What to do if you find out your teenager is pregnant
The words that are guaranteed to send a thrill through any parent are "mom, dad, you are going to be grandparents", unless, of course they are spoken by your 15 year old daughter at which point the thrill becomes a chill. Your first reaction is likely to be anger, which is totally natural, but unproductive. However, your teenager deserves your anger, they have done something that goes against all you believe you had taught them and they need to know that they have disappointed you.
The anger cannot be allowed to last if you are to handle this situation, it will sap you of energy, push your teenager away from you and destroy any chance you have of getting through this. The negative impact of a pregnancy on a teenager is significant; they are likely to do less well at school, have lower paid jobs, be less healthy than their peers and emotionally unstable due to the stress of the responsibilities of parenthood at an early age. The pregnant teenager desperately needs parental support however angry and disappointed you are, they cannot manage this alone.
There is the choice of abortion, but this will depend on your religious and moral beliefs and should be discussed with professionals and counselors. If you and your daughter disagree on this as a course of action, you need to be clear about what you are prepared to do. You cannot force your teenager to have an abortion, nor prevent them if they are determined. Ultimately it should be the child's decision, but they frequently make it based on emotional reaction, so a neutral, independent person may be the best person for them to discuss this with.
Then, you need to respect the decision your teenager comes to. This much harder if it is your son who is the father, as his girlfriend's parents will have the most influence and he may feel his wishes are not being considered. In either case, you need to talk to the other set of parents as soon as possible, and avoid any blaming of either child, it will not help and it may cause untold grief and anguish for the teenagers involved.
There are a lot of agencies who can help the family and the pregnant teenager through the months of pregnancy and beyond. Teenage mothers tend to have more medical problems, nutrition requirements and need more emotional support than older mothers. They are higher risk of depression and the radical changes they need to make can cause them to act out and get very angry with their family as the seriousness of their situation overwhelms them. Adoption is also an option and there are very good counselors who can advise on this. Do not try to deal with your teenagers pregnancy alone, the whole family needs support.