We analyze the consequences of seasonal variation in maternal consumption on child health using two nationally representative Gambian household surveys. Seasonal fluctuation in consumption stems from difficulties borrowing when incomes are low during the rainy season and saving when they peak after harvest. The resulting fluctuations in maternal nutritional intake can affect birth outcomes and lactation performance. Using mother fixed effects to isolate the effect of birth season, we find that child health—measured by weight-for-age and height-for-age—varies significantly with birth timing. Children in farm households born during dry seasons (February-June) fare considerably worse than siblings born in other seasons.