Given the direct effect of the herniated viscera on the ipsilateral lung, we hypothesized that right and left fetal lung growth rates are discordant in congenital diaphragmatic hernia (CDH) with a direct relationship to the degree of visceral herniation. To address this hypothesis, we compared right and left-sided lung growth rates (ΔLV-R, ΔLV-L) in varying degrees of visceral herniation. Lung volumetric measurements were reviewed from 58 isolated left-sided CDH fetuses undergoing MRI studies at both mid- (20–30 weeks) and late-gestation (>30 weeks) time points. ΔLV-R and ΔLV-L values (mL/wk) were then compared. The impact of the degree of visceral herniation (categorized to three groups: group1-liver down, group2-liver up with stomach in abdomen or left thorax or midline, group3-liver up with stomach in right thorax) on growth disparity between the right and left lungs was then compared using one-way ANOVA. Measurable growth occurred in both lungs between the mid and late gestational time points in each of the groups. The ΔLV-R exhibited a strong linear correlation with ΔLV-L (r = 0.625). However, the right lung grew significantly faster than the left lung (ΔLV-R = 1.36 vs. ΔLV-L = 0.17 mL/wk, P < 0.001). A higher degree of visceral herniation appeared to decrease the growth rate disparity with increasing limitations on ΔLV-R (P = 0.004). Collectively, these data reveal that the contralateral lung retains the potential to grow faster than the ipsilateral lung during the third trimester in cases of isolated CDH. Furthermore, a higher degree of visceral herniation places progressive limitations on contralateral lung growth thereby diminishing the disparity between the growth rate of contralateral and ipsilateral lungs. Lastly, measurements of total lung growth in the third trimester increasingly reflect the dynamics of contralateral lung growth in cases of isolated CDH. Supporting information for OC03.07, OC07.05, OC08.03, OC09.10, OC12.03, OC13.04, OC15.06, OC17.02, OC17.04, OC18.01,OC18.02, OC18.06, OC20.03, OC22.07, OC23.03 and OC23.04 can be found in the online version of these abstracts.