A data frame with 21 observations on the following 4 variables.
Age
the gestational age in weeks;
a numeric vector
Births
the number of births;
a numeric vector
Weight
the mean birthweight in kilograms;
a numeric vector
SD
the standard deviation of the birthweight in each group in kilograms;
a numeric vector
Details
The gestation time for 1513 infants born
in St George's Hospital, London, to Caucasian mothers willing to participate
between August 1982 and March 1984.