Yes TOS is more prevalent in females than males.
There is probably a study somewhere... but I think it is due to the narrower shoulder chest area..

carrying a kid around or even propped on your hip will make for some slight body changes that may aggravate TOS.

If hypermoblie even more so.

[TOS is more common in women than in men. The sex ratio varies depending on the type of TOS.

* The female-to-male ratio in neurologic-type TOS is approximately 3.5:1.
* The venous type is more common in males than in females, and the arterial type has no sexual predilection.]
http://emedicine.medscape.com/article/1143532-overview