did marilyn monroe have a baby??

No. But she wanted one badly. It is known that she had a conditon called Endometriosis. She had a couple of miscarriages as far as any one knows. If she ever had an abortion or more miscarriages, no one really knows except Marilyn. I think if she had a child, it would have been a beautiful baby. :)
Source: link
More info on Endometriosis: link

"The thing I want more than anything else? I want to have children. I used to feel for every child I had, I would adopt another." - Marilyn Monroe

I heard she wanted to have a little baby girl to call "beautiful" all the time because she said when she was little no one ever called her that. :(

No

Yes marilyn had a baby when she was 14 her aunt she lived with her husband raped marilyn/Norma and they was so ashamed they made her give the baby up for adoption. marilyn has a article about it she said he was a beautiful little boy and she wishes she could have kept him!

Se ela teve, como seria a aceitação desta pessoa, se já houve tantas desgraças. Sera que este filho correria algum risco, vocês protegeriam ele? Rezem por ela, pois ela precisa libertar-se de tantos infortúnios, ela foi uma vitima, todos nós amamos muito ela. Quem teria algum tipo de prova genética para que esse filho pudesse finalmente aparecer.