File photo: The 55-year-old actress and her husband Mattia Dessi welcomed daughter Frida into the world last month. Picture: AP

Brigitte Nielsen had been planning to have another child from the age of 40.

The 55-year-old actress and her husband Mattia Dessi welcomed daughter Frida into the world last month, but she admitted it has been a "long road", including freezing her eggs shortly after she met her spouse 15 years ago and undergoing over 10 years of IVF treatment.

she said: "It is such a long road. What I want women to know is that everything is possible, but you have to be realistic.

There is a huge disappointment. If you do IVF, 80 percent of the time, it doesn't work. It's that phone call going, 'It's negative.' It's the waiting. It's a lot. It's a big, big journey."

And Brigitte - who was given just a 3-4 percent chance of conceiving with her own eggs - admitted it has been an "expensive" journey to later-life parenthood.

She told People magazine: "Another thing is it is expensive. It doesn't come easy or cheap if you do it my way. I want people to know that."

The Red Sonja actress found it helpful to learn as much as she could about the process and now considers herself an expert in fertility treatment.

She said: "You want to be in good hands. You don't want to just go with some doctor.

"Be careful with who you choose and [make sure you have] a good relationship there, someone you can talk to. Do you feel protected? ... Study what you're doing with your own body. I read so much. I could probably work in an IVF clinic right now."

The Beverly Hills Cop II star has called for more women to speak about their fertility struggles because it can be a "lonely" time.

She said: "I think at times you can feel lonely, because a lot of women don't talk to each other about it. We should hold hands because there's nothing wrong with wanting to have a baby whether you're 20, you're 30, you're 40 or, in my case, 50."

Brigitte understood why she faced criticism for wanting a baby in her 50s but she is happy with the choices she and Mattia, who is 15 years younger, have made.

She said: "Some women think, 'Oh my God, I'm too old.' Well, yeah, I can understand people saying, 'How dare she?'

"But how many men have their first kids in their 60s and 70s and they never doubt it?

"Do I understand that [people] are a bit skeptical? Yes, I understand. I also totally respect the fact that not everybody likes it and agrees with it, but it is my life.

"It [is] his first baby and we are very much in love. We are very happy.

"We have a solid relationship. We are celebrating, or we have already - 14 years together."