DR. WALLACE: My 20-year-old sister still lives at home with another sister and me. It so happens that this sister has always been a rowdy, wild, party-loving girl and now she is an unwed mother-to-be. She's four months pregnant and has decided against an abortion because the father told her he would marry her (some day) and that he would enjoy being a father. Our family considers this guy a loser and we think that my sister would be better off raising the child on her own.

My worry is not about my sister or the baby's father, but rather about the unborn infant. My sister has been a regular smoker of at least a pack of cigarettes a day for nearly five years, but do you think she would quit smoking for the sake of her unborn child? No, and that's her second bad decision of late.

I'm not sure it will do any good, but could you please print the damage that an unborn child can suffer when the pregnant mother smokes? I'll cut it out and tape it to the refrigerator so she will surely see it. (She eats a lot of snacks.) — Nameless, Toronto, Ontario.

NAMELESS: The damage a fetus can suffer when the mother-to-be smokes are extensive. According to "When a Woman Smokes," a publication of the Canadian Cancer Society, the nicotine and carbon monoxide from cigarette smoke can retard the baby's growth and cause it to be born below normal weight.

These small infants frequently have difficulty getting a good start in life, and their physical and emotional development during childhood may be affected. In addition, women who smoke during pregnancy are more likely to have a stillborn infant or a baby who dies soon after birth.

Your sister is lucky to have such a caring person as you in her corner who wants to be sure her unborn niece or nephew is optimally healthy.

RESTORE YOUR PARENTS' TRUST

DR. WALLACE: I'm a very unhappy and upset 16-year-old. Yesterday I absentmindedly left a personal letter from my boyfriend on the breakfast table. I had intended to take it with me to school and store it in my locker, but forgot to do so.

Well, wouldn't you know, my 12-year-old sister found the letter and read it. Then she gave it to my mom and now our house is in turmoil. My boyfriend wrote in the letter how much he enjoyed having sex with me and was looking forward to more exciting sexual adventures when he returns home from college.

My parents have written to my boyfriend and threatened him with bodily harm if he ever comes near me again. I have been told that I can never see my boyfriend again, and I have been grounded until further notice.

I really do love my boyfriend and I know he loves me and we were looking forward to a future together. It really bothers me that my bratty sister would read my personal letter and give it to my mother who would, of course, share it with my dad.

Now all I hear are lectures on unwed mothers and the growing menace of sexually transmitted diseases. I love my parents very much, but they are making me feel like a criminal. I'm really confused and I need your advice. - Nameless, Boston, Mass.

NAMELESS: Your parents are in shock. Discovering that their 16-year-old daughter is sexually involved with her boyfriend can only be described as traumatizing. Almost any parent would react in this way and their reaction is perfectly understandable.

I know this will be painful for you to hear, but your parents will never accept this boy as a suitable boyfriend for you. The image of him being your sexual partner is permanently seared into their minds. I'm sorry, but that's just the way it is.

You must accept your punishment and do not see this boy on the sly. You shouldn't have had sex with him, and you're lucky you haven't had physical complications. What you need to do now is to restore your parents' trust in you. I urge you to make this your top priority.

Dr. Robert Wallace welcomes questions from readers. Although he is unable to reply to all of them individually, he will answer as many as possible in this column. Email him at rwallace@thegreatestgift.com. To find out more about Dr. Robert Wallace and read features by other Creator's Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.