How long does heroin stay in a fetus blood?

Heroin can cross the placenta and affect a developing fetus, with its metabolites detectable in fetal blood typically within a few hours after maternal use. The duration that heroin remains in fetal blood can vary, but it is generally detectable for several hours to a couple of days, depending on factors such as the amount used, the timing of use, and the individual metabolism of both the mother and fetus. Chronic maternal use can lead to longer-lasting effects and withdrawal symptoms in the newborn.