If there was cocaine use from weeks 18~27 but zero after that. will the babies poo when tested at birth show positive?

Meconium begins to: form between 12-16 weeks' gestation. Meconium testing can reveal maternal drug use during the last 4-5 months of pregnancy. Please disclose prenatal exposure to cocaine to your OB & pediatrician so they know to assess fetal/infant brain development by neuroimaging, then monitor your baby's growth & development, refer him/her to Early Intervention & refer you for treatment of your addiction.