'My brother's wife invited every niece and nephew to his birthday, except my baby.'

When a mum received an invitation to a weekend away with her family to celebrate her brother’s surprise 40th birthday, there was just one problem: her four-month-old daughter wasn’t invited.

While child-free events aren’t uncommon, the mother couldn’t help but feel she was being intentionally singled out when she realised that many other nieces and nephews – who were aged between one month and seven years – were invited.

Sharing her dilemma on parenting forum Mumsnet, the mum shared the heartbreaking reason why she felt her daughter had not been included.

“My brother and his wife have been trying to conceive for over four years,” she wrote.

"My partner and I have been invited but not my daughter as it's too hard for her [my sister-in-law] to see her."

The woman wanted to know if she was being unreasonable for taking the matter so personally.

Some commenters understood the woman's feelings of rejection, and said it was only natural to feel left out, especially since children younger than her own were being included.

LISTEN: What do you say to someone who's lost a baby? Post continues after audio. 

"Why does that not also apply to her side of the family?" one parent wrote. "If it's a 'no children' event fair enough, but it does sound like your daughter is being unfairly singled out."

But others suggested that there may be more to the story that could explain why the woman's daughter was being singled out.

"Any chance she could have been pregnant around the same time as you and had a [miscarriage]?" one asked.

"[That could be] why your child in particular is too painful for her to spend time with."

Some commenters who had struggled with their own fertility or pregnancy loss shared that unless a person has been through it themselves, it's almost impossible to know how seeing another's healthy baby could hurt so much.

"It will be truly horrific for her to see your baby, you really will never understand how awful [this] feels," one woman wrote.

"Small babies are very upsetting to see when a person is having fertility issues, especially if its a younger relation/friend who has had the child," said another.

"It will be too heartbreaking for her."

It's clear this is a difficult situation for both women, and at the end of the day, is it not only fair that the one sending out the invitations gets to make the decision they are most comfortable with?