Olivia Munn has struggled with breastfeeding because of "low supply"

In a series of posts on her Instagram Stories, she wrote: "Breastfeeding is soooo hard, especially if you have low supply...

"8 weeks in and I've taken a million vitamins, countless teas, lozenges, tinctures and worked with two lactation consultants. Breastfeeding. Is Hard."

In another Story, she shared a picture of her puppy cuddled up with her pillow, and quipped: "At least someone is making good use of my breastfeeding pillow."

Olivia also posted a poll asking her follows if anyone else was sharing her struggles, while over half of the people responding agreed with her.

She had asked: "Any other moms taking allll the supplements and teas and tinctures yet barely make milk?"

Olivia and John have been quite private about their personal lives since getting together, and Olivia's pregnancy wasn't announced by the pair until the 'Saturday Night Live' star made a surprise announcement during an interview on 'Late Night with Seth Meyers'.

When speaking about the past year, he said: "I packed a lot into this ... Is it September now? I went to rehab in September, I got out in October, I moved out of my home from my ex-wife [Anna Marie Tendler]...

"Then in the spring I went to Los Angeles and met and started to date a wonderful woman named Olivia.

"I got into this relationship that's been really beautiful with someone incredible. She held my hand through that hell, and we are having a baby, together.

"I'm gonna be a dad! I'm really - we're both really, really happy. I was nervous when I was about to say the news!"

Meanwhile, Olivia - who insisted she has decided to "pull back and to not play the game" when it comes to speculation about her relationship - previously admitted she was overwhelmed by the prospect of becoming a mother.

She said: "My brain hasn't been able to settle because it's just a constant feeling of you're doing it wrong.

"People tell me the baby will come and then you'll figure it out. But that doesn't stop the anxiety I feel right now."