The number and timing of stressors experienced during pregnancy were investigated using longitudinal data from the Western Australian Pregnancy (Raine) Study cohort (N = 2,900). Motor development data were collected at 10 (n = 1,622), 14 (n = 1,584), and 17 (n = 1,222) years using the McCarron Assessment of Neuromuscular Development. Linear mixed models were used to examine the effect of stress on motor development, accounting for repeated measures. Number of stressful events and mean Neuromuscular Development Index were negatively related (β = −1.197, p = .001). Stressful events experienced in late pregnancy were negatively related with offspring motor development (β = −0.0541, p = .050), while earlier stressful events had no significant impact.