Motile sperm concentration and total motile sperm count in ejaculates from donor candidates and accepted donors from 2017 to 2022. Marginal means ±95% CL are shown here for donor candidates (A, B) and accepted donors (C, D), from linear models accounting for age, Danish city, and monthly mean high temperature (see also Supplementary Tables S6 and S7). TMSC, total motile sperm count.