004, on page 1A.  Please read it, then answer the questions provided in a pdf document.   

From the above article:  Describe the sample population in the study. 

• How many subjects are enrolled in the study? 

• What are their ages? 

• How many are single vs married? 

• How many partners does each subject have? 

• Have the subjects used birth control before? 

• How are they grouped in the study? 

Answer the following questions: 

1. What is/are the independent variable(s) in this research? (Think “potential cause”) 

2. What is the dependent variable? (Think “potential effect”) 

3. What term best describes this research— experimental, correlative, or descriptive? Why? 

4. Is there a control group present? 

5. What conclusions are reached regarding the outcome of the study? Is this an example of inductive or deductive reasoning?  Could other conclusions be made based on different interpretations of the data?  

6. Do you see any potential problems with the sample group, the way in which variables were organized, or the way in which this study was conducted? Would you have done anything differently? 

7. Is the author of this article one of the researchers, or someone who is knowledgeable in interpreting the scientific method (in other words, what are the author’s credentials?) 

8. Could more research on this topic be conducted as an experiment? Why or why not? 

9. The newspaper article you read is based on an article published previously in USA Today, which in turn is based on the original scientific study published in the journal Sexually Transmitted Diseases. Do you see any potential problems with the way the material is presented in the newspaper article?