4. From when does a woman carry the Halachic definition of a Yoledes:[1]

From when is a [woman] defined as a Yoledes [in the process of giving birth] to be allowed to desecrate Shabbos [on her behalf]? From when she sits on the birthing stool[2] [See Q&A for practical definition today], or from the time that the blood is drooling out [See Q&A for definition, and regarding breaking of the waters], or from the time that her friends [have to] carry her by her arms due to her not having strength to walk.

Once any of the above has begun to occur one is [allowed] to desecrate Shabbos on her behalf for all her needs which are able to be done now without delay[3].

Q&A

What is the practical definition today of sitting on the birthing stool? [4]

This refers to contractions[5]. Some[6] explain this to refer to the consistent set of contractions which occur before birth to open up the cervix, in which case one may desecrate Shabbos even if it is questionable if this will lead her to giving birth.  Others[7] question however if perhaps the contractions refer to those which come when one is ready to push the baby out, after the cervix has already successfully opened.

What is the definition of blood coming out? [8]

This does not refer to a mere few drops but rather to a nice surge of blood.[9]

May one desecrate Shabbos if the woman’s water broke?[10]

Some[11] have written that this is considered like a gush of blood coming out which defines her as a Yoledes, and one may thus desecrate Shabbos on her behalf from that time and on.

Others[12] however argue this claim and say it has no source, and it happens that the water breaks much time prior to the birth.

Others[13] say that if the breaking of the waters is accompanied by contractions then she is considered a Yoledes.

If one has not yet reached the above stage but a Doctor says that Shabbos must be desecrated for her may one do so?[14]

Yes.