Fig. 1.

Trends in birth weight from 1990 to 2005 among all 36,827,828 singleton births born at 37 to 41 completed weeks of gestation and by gestational age at birth among a low-risk subgroup of 502,716 singleton neonates born to mothers of non-Hispanic white race/ethnicity with 13 or more years of education and of married status, who received prenatal care in the first trimester, were non-smokers, had no pregnancy complications, delivered vaginally, did not have labor induced, had a prenatal ultrasound examination, and gained 26 to 35 pounds during pregnancy.

Donahue. Trends in Birth Weight in the United States. Obstet Gynecol 2010.