 Neonatal hyperbilirubinemia elongates hospital stay and may require treatment. The investigators noticed that bilirubin levels were higher among infants of primipara mothers than among multipara mothers. As this data is dichotomic and easy to produce, and may influence the maintenance, the investigators decided to find out if primiparity is a risk factor for neonatal hyperbilirubinemia. The investigators intend to collect data from patient files during one year, and compare the bilirubin levels and length of stay between newborns to primipara mothers and multipara mothers. 