Thats terrible. 4 children already and they remain ignorant of contraception. Some people in this (overpopulated) world are so selfish.

I still think that they look unprofessional  and second rate.

This sign does not surprise me...what does surprise me is the reaction by you guys..

Further implications- (if you choose to have children and assuming that your wife has a rhesus negative {for example, 0 negative} blood group), include the possibility that the baby will have a positive blood group.
If this happens, and the mother is not given appropriate Anti-D immunoglobulin, then there is a risk that the mother will have made rhesus antibodies. These antibodies do not affect the present pregnancy, but if your wife becomes pregnant again, these antibodies will 'attack' the zygote/embryo/fetus- usually resulting in a non viable pregnancy (miscarriage).
So essentially, the different blood groups will not affect the health of you or your wife- it could only potentially affect the viability of future pregnancies....
Hope this helps!