OBJECTIVE: Neonatal polycythemia has a complicated etiology, for which monovariable analysis was generally used in the most previous studies.This paper investigated the independent risk factors for neonatal polycythemia by multivariable analysis and studied the interactions between the risk factors. METHODS: A case-control study was conducted to investigate 27 potential risk factors for neonatal polycythemia. These risk factors were significant in monovariable analyses and were selected for the non-conditional logistic regression analysis. The interactions of the risk factors were evaluated using an additive model. RESULTS: Monovariable analyses showed that pregnancy-induced hypertension syndrome, fetal asphyxia, fetal distress, small for gestational age, premature rupture of membranes, premature birth, placental abruption, multiple pregnancies and low birth weight were significant(P<0.05).Non-conditional logistic regression analysis indicated fetal asphyxia (OR=7.8255), premature rupture of membranes (OR= 2.7007),pregnancy-induced hypertension syndrome (OR=2.8313),premature birth (OR=7.7394) and low birth weight (OR=7.4803) as independent risk factors for neonatal polycythemia.The interaction analyses showed that there were positive interactions between low birth weight and small for gestational age, low birth weight and fetal distress,as well as premature birth and small for gestational age (synergy index>1). CONCLUSIONS: Risk for neonatal polycythemia is multifactorial. The coexistence of multiple risk factors may increase the incidence of this disorder. Clinically it is important to monitor and manage all potential risk factors.