Birth Seasonality in Quebec, 1680-1799
Human birth seasonality is ubiquitous. Using over one million baptismal records in Quebec from 1680 to 1799, I show that the seasonal pattern of births exhibited a global peak in spring and a local peak in September. Over time, the magnitude of the spring peak declined, whereas the magnitude of the September peak rose. This pattern of births resembles the one in the 20th century from previous research. Using occupational and geographical data, I find that the pattern of births differed in social classes and locations. The magnitude of the peak in September magnified in the upper class in urban areas. Given the prohibition on family planning in Catholicism, I suggest an explanation from the seasonal work cycle. The high intensity of work in the fall correlated with a trough in the conception rate of the upper class in urban areas, and the relatively slack time in June and July during the farming season correlated with a peak in conception for the lower class in rural areas. The birth pattern was optimal, and it minimized the economic cost and the mortality risk. This study has established correlations, but the causal relationship remains a puzzle.