Mom is type o+ and dad is ab+: is this abo incompatibility and is there a need for rogam coz she had a miscarriage for her first and 2nd preg..wat would be the probable cause?

Miscarriage &Rhogam: Rhogam is used only in rh negative mothers. This mother is +. A baby she carried would be a or b, and she could have high anti-a and/or anti-b antibody levels. If she did, that would be ABO incompatibility. It's not usually so severe. http://www.pregnancy.com.au/resources/topics-of-interest/postnatal/abo-incompatibility-in-newborns.shtml after 2 losses, she needs a high risk pregnancy specialist.

Unlikely the issue: Rhogam is unnecessary & only for Rh issues, not ABO. ABO "set ups" are rarely if ever a problem, causing at most minor treatable jaundice. Repeated fetal loss can be from as diverse issues as an incompetent cervix or a parent with a balance chromosomal anomaly. A consult with a perinatologist and a geneticist may be your best source of information. It would help if there was info on both losses.