J. Greene and J. Touchstone conducted a study on the relationship between the estriol levels of pregnant women and the birth weights of their children. Their findings, "Urinary Tract Estriol: An Index of Placental Function," were published in the American Journal of Obstetrics and Gynecology (Vol. 85(1), pp. 1-9). The data from the study are provided on the WeissStats site, where estriol levels are in mg/24 hr and birth weights are in hectograms.