A compound called estriol is measured over a 24 hour period
in the urine of pregnant women. The baby's weight is then 
recorded at birth. Is estriol level related to birthweight?

Original Source: Greene and Touchstone (1963). 'Urinary tract estriol:
an index of placental function,' American Journal of Obstetrics
and Gynecology, 85:1-9.

These data were reproduced in:

Rosner (1982). Fundamentals of biostatistics, Duxbury Press.