We hypothesized that fetuses with hypoplastic left heart syndrome (HLHS) have impaired growth compared to expected growth for gestational age. This is a retrospective cohort study including singleton fetuses with isolated HLHS identified from a single, referral center’s ultrasound database. To account for variable timing of ultrasounds, z-scores for gestational age were assigned for each biometric parameter. We identified 169 fetuses, of which 96 had more than one ultrasound. The median number of ultrasound evaluations per fetus was 2 (range 1–5). The mean gestational age at time of last ultrasound was 33.7 ± 4.3 weeks with a range of 20.4–39.6 weeks. While fetal growth restriction (11%) and microcephaly (3%) were relatively rare, mean z-scores at the time of last ultrasound for estimated fetal weight (mean difference z-score −0.20, p = 0.04) and head circumference (−0.28, p = 0.02) were lower than at the time of the initial ultrasound. Impaired somatic growth, defined as a decrement in z-score of 0.5 or more over time, was common (32%). There is a deceleration in somatic and head growth in fetuses with hypoplastic left heart syndrome that can be identified by routine ultrasound evaluation.