Effects of a life-long high fat and high sugar diet (Western diet: WD) in ~38-day gestation guinea pigs. Pregnant life-long WD or control diet (CD) fed sows underwent T1-weighted and IDEAL water-fat images on a 3T MRI at mid gestation. Regions of interest were segmented around key volumes. The maternal liver volume and median fat fraction were significantly higher in WD relative to CD sows while measures of other fat depots were unaltered between diet groups. The fetal and placental volumes were not significantly different between the diet groups. This research expands our understanding of metabolically unhealthy pregnancies.