With every new, world-altering tech, there comes a moral panic. When the mechanized loom was invented, Luddites smashed them, fearing (with some justification) that they would lead to unemployment. When Alexander Graham Bell invented the telephone, people feared that they could transmit evil spirits, or that it would be the end of face-to-face socializing as we know it.
And when the train took off, people feared that women's uteruses would shoot out of their vaginas if the vehicle should go above certain speeds. Yes, in a sort of vaginal "reverse Speed" situation.
Of course, it's understandable given that for centuries people could only hope to make it from Londinium to Ierusalem in 53.5 days, that people had concerns about new technology that could hurtle you over the ground at speeds of up to 16 kilometers per hour (10 miles per hour). One concern, written about some years later in the Lancet, was that "the immense velocity (for some rash speculators had hinted at a pace of [32 km/h] twenty miles an hour) was fraught with danger to the respiration, and the carbonic acid generated by the fuel when passing through long tunnels would inevitably produce suffocation by 'the destruction of the atmosphere'."
They envisioned a time when "boiling and maiming were to be every day occurrences," which is a lot more dramatic than the reality of trains turning up late, and not being able to find a seat. However, when the boiling and maiming happened, you probably wouldn't be too concerned, given that you were dealing with the much more pressing matter of your uterus sliding out of your vagina.
Cultural anthropologist Genevieve Bell told Wall Street Journal TECH that people believed that should trains go above 80 km/h (50 mph), "uteruses would fly out of [their] bodies as they were accelerated to that speed”. A thing that if it existed, you'd have noticed during your commute.
Though we couldn't find reference to the specific speed referenced above, it seems even physicians of the time had concerns with regard to women's bodies (likely tainted by a large helping of sexism), including the idea that her uterus would shift around and dislocate if she travels by boat or train just before her period.
"If a woman sets out for a sea voyage or a journey by rail the day before her menses should appear, she will be very apt to skip one period, and perhaps more. Or, if the flow comes, she may experience greater suffering than usual. If it be too scanty, or too profuse, she may be very ill. As an indirect consequence, she will be likely to suffer from some form of uterine flexion or dislocation," one physician writes in the New England Medical Gazette, quoting a second doctor for good measure that "a displacement of the uterus is just as much an absolute fact as the occurrence of a hernial protrusion."