Section 91 IPC
91. Exclusion of acts which are offences independently of harm cause.—The exceptions in sections 87, 88 and 89 do not extend to acts which are offences independently of any harm which they may cause, or be intended to cause, or be known to be likely to cause, to the person giving the consent, or on whose behalf the consent is given.
Causing miscarriage (unless caused in good faith for the purpose of saving the life of the woman) is offence independently of any harm which it may cause or be intended to cause to the woman. Therefore, it is not an offence “by reason of such harm”; and the consent of the woman or of her guardian to the causing of such miscarriage does not justify the act.