Medical Assistance Question!?

I am on state medical assistance, only for pregnancy/ postpartum appointments.. now our baby is 5 weeks old and I got a letter in the mail wanting an in depth background on my fiancé since we live with him.. they want his social security number, work history, work’s insurance policy number, health history, etc (its like 4 pages long)

My question is why do they need all that info in order for me to have insurance? We aren’t married yet and I’m not seeking money from him. I don’t want them going after his checks or something but they want this info or will cancel my insurance and I may owe for past appointments. I live in MN if that makes a difference.. any advice!?