Objective To evaluate the Relationship between maternal and newborn endothelial function and oxidative stress. Methods Forty‐three pregnant women and their offspring were evaluated. As markers of endothelial function, the flow‐mediated dilation (FMD) was measured in pregnant women in the second and third trimesters, and nitric oxide (NO) was quantified in the endothelial cells of the umbilical cord vein. Malondialdehyde (MDA), as a marker of oxidative stress, was measured in the maternal plasma (second and third trimesters) and plasma from umbilical cord blood. Gestational age and birth weight were recorded. Correlations between variables were estimated, and adjustments were made for specific gestational week of measurement, gestational age at birth, and complications during pregnancy and/or at delivery. Results Maternal FMD at second trimester correlated positively with newborn MDA, although with marginal significance ( P = 0.090). The change in maternal FMD was positively correlated with newborn NO ( P = 0.039), although adjustment for gestational age and specific week of gestation attenuated this relationship ( P = 0.070). Maternal MDA at second trimester correlated positively with newborn MDA independently of gestational age at birth, specific week of gestation of the measurement, and having complications during pregnancy or at delivery ( P = 0.032). After adjustments, the change in maternal MDA correlated with newborn MDA but marginally ( P = 0.077). Conclusion Study findings suggest that under physiological conditions, enhanced endothelial function and/or oxidative stress in the mother may impact on normal fetal development. Future studies are recommended, employing larger sample sizes, a more extensive set of markers of oxidative stress, and comparisons of complicated versus normal pregnancies. Am. J. Hum. Biol. 27:822–831, 2015. © 2015 Wiley Periodicals, Inc.