The purpose of this study is to evaluate the effects of drugs used by treatment providers on the fetuses and infants of opiate dependent women. The subjects in this study are women enrolled in a large, multi-site, double blind study that looks at the effects of methadone and buprenorphine treatment during pregnancy. This study will evaluate fetal and maternal biophysiologic data longitudinally during pregnancy to determine how these substances may affect fetal neurobehavior. Additionally, infant neurobehavioral assessments and measurements of infant vagal tone will be collected to see how methadone and buprenorphine differentially affect the neonatal abstinence syndrome, or "withdrawal" in exposed neonates.

Previous research by this group has found that methadone treatment during pregnancy directly impacts fetal neurophysiology independently of maternal physiology. Buprenorphine is a new therapy for opiate dependent individuals, and its use during pregnancy is currently being evaluated. Some research has shown that buprenorphine lessens the neonatal abstinence syndrome when compared to methadone. Thirty methadone and 30 buprenorphine maintained women will be evaluated at 24, 28, 32 and 36 weeks gestation using a state-of-the-art computerized fetal actocardiograph and data analysis program to simultaneously evaluate fetal movement and heart rate and maternal physiologic parameters. Investigators will be blinded to treatment group. Longitudinal neurodevelopment of the fetuses in each group will be explored. The differential effects of methadone and buprenorphine on the neonatal abstinence syndrome will also be explored.

Inclusion Criteria:

• generally healthy opiate dependent women
• currently enrolled in the study "Maternal Opioid Treatment, Human Experimental Research study
• uncomplicated singleton pregnancies

Exclusion Criteria:

• complications of pregnancy, including HIV, diabetes, polyhydramnios, hypertension, preterm labor or placenta previa
• evidence of fetal malformation
• significant maternal health problems, including HIV infection
• significant maternal psychopathology that would preclude informed consent, including schizophrenia
• alcohol dependency per DSM IV criteria

Opioid dependent pregnant women enrolled in parent study (Maternal Opioid treatment: Human Experimental Research)