title: Trend and variation in the seasonality of U.S. fertility, 1947-1976.
mesh_terms: D015068:17-Ketosteroids / Q000096:biosynthesis; D000328:Adult; D005260:Female; D005298:Fertility; D006358:Hot Temperature; D006801:Humans; D008297:Male; D012621:Seasons; D014481:United States
chemical_list: D015068:17-Ketosteroids