I want to have a child with my best friend, is this a bad idea?

I have a best friend who I have known for almost 20 years. We were raised together because our parents are close. I am a woman and he is a man. We have talked and he has said he is afraid of raising a child with anyone who he isn’t in a relationship with. I am worried that even if we were in a relationship, it would put stress on the relationship and the child. The main reason I want to have a child with him is that I trust him and know that he is a good person. What are the negatives of raising a child with someone you are not in a relationship with?<br><br>Also, I am a little overweight, will that be a problem for my body during child birth?