Unsure how to help

So, my aunt came to me looking for help with my cousin. My cousin has decided that she wants to become a mother, therefore is trying to get pregnant. Yes, my cousin is 24, and has a boyfriend, but everything isn’t how it seems. Here’s the background: my cousin had a stroke or seizure while being born. The doctors never knew for sure and just classified her under the cerebral palsy category. She did have other seizures during infancy, but eventually outgrew them during her childhood. She made wonderful strides in walking, learning, and talking. As she got older, her learning abilities never would catch up or progress further than 3rd grade to 5th grade levels. She graduated high school with a diploma and even had a drivers permit. Back to today: she always keeps up with people her age, even if her maturity level is a lot less. She’s included in a lot of things and has never been excluded or told you can never do this, until now. My aunt has talked to her until she was blue and told her that becoming a mother is something that is not in the cards for her at this time (but most likely never will be). When asked why she wants to be a mother, she states that all her friends are having babies, and her clock is running out. My aunt then reminds her that they have jobs, have husbands/partners, and can support a kid. My always fights back saying she can do what she wants and she will have a baby. I asked my aunt about birth control, as there aren’t many options for my cousin, due to medical and health reasons. The IUD is the only option that is ok for her. The problem is, my cousin refuses to get one, and knows she can, as my aunt didn’t get guardianship over her when she turned 18. There was no need to get it, as there were never issues like this. My aunt has also told her that she can’t live in their house if she has a baby (rules of the complex they’re in), and it would cause a financial and personal hardship on their family. Still, she doesn’t care. So my question is, has anyone ever experienced this with a friend or family member, or can someone give any ideas what to do in regards to talking my cousin out of wanting a baby? My aunt is open to any suggestions and I’m lost on what to do/say, as my cousin wouldn’t listen to me either.