Have any other adoptive parents struggled with the issue of accepting prenatal exposure to drugs, tobacco, alcohol, medications?

My husband and I are hoping to adopt an infant through open adoption. We have been in the “waiting pool” for about a year. My question is: have any other adoptive moms or pre-adoptive moms struggled with the issue of accepting prenatal exposure to drugs, tobacco, alcohol, medications? On our screening form we listed the level of exposure to substances that we are open to in a birthmom, but we were relatively conservative in our choices (that is, no exposure to hard drugs, up to moderate cannabis and cigarettes, up to mild drinking, that kind of thing). I’m worried that we’re being too conservative in this way and therefore limiting ourselves, as at our agency, birthmoms whose prenatal substance use doesn’t match our choices do not see our profile. This policy is to prevent disappointment in a birthmom who might choose an adoptive family only to find that they aren’t open to her level of substance use. I’m curious about the experiences of birthmoms and adoptive moms in this realm. What level of use of tobacco, cannabis, alcohol or other drugs is very risky for the health of the baby? What level is less risky?