In my neighborhood pool, mothers often bring their four- and five-year-old sons into the women's changing room. This seems to me not to be in the best interests of the child. In fact, I think it's a subtle form of sexual abuse. I'm sure we wouldn't bring our five-year-old daughters into the men's locker room. At what age should parents stop bringing their children into a dressing room of the opposite sex?
The proper age to stop bringing children into a dressing room of the opposite sex is when a mother can clearly see that her child is starting to feel uncomfortable. But since, such signals are hard to read in these circumstances, I would err on the side of caution and stop between the ages of two and three.