Estimating energy and nutrient intakes in studies of human fertility.

Two methods of dietary recording, the 24-hr recall and the weighed dietary intake methods, are considered appropriate for estimating energy and nutrient intakes in studies of human fertility. The former method gives lower estimates than the latter, although weighed intakes may underestimate true intakes. Examination of food intakes of pregnant, lactating, and non-pregnant, non-lactating New Guinean women shows their diet to be less homogeneous than is generally assumed for groups in developing countries. As a result direct observations of food intake for a limited number of days are not sufficiently accurate for the estimation of intake of most of the nutrients examined. Rather the study design should reflect the variability of intakes of the nutrients and groups under consideration.