The mother that would have a procedure like this done discover late in their pregnancy that the unborn fetus could not survive outside their wombs for one [This is a run-on sentence because there is not a comma before the conjunction. Run-on sentences occur when conjunctions (and/or) and punctuation marks (commas and semicolons) are not used properly. ] reason or another.

Can some help me to fix this sentence

Is this what you were aiming at?

Mothers, who have this medical procedure done later in their pregnacy , may discover that the unborn fetus can not survive outside the womb.

Thanks I have struggled with the writing process.

Certainly! Here's a revised version of the sentence:

"The mother, who would have a procedure like this done, discovers late in her pregnancy that the unborn fetus could not survive outside of her womb for one reason or another."

In this revision, I added the required comma before the subordinated clause "who would have a procedure like this done." This separates the clause from the main sentence, making it clearer and easier to read.