As with most every other part of this thread, there is no right answer to that question without first really defining which meaning you are applying to the term "sentient".
Like life itself, sentience is a spectrum. There are things that are clearly sentient and other things that are clearly not sentient and in between a broad spectrum of types and ranges of things that are kinda sentient and kinda not sentient.
If a fetus (not yet a human) in the womb has a developed brain and nervous system (somewhere around the third trimester) it may exhibit some of the looser definitions of sentience, but certainly not full human sentience.
Anyone so limited that they can only spell a word one way is severely handicapped!