I'm 40 and have begun to experience symptoms that suggest the early stages of menopause. I have been considering taking an over-the-counter natural estrogen replacement, but my husband and I are also considering having another child. Assuming I actually am still able to get pregnant, would a natural supplement designed to replace estrogen affect my ability to conceive? Would it affect the early stages of a pregnancy if I conceive while I am taking it?

D.R.

If you wish to find out whether you are entering menopause, a blood test for FSH on the third day of your cycle can determine your ovarian fertility potential. That should help answer some of your questions about whether you are likely to get pregnant and whether you should be considering menopausal treatments.

While there is a significant body of information regarding safety and efficacy of hormone replacement products, their ability to prevent bone loss and heart disease, and their risk of complications, no such data is available for the over-the-counter substitutes. Are they effective? Do they protect you against fractures and heart disease? Most over-the-counter natural products have not been tested for safety, and they are not subjected to an analysis of their manufacturing process. This means that quite often, the dose you receive in a tablet or capsule may have little to do with the amount of product the label states you will receive.

Just because these products are "natural" doesn't mean they are safe or even that they do not cause cancer. Rarely do we have reliable data on their effects. Do you really wish to experiment with your health and that of your baby?