Another idea would be to convert to airline miles and redeem as a ff award. Those tickets can often be changed at no cost within a year of ticketing.
Otherwise, there are a lot of trade offs we make in life. If you don't want to travel if you are pregnant, or it is a high risk pregnancy, maybe you should consider buying refundable tickets or postponing the trip.
From the way you are phrasing post #1, it sounds like you ultimately know it is a decision of trying for the pregnancy vs taking the trip. Pick the option that means more to you and make the decision accordingly.
Does SWA still have a no change fee policy? Haven't flown them in years.
Take care.