 [ Symptoms ] how effective are latex condoms in preventing hiv [ Disease ] hello i have no idea why you would be told this informaiton certainly people do not check blood types before they fall in love the only blood type related problem that affects couples is related to the rh factor if the father of a child in a couple is rh positive and the mother is rh negative the mother can develop antibodies to the baby duing the pregnancy this is treated by giving any rh negative mother an injection of medication called rhogam once during the pregnancy at about 28 weeks and again within 72 hours of delivery laurie anderson rnp