Answer
In this observational study, there is a confounding variable, which is the tendency for a woman to take care of their health and be cognizant of their physical health. As such, women who exercise regularly are less likely to have spontaneous abortions because they are less likely to exercise while pregnant. On the other hand, women who exercise while pregnant are likely to have more spontaneous abortions because they are less likely to follow the instructions of their doctors and take care of their physical health while pregnant.
Work Step by Step
1. Consider the difference between the groups of women undergoing spontaneous abortion more and less frequently.
2. Identify whether that difference is causative or confounding.
3. Since women who exercise are healthier overall, the difference between the two groups in confounding and not causative.
4. Therefore, women who exercise while pregnant are less healthy overall contributing to the increased likelihood of spontaneous abortion.
