Often the way Mannu has been ignored it seemed as if he was only used as a way to legitimise Ganga's interactions with Jagya and as some excuse or bridge to connect with Singhs. After all they first bonded over Mannu mainly.
Ganga is being unfair to Jagya also. A man needs to know what his wife is upto! Both parents of a child should know about decisions regarding the child. If it's unfair to terminate or prevent a pregnancy without knowledge and consent of parent then it is also not right to carry on with a pregnancy which is already said to be risky, without knowledge and consent of both parents.
Does she realise she'll be leaving Jagya and Singhs with more sorrow, guilt and burden if she dies giving birth to that child? Already Mannu's a handful for them. They'll handle Mannu and the newborn as well as other kids in family?
What's hiding this news getting her? She isn't even receiving the extra care which she should receive in this state!
She has already done a lot to repay Singhs. She doesn't need to do this.
And this callousness towards Mannu totally negates all that was shown in these months - about her fight to get him! Mannu was better off with Rat's parents then who wouldn't even mind running after him and who'd have treated him like a king!