Fig. 1

Summary of methods and data contributing to this study. ^aAmong 176,897 women, 99.2% of them with sleep duration ranging from 2 to 12 h were included. ^bIn one-sample MR, the three and five groups of different duration lengths are based on thresholds from existing literature [1, 8]. We also split UKB women into thirds (N=58,483) as a sensitivity analysis to increase instrument strength and power in the longest duration group. ^cTwo-sample MR methods include: inverse variance weighted, MR-Egger, weighted median and leave-one-out analysis. ^dMultivariable regression analysis adjusted for maternal age at time of delivery, parity, education, smoking status in pregnancy, alcohol intake in pregnancy, body mass index before pregnancy and average household income. Abbreviations: ALSPAC, Avon Longitudinal Study of Parents and Children; BiB, Born in Bradford; MoBa, Norwegian Mother, Father and Child Cohort Study; MR, Mendelian randomization; SNP, single nucleotide polymorphism; UKB, UK Biobank