The original mission of the Fels Research Institute included the serial study of individuals before birth; this aspect of the mission has not been neglected. Particularly during the early years of the Fels Longitudinal Study, strenuous efforts were made to perform prenatal studies and successes were achieved although the available technology allowed only a narrow range of investigations. Better methods are now available that could assist prenatal studies of growth, maturation and body composition, but some involve radiation (computerized tomography), and others are expensive (ultrasonography, magnetic resonance imaging). Imaging procedures have not been applied serially in normal pregnancies although these studies have great potential.

Some investigations made within the Fels Longitudinal Study that relate to the fetal period are described with physical growth (Chapter 4) and skeletal and dental studies (Chapter 6). The prenatal investigations described in this Chapter have been grouped under the headings: prenatal studies, and familial and genetic studies.

Prenatal studies

Diet and nutrition

During the 1930s and early 1940s, the relationships between prenatal maternal diets and the size of the infant at birth were studied. This was a Herculean task. Daily dietary records were kept by 205 mothers for 4 to 7 months. These mothers were not given dietary advice; this was a ‘natural experiment,’ as is generally true for the observations made in the Fels Longitudinal Study. These, and other dietary data, provided some important information.