There is an increase in the prevalence of illicit opiate use among women of childbearing age in many countries today. Methadone is the treatment of choice for opioid dependency during pregnancy in the US because it markedly diminishes withdrawal symptoms and craving and blocks opioid effects, however, in utero exposure results in significant depression of fetal neurobehaviors such as fetal heart rate and heart rate variability and fetal motor activity, and significant neonatal abstinence syndrome (NAS) in the majority of exposed infants. Since its approval in 2002, the prescription of buprenorphine for opioid dependence has increased dramatically but, as with methadone, this mediation is not approved for use during pregnancy. Currently, women treated with buprenorphine prior to pregnancy are transitioned to methadone treatment due to a lack of information regarding the effects of buprenorphine on the developing fetus and infant. Pilot work by this research team suggests that buprenorphine- as compared to methadone-exposed fetuses display more optimal neurobehavioral functioning in the second and third trimesters of pregnancy. Although these results are encouraging, there is a critical need to explore fully the effects of this medication on the fetus and infant to adequately advise care providers and patients regarding its use. This is particularly true given the imminent publication of a pivotal study comparing buprenorphine to methadone treatment during pregnancy which has suggested the optimality of buprenorphine for the treatment of opioid dependence during pregnancy, and is likely to result in increasing numbers of women being treated with off-label buprenorphine during pregnancy. This proposal seeks to explore the effect of buprenorphine on maternal physiology and fetal neurobehavioral functioning longitudinally as a measure of the development of the fetal nervous system. Additionally, the neurobehavioral profile and NAS of the buprenorphine-exposed infant up to one month will be delineated in an effort to provide information necessary to provide optimal pharmacologic and non-pharmacologic treatment of NAS. Furthermore, this group has previously explored similar parameters in methadone-exposed fetuses and infants, and results of this study can be compared to those historical data. These parameters will advance our understanding of the way the investigators view and implement the future pharmacologic treatment of the opiate dependent woman during pregnancy and her infant after birth, and inform clinicians, health insurance companies and regulatory agencies in the provision of optimal care to the opioid dependent pregnant woman and her offspring before and after birth.