The 35-year-old lingerie model shared the happy news on her blog.
"I am going to be a mother! I have managed to fulfill the dream of a lifetime. I want to share with all of you this special journey and to be able to tell you about all my experiences during this fascinating time," Monica said.
The model said that she was worried that she wouldn't find the perfect man in time to start a family, so sought help through artificial insemination.
"I want to show my thanks to all those anonymous men that help to give many women like me, the dream of their lives," she added.
A celebrity in her native Spain, the brunette decided to announce her pregnancy before the flood of inevitable questions she would get about the identity of the father.
"I wanted to avoid, above all, that they spoke about possible fathers or the possible candidates to be it," Monica said.