What if father is using heroine at time of conception?

No problem (for the baby, that is!). If the father is taking heroin and then contributes sperm to conceive a child, there will be absolutely NO effect on the fetus. While heroin use may be bad for mental/physical/emotional health and long- term stability of the father, the worst it will do will be to negatively affect his sex drive. But if he IS able to get it up, the sperm that eventually results will be exactly the same in every way as if he had not used heroin. Hope this helps.