For the ones who claim that Gauri truly wanted to win the hearts of her make believe in-laws and nobly thought the child would help in that wonderful goal, keep this in mind:
1) If you're trying to win someone's heart, would you yell at them for funding your education? Gauri traveled to the village and yelled at Bhairon for financing her medical education, as if he was doing something horrible to her.
2) If you're trying to win someone's heart, would you "challenge" them and say that you will win their child completely? Gauri challenged Sumitra that Jagat would never come back to them w/out her.
Therefore, it's safe to concur that she had no noble intentions of winning her make believe in laws' hearts and wanted an easy way to get into that haveli. In her mind, what's easier than a waaris?
And for the ones who kept saying Gauri was wronged in her youth... that child marriage was technically annulled. This is the equivalent of saying it never happened, and it spares them from badnaami. And despite what happened, Gauri was doing perfectly fine with her life and was on her way to become an independent doctor, something admirable. But instead she messed up her own life and is continuing to do so until she leaves Jagat.