Aim

To investigate if maternal caffeine intake during pregnancy causally influences offspring birth weight using a Mendelian randomization approach.

Hypotheses

A recent meta-analysis of observational studies found evidence that caffeine consumption during pregnancy is associated with increased risk of having a low birth weight baby [1]. However, it is not clear whether this association is causal or whether this may be due to confounding by other lifestyle factors. For example, coffee consumption is positively correlated with cigarette consumption, a known risk factor for low birth weight [2].

This problem of confounding can be minimised using Mendelian randomisation analyses, whereby genetic variants associated with caffeine are used as proxies for measured caffeine consumption. Genome-wide association studies have identified 8 independent genetic loci associated with coffee consumption [3, 4]. Some of these variants have been shown to associate specifically with caffeinated beverage intake in ALSPAC [5].

This project will investigate associations between maternal caffeine-related genetic variants and offspring birth weight using a Mendelian randomisation approach.