The Agent Provocateur model, 35, announced the news in a post titled "My Life's Dream" earlier this month on her blog for Spanish newspaper El Pais, reported Us magazine.
"I'm going to be a mother! I have managed to fulfill the dream of a lifetime. Because of that, I want to share with all of you this special journey and be able to tell you about all of my experiences during this fascinating time," Monica wrote.
Cruz then went on to say that although she would have preferred to wait for the man of her dreams before having a baby, she couldn't ignore her ticking biological clock.
"A 40-year-old woman is very young and she feels very young, but the maternity thing goes another way. It is measured with another clock that unfortunately we do not control," she explained.
"I've become very informed on the subject. It turns out that after 37 the possibilities of becoming pregnant decrease at an alarming rate."
Hence, Monica opted to take matters into her own hands. Though she initially hid out to avoid having to deal with speculation about the pregnancy, she's ready now to tell all.
"I've decided to talk about it: I have resorted to artificial insemination in order to get pregnant. I also wanted to talk about it because it is an opportunity to show my gratitude to all those anonymous donors that help a lot of women, like me, fulfill their lifetime dream."