Is a doctor's assistance to a woman in an unlawful abortion forbidden (haram)?

It is not permissible to help this woman abort a prohibited pregnancy, as it constitutes cooperation in sin and aggression. Abortion without a legitimate Sharia-compliant justification is religiously forbidden, for it is the destruction of offspring and an aggression against a soul without right.

However, if there is a legitimate Sharia-compliant justification, such as a real danger to the mother's life, then abortion is permissible as a lesser of two evils, provided this is confirmed by a trustworthy doctor.

If the motive for abortion is that the pregnancy is illegitimate, this does not justify it; rather, it is the commission of another sin. And if it is after the ensoulment, it is a greater sin than adultery.