Knowledge about maternal history is critical for guiding certain aspects of newborn clinical care as well as for research on neonatal issues. However, often the only maternal history available in the newborn record is in the clinical notes. We are using data from the MIMIC-II database for a clinical study on newborns admitted to the intensive care unit. Important maternal data were only available in the newborn notes, so we developed a simple algorithm to extract those data. We manually derived patterns for maternal age, gravida/para status, and laboratory results by reviewing a small set of notes. Using regular expressions and specific filters for notes and results, we extracted maternal data with recall of 0.91-0.99 and precision of 0.95-1.0 for the 289 infants in our study. Our methods could be used with other research datasets and with clinical documentation systems to extract maternal data into a more useful, structured format.