As health care providers for pregnant women we always focus on making sure women are talking their prenatal vitamins and getting ample folic acid BEFORE conceiving to prevent neurotube (spinal and neural malformations) as well as avoiding an substances or medications that can affect or alter organ development which occurs during the first 12 weeks of preganancy.
This article discussing that opioid use during the last trimester of pregnancy actually decreases the volume of a neonate's brain by 5% and is probably related to issues regarding neurodevelopment of the child. While we currently focus on the withdrawl symptoms of the neonate from prenatal exposure, more research needs to be done looking at ongoing developmental issues, and delays of these children. Better work needs to be done to prevent these babies from exposure to these substances, including methadone for opioid addiction. Finally, further research is needed for meaningful early interventions to allow these kids to attain their full potential.
https://www.medpagetoday.com/pediatrics/generalpediatrics/115001