Pregnancy & Blood Type: Understanding Your Girlfriend's Concerns

Question
HELP ME PLEASE...MY GIRLFRIEND AND I SPLIT UP ABOUT 3 WEEKS BEFORE SHE FOUND OUT SHE WAS PREGNANT..SHE CALLED ME THIS MORNING AND SAID SHE WAS SEEING THE DOCTOR TODAY..SHE ASKED WHAT BLOOD TYPE I WAS? I ASKED HER WHY? SHE SAID THE DOCTOR NEEDED TO KNOW BECAUSE THEY HAD TO GIVE HER A SHOT..(SHE IS 6 MONTHS ALONG) SHE SAID IT WAS WHEN SHE DELIVERS WHEN THE BLOOD MIXES AND IT HAS TO DO IF SHE WANTS MORE CHILDREN!? I AM SO CONFUSED..IM NO DUMMY BUT STILL A NOVICE...WHAT IS SHE OR THE DOCTOR TALKING ABOUT? THIS MAKES NO SENSE...SHE IS VERY DISTANT AND WONT GIVE MA GOOD ANSWER..ITS SOUNDS LIKE A PATERNITY TEST...TO ME...AM I JUST PARANOID? IS THERE ANYWAY OF FINDING OUT W/OUT UPSETTING HER? THIS IS NOT HELPING THIS SITUATION...TO MUCH TIME TO THINK...WHAT WOULD YOU DO?
THANKS SO MUCH
PATRICK


Answer
Knowing your blood type is not any type of paternity test. Your former girlfriend, most likely, has Rh Negative blood. If the father of the child has Rh Positive blood, and the baby has inherited Rh Positive blood, the mother's body will recognize this as "foreign" and produce antibodies to the baby's blood. These antibodies can cross the placenta and cause the death of the baby or severe illness to the baby. It has nothing to do with paternity. If there is any doubt as to what the baby's blood type is, they should give her the shot at 28 weeks of pregnancy (7 months) and after delivery of the baby.  If they want to test for paternity, they will have to get a sample of your DNA(usually from a swab of the inside of your mouth) and also a swab from the mother's mouth. Then, if they want to know the paternity before the baby is born, an amniocentesis must be done to get amniotic fluid from around the baby. If they can wait until after the baby is born, they can test the baby.