The prevalence of obstructive sleep apnea (OSA) during pregnancy is rising. OSA during pregnancy has been associated with hypertensive disorders of pregnancy and gestational diabetes. The effect of maternal OSA on the fetus, particularly on fetal growth, is less apparent. Most of the currently available human data is based on non-objective assessment of OSA and includes heterogeneous populations with inadequate control on confounders, such as maternal obesity and pregnancy complications. Using objective tools in non-obese women with uncomplicated pregnancies, we aimed to investigate the association between maternal OSA and fetal growth. A total of 155 non-obese pregnant women were recruited. Birth-weight percentile of the newborns of women with mild OSA was significantly higher compared with the newborns of non-OSA controls (72% vs. 57%, respectively, P < 0.01). Birth-length and triceps thickness measurements were significantly higher among the newborns of women with OSA compared with controls (P = 0.02 for both). The proportion of large for gestational age (LGA) newborns was higher among women with OSA compared with controls (28% vs. 8%, respectively, P = 0.04). Our results suggest that maternal OSA during the third trimester of pregnancy - even in a mild form -is associated with accelerated fetal growth.