Sorry this comes from two posts, but I lost the first really long one I did. So I thought I would do them a bit shorter.
I am not surprised she miscarried and I don't want that to sound nasty. Alcohol and drugs and cigarettes (esp. cigs) are up there as a huge reason why women miscarry. Cigarettes can lead to stillbirth (the baby dies in the womb), cot death, chest and lung problems and low birth weight.
If your frind was ill and wne to the doctors, there would be very little medication that she could take safely as she is pregnant. In the 60's a drug called thalidomide was prescribed for morning sickness. Lots of babies were born with arms or legs missing. The drug was strictly recalled.
If a legal drug can cause that sort of damage to a baby, what could a an illegal street drug do to a baby? It could be mixed with anything.
There is a reason why medical drugs and treatments cannot be used in pregnancy. NOBODY knows the effect on the child.