That's a surefire way to homelessness, unless you are very (SV engineer or doctor) rich.
That has zero to do with whether it is safe to move into in-laws house when you are entering vulnerable period of pregnancy and being primary caregiver for small kids. Because both severely limit your economic options even in best conditions.
That is generally only true until kids are in the picture, then the famous "what is best for the child" over rules all
Family courts take stability of the child over all else, so if the child is used to living in the family home who ever the custodial parent is will get possession of the home even if that custodial parent was not the owner of the home before the marriage
A house that was sole property before the marriage, remains sole property after the marriage, even if the other spouse is added to the deed. The other spouse only takes a "equitable interest" to the extent that marital resources, or their own separate resources, are invested in the house. This is the case in community property (like CA) and non-CP states (most of the rest).
The primary issue is that in some states the presumption changes when the spouse is added to the deed, so that the house is presumed to be marital property in the event of divorce until the pre-owning spouse shows that it is not. (But in most states, there is no presumption and the other spouse must show that they have an equitable interest in the house, generally by showing that marital resources were spent to pay the mortgage or make improvements.)
But usually such opinions are fairly controversial, which suggests a clash of deeper underlying values.