Given the increasing availability of datasets such as the UK Biobank that (incidentally) include tens of thousands of genome-wide genotyped spousal pairs and large population biobanks with linked health record data for first-degree relatives, the offspring genotype-by-proxy MR approach could augment causal analyses of offspring perinatal exposures on their mother's outcomes as implementation is not restricted to datasets with mother-offspring genotype information.
Hatton et al. (Wed,) studied this question.