Sex ratios of the offspring of patients with multiple sclerosis.

The sex ratios (proportions male) of the offspring of both male and female MS patients produced before disease onset are similar, and closely approximate Caucasian live birth sex ratios. The sex ratio of the offspring of male patients sired after disease onset is significantly lower than these values. In contrast, the sex ratio of the offspring born to female patients after disease onset is non-significantly higher. In short, MS patients produce unusual offspring sex ratios only after disease onset. It is suggested here that they do so as a consequence of a stress-induced reduction in testosterone levels in male patients, and possibly a stress-induced increase in testosterone in female patients. In any case, the data suggest that the sex ratios are a consequence of the disease and not a key to its cause(s).