Fig. 3: Impact of sperm motility features on fertility.

a Boxplots of the motility features (VCL, curvilinear velocity; VSL, straight-line velocity; ALH lateral amplitude of head displacement; BCF, beat-cross frequency; VAP, average path velocity; LIN, linearity; STR, straightness; and WOB, wobble) grouped by their effect (either positive or negative) on fertility, according to model M3. Mean values (positive-negative) for each motility variable: ALH (3.94−3.26 μm), VAP (48.72−40.29 μm/s), STR (71.61−54.26%), LIN (39.60−28.49%), VSL (34.94−23.64 μm/s), BCF (10.03−10.14 Hz), WOB (54.50−48.52%) and VCL (90.80−79.19 μm/s). Mean comparisons between the two groups (two-sided unpaired T-student tests; number of samples per group: positive = 36482, negative = 32688) yielded a p value < 10⁻¹⁵ in all motility variables, except for BCF (p value < 10⁻³). Both groups met the assumptions of T-student test in all variables tested. b 11-cluster motility landscape showing the clusters with positive (light green) and negative (dark green) correlation with fertility, according to model M3. The high-density peaks (labelled with the cluster number) are also depicted, as well as contour lines to help visualise the stereotypes (as in Fig. 1).