We relate mothers' children-related labor earnings losses, child penalties, to their location in the distribution of potential hourly wages. Using French administrative data and based on an event study approach, we show that the magnitude of these earnings losses decreases steeply along that distribution. This heterogeneity is the result of low-wage mothers leaving the labor market and more frequently reducing their working hours. By contrast, fathers' labor market outcomes do not vary upon the arrival of children, regardless of their location in the distribution of potential hourly wages.