Some lessons learned from genomic and epigenomic studies of the placenta.

Recent attention to the "replicability crisis" in research has led to greater efforts to outline research practices that might improve the quality of research results. Steps to improve replicability through standardisation and control of covariates can be field specific. In this review, we highlight lessons learned through our own and other genome-wide studies of genetic, epigenetic and gene expression variation in the placenta. We share our understanding of the impact of placental genetics, possible confounders, sources of sampling variation, dataset stratification, and adjustment for covariates. Overall, we hope to raise awareness of these study considerations amongst placental researchers.