In case of humans, there are four blood groups and two Rh factors. The major groups are O, A, AB and B, and the two Rh factors are positive and negative. Couples belonging to same blood group do not necessarily give birth to disabled babies. The disability could be because of various other reasons but not because of sharing the same blood group.
It is quite common to share same blood group for couples. Nothing bad can happen or is happening in child bearing activity by factors related to blood groups. Even though there are some minor blood groups such as M, N, etc. but they do not play any role in reproduction or blood transfusion.
Blood group incompatibility could be possible at times but not always. For example, in certain situations where husband is Rh+ve, wife is Rh-ve and the child in womb is Rh+ve, and there is mixing of fetal-maternal blood, then it may lead to abortion or abnormality in the new born. However, this can easily be prevented by giving the mother anti-D injections while she’s pregnant.
If you’re planning on conceiving you should know that complications related to incompatibility are extremely rare and even if you face them, there are proper medical solutions available today. Maintaining a positive attitude is more important here.
Child bearing is indeed a delicate process and affects the mother both mentally and physically. Seeking proper advice from medical professionals from time to time is extremely important. However, the most important thing is staying stress-free and physically sound.