This is a study of quantitative nature with the aim of establishing the relationship between maternal position in the second period of labor and the condition of the newborn, infant as assessed by Apgar index. A descriptive cross-sectional study was designed, with an analysis of 8,538 live-birth deliveries occurring between 1996 and 2005 at a maternity school in southern Brazil. The analysis included data on all vaginal deliveries with the woman in a vertical (squatting) or horizontal (supine or semi-sitting) position, together with data on their unborn children and their rates of Apgar. There were 5,002 (58.6%) deliveries in the upright position, and 3,536 (41.4%) in the horizontal position. The mean Apgar rate at 1 minute was 8.11 for deliveries in the vertical position, and for the horizontal position it was 8.04 (p=0.009). For the maternal age 15 of 20 years, the mean Apgar rate in the first minute was higher in the vertical deliveries (p<0.001). When comparing the vertical and horizontal positions adopted by the mother in the second period of labor, better results were observed in the vertical position, and in adolescents this difference was more pronounced. Given the safety, effectiveness and high acceptability of this measure, it is urgent that the health services offer this choice of position to all pregnant women who have been elucidated as to the advantages/disadvantages.