I am trying to find this one fanfic. From what I remember is the Sesshomaru goes into heat and rapes a female. Kagome finds her and the female is on death's door but before she passes she asks Kagome to take the her child into her womb and raise it.

It sounds like this one.

www.dokuga.com/fanfiction/story/10087/1

Hatred... or Something Else? by Rlmpcc110511

Based in an alternate world. Neither Sesshomaru, nor Kagome realize just how different their lives will be when Sesshomaru;s beast takes over and impregnates a random female. As Kagome raises the son of the Lord of the west and said female, together they must embark on a journey, that brings everyone's past to the front. Through war and hatred, can love be found.
Rating: MA - Universe: Alternate - Status: Complete - Category: Chapter Stories - Genre: Action, Angst, Dark, Erotica, Romance - Updated: 10-30-16 - Created: 01-09-16 Chapters: 61 - Reviews: 196 - Words: 246,696 - Reads: 301,308 - Anonymous Reading: Yes

That's it. Thanks