DEAR DR. DONOHUE: A young couple I know wants to get married. His blood type is Rh negative, and hers is Rh positive. Would they have any problems if they decide to have children? – Anon.

ANSWER: Red blood cells come with identification bracelets on their surface. The A, B, AB and O blood types are one set of identifying markers. These markers are important when it comes to transfusing blood. Ideally people should receive the same donated blood type that nature gave them.

Another identification bracelet worn by red blood cells is the Rh factor. About 85 percent of whites, 92 percent of blacks and 98 percent of Asians and Native Americans have the Rh factor on their red blood cells. They are said to be Rh positive.

The Rh blood type is important during pregnancy. If an Rh negative woman becomes pregnant from an Rh positive man, the fetus can be Rh positive. Troubles are apt to arise if that is the case. (With your friends, this is not the case – the future mom is Rh positive, and the future dad is Rh negative.) Some Rh positive blood cells of the Rh positive fetus can find their way into the mother’s circulation.

Her body detects them as “foreign” and makes antibodies against them. Those antibodies enter the fetal circulation and destroy fetal red blood cells. That, in turn, can bring about a severe anemia, enlargement of the fetal liver and spleen, swelling of the fetal body and failure of the fetal heart. This reaction rarely happens in the first pregnancy, but it can be a major problem in future pregnancies.

Since the advent of RhoGAM, Rh incompatibility is not as big a problem as it once was. This material, given to a woman after delivery, suppresses her production of antibodies and protects future fetuses. In some instances, it is given before delivery.

DEAR DR. DONOHUE: My husband and I have successfully quit smoking by using Commit lozenges (nicotine replacement). My husband has been off cigarettes for 18 months, and I have been off them for three years. The problem is that we cannot stop Commit. We take six lozenges a day. Our dentist explained that, because the nicotine is not inhaled, we are fine.

We were both longtime smokers, and we were so happy to finally find a solution to quitting.

Do you have any suggestions? – A.P.

ANSWER: Your husband and you are to be congratulated for getting off cigarettes. However, you have traded a bad habit for a less bad one.

You’re not assaulting your lungs with nicotine, tars and the many other chemicals in cigarette smoke. You are, however, absorbing nicotine through the lining of your mouth. Nicotine has a bad effect on the heart and arteries. The Food and Drug Administration recommends using nicotine substitutes only for 12 weeks, at most.

Start tapering the amount of lozenges you use, and start today. If you decrease by one or even half a lozenge every third or fourth day, you would be off them in a relatively short time, and you wouldn’t suffer nicotine-withdrawal symptoms.

For readers: Commit is a brand name for nicotine lozenges. It helps smokers break the cigarette habit. A lozenge (LAHZ-inge) is a medicated tablet – in this case, a nicotine-containing tablet – that dissolves slowly in the mouth.

DEAR DR. DONOHUE: I believe I have genital herpes because my urine is cloudy. Three months ago, my urine test for infection came back normal. What other test should I have to detect herpes? – D.E.

ANSWER: Cloudy urine isn’t a usual sign of herpes infection. A painful outbreak of tiny blisters on the genitals is. A doctor can diagnose herpes by inspecting the rash, examining cells from the rash with a microscope, or sending a specimen from the rash to the lab to grow the herpes virus.

Cloudy urine sometimes indicates a urinary infection. You don’t have any symptoms of a urinary tract infection. Your cloudiness might be nothing more than phosphate crystals, a normal product of the body. If you want proof, get another urinalysis. Forget herpes.

DEAR DR. DONOHUE: I have a prolapsed bladder. It doesn’t bother me. Should I have surgery? Do sexual relations make it worse? – J.O.

ANSWER: A prolapsed bladder is one that has dropped down from its normal position, most often from a laxity of the supports that hold it there. Age and childbirth are two reasons why this happens. With a prolapsed bladder, a woman can lose control of urine and can have repeated bladder infections. You have neither, do you? If you don’t, you don’t have to rush to surgery.

Sexual relations do not make a prolapsed bladder worse.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com