The use of assisted reproductive technology (ART) is a highly successful and widely employed modality for the treatment of infertility. In 2001, more than 40,000 infants were born as a result of ART therapy, which represents 1% of the births in the United States.1 Despite the success of ART, there is concern regarding both the safety of ART and its effect on maternal and fetal well-being. It is well-recognized that ART procedures significantly increase the risk of multiple gestations, both monochorionic and dichorionic, with the associated risks attributed to these pregnancies.2 Additionally, some studies have suggested an increased risk of chromosome abnormalities, low birthweight, and preterm delivery in singletons.3–6 Small studies have also suggested an association between the use of IVF and birth defects, adverse neurodevelopmental outcomes, preeclampsia, perinatal mortality, placenta previa, and an increased rate of cesarean delivery.7–13Data derived from ART registries only provide results for overall pregnancy outcomes such as birth weight and number of multiple gestations. Limited data are available to describe patterns of anomalies and other adverse obstetric outcomes.10 The few studies available are retrospective registry reviews, which exclude data regarding outcome with ovulation induction. Also, many prior studies fail to control for past obstetric history or other relevant variables. Our objective was to prospectively assess the effect of ART on the outcome of singleton pregnancies and to differentiate the effect of both IVF and ovulation induction.