I believe you would have to wait until the baby is born, unless things are so much more modern now days. What's the rush? To find out who the baby belongs to? or Medical concerns. If it is who the baby belongs to. you can go to Blood Types and there is a place there you can go to , to put mom and dad's blood type in, and it will tell you what the baby should be. Or to find out which guy is the dad & the baby is born you can take Mom and babies type and put it in and find out choices of what the dad needs to be. Good Luck.

Suggest you get prenatal care ASAP & 1st visit should do blood test screening.
see this link


http://www.medlineplus.com
Also, please be sure to ask a OBGYN DR, nurse or Practitioner.

Remember you should have prenatal care.

This probably reached you late, but good luck!