Diabetes mellitus in pregnancy will cause a bad influence on the mother, among others, with hidramnion pregnancy, toxemia gravidarum, infection, and ketoacidosis. The effect on the children, is a congenital disorder, respiratory failure syndrome, fetal death in utero, hyperbilirubinemia, macrosomia, hypoglycemia, and hypocalcemia. On labor may occur atonic uterus, uterine inseria, shoulder dystocia, stillbirth, termination of labor with action. This study aims to identify factors that influence maternal whether the occurrence of gestational diabetes mellitus. This study was an observational analytic study with case control method, the entire population is pregnant women who visited the hospital Goeteng Tarunadibrata Purbalingga in 2015. The sample in this study were all pregnant women aged over 24 weeks of pregnancy were divided into groups of cases are mothers pregnant gestational diabetes and control groups, namely pregnant women who did not have gestational diabetes. The sample size in this study was calculated using the formula rule of thumb and diadaptkan each group of 50 samples. Data were analyzed using Chi-square test. The results showed factors parity over a significantly (p 0.005) on the incidence of gestational diabetes mellitus, factors of recurrent infections was significantly (p