Aim: To determine if genetic variation associated with decreased dopamine neurotransmission predicts a decrease in motor development in a convenience cohort study of infants born extremely-low-birthweight (ELBW). Method: Four hundred and ninety-eight infants born ELBW had genome-wide genotyping and a neurodevelopmental evaluation at 18 to 22 months of age, corrected for preterm birth. A polygenic risk score (PRS) was created to combine into one predictor variable the hypothesized influences on motor development of alleles at seven independent single nucleotide polymorphisms previously associated with relative decreases in both dopamine neurotransmission and motor learning, by summing the number of alleles present in each infant (range=0–14). The motor development outcome was the Psychomotor Development Index (PDI) of the Bayley Scales of Infant Development, Second Edition. The linear regression models were adjusted for seven clinical and four genetic ancestry covariates. The mean PRS of infants with cerebral palsy (CP) was compared to those without CP. Results: PRS was inversely related to PDI (p=0.011). Each 1-point increase in PRS resulted in an average decrease in PDI of 1.37 points. Patients with CP did not have a greater mean PRS than those without (p=0.67), both with and without adjustment for covariates. Interpretation: Genetic variation that favors a decrease in dopamine neurotransmission predisposes to a decrease in motor development in infants born ELBW, but not to the diagnosis of CP. What this paper adds: Genetic variation in dopamine neurotransmission was associated with a decrease in motor development in infants born at an extremely-low-birthweight. It does not predispose to the diagnosis of cerebral palsy.