My understanding is that Groupe Mutuel don't do travel insurance.
You need a provider like the ones suggested above - Allianz, Zurich Insurance, AXA-Winterthur.
It's a good idea to have travel insurance anyway, for any trips outside Switzerland, and the cost of insuring the whole family and paying each year is usually much better than insuring only when you are actually travelling. (And far better than forgetting to get insurance and then having a problem when outside Switzerland).
We have a policy which was added onto our home/contents insurance with Zurich Insurance. I think the cost to insure our whole family was around 120chf per year. I did need to claim once as my son and I got very ill the day we were supposed to travel with a stomach virus... the claims process was very straightforward and not a problem.
I do not know how they will approach the pregnancy problem, but I travelled at 32 weeks to China from Australia and there was no problem getting travel insurance to cover it...I just needed a form filled out by my doctor to say that I was fit to travel...and maybe it cost a bit more, I'm not sure.
Knowing how expensive health care can be in the USA, I would be very reluctant to travel there without good insurance to cover any possibilities...
The link for Zurich insurance is here: https://www.zurich.ch/en/private-cus...les-and-travel