Introduction Recreational Marijuana legalization has become more popular with each election season. Despite strong recommendations from the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists against the use of marijuana in pregnancy, use by this population is increasing. The 2016 National Survey on Drug Use and Health revealed that 4.9% of pregnant women 15 through 44 years of age reported use of marijuana, a 3.4% increase from the prior year Objective The objective of this study is to identify the rate of newborn exposure to marijuana in utero before and after recreational legalization. Methods Retrospective chart review of newborns 5 years prior to recreational marijuana legalization to the present. We included patients born at the Well Nursery and NICU at our tertiary care hospital who had a meconium positive for THC. Deidentified patient data was gathered and supplied by data abstractors. The total number of births was generated by review of monthly, internal, electronic medical record reports. Results Between January of 2014 and January of 2020, 320 newborns tested positive for THC in their meconium. The number of newborns found to be positive for THC per 1,000 live births was 5.0, 4.9, 5.5, 6.8, 8.0, and 10.6 year over year. Conclusions The number of newborns positive for THC has increased every year from 2014 to 2019 and has more than doubled over this time. The largest increase occurred between 2018 and 2019, which coincides with legalization of recreational marijuana. Newborn meconium is tested if their mother is positive for non-prescription drugs during pregnancy or at time of delivery. Because not all newborns are screened at birth, current data underestimates in utero THC exposure. Our study demonstrates a 32.5% increase in THC exposed newborns after recreational use of marijuana was legalized for adults, while total number of births at that time declined by 2.6%, suggesting pregnant women are more likely to use marijuana during their pregnancy after legalization of recreational use. This shows a need for further studies and educational interventions to warn pregnant mothers about the risks of marijuana use during pregnancy.