Based on previous findings showing both better birth outcomes in migrant than in Spanish women and different rates of medical intervention according to mother's origin, we hypothesize that mode of delivery decisions to solve similar problems differ according to ethnic origin. Ethnic differences for maternal characteristics, medical intervention, and mode of delivery were evaluated in 16,589 births from a Maternity Hospital in Madrid (Spain). Multinomial logistic regression analysis was used to evaluate the effect of mother's ethnic origin on the mode of delivery, adjusting for mother's age, parity, gestational age, birth weight, and epidural anesthesia. Compared with the Spanish mothers, the risk of having a Caesarean section is significantly higher in Latin Americans and significantly lower for the Chinese. Both low birth weight and macrosomic deliveries are at higher risk for Caesarean section. The interventionist system characterizing Spain is being extended to all ethnic groups and, at the same time, different medical interventions are applied to similar problems depending on women's ethnic origin. Obstetric interventions might be contributing to the increasing trend of low birth weight and late preterm/early full term deliveries (37-38 weeks) observed in Spain. Behavioral and cultural values of the women and of the health care providers may contribute to systematic differences in labor management and mode of delivery.