Strengths and limitations
The main strength of this study is the availability of a very large set of validated FFQ data. (21) Furthermore, to our knowledge, this study is the first to develop a nutrient specific screening tool with a minimal number of predictors that is applicable on an individual level while maintaining predictive accuracy. Finally, as this tool was developed in line with clinical needs, it is an evidence-based tool that should be relatively easy to implement in practice.
A limitation of this study is the use of dietary surveys, which could be prone to bias (22). Dietary surveys are primarily subject to underreporting (23, 24). We minimalized the effects of underreporting by eliminating FFQs with unrealistically low dietary intakes. Additionally, the Predict study is a tertiary hospital based cohort, and disease or medication related side effects can influence dietary habits, and with that calcium intake or uptake. Since calcium is absorbed in the small intestine, certain gastrointestinal (inflammatory) diseases or intestinal surgery can severely restrict calcium uptake. (25) However, the tool assesses dietary calcium intake, rather than uptake. Intake levels are unlikely to be affected by a reduced uptake. Therefore, there is no reason to suspect that this would influence the tool’s generalizability. We cannot think of any other indication for tertiary pregnancy care where calcium intake would be severely compromised, and therefore, we think our results apply to each pregnant woman, irrespective of underlying comorbidities or risks.