"I gave up my son for adoption 31 years ago. This is what I want him to know on Mother's Day."

Catherine* was 21 when she discovered she was pregnant.

It was an accident.

When she told the father of the baby, he announced he was going overseas, and would be away for the birth. Catherine, now 54, gauged it was also unlikely he would be around for her and the baby when he returned. In fact, she was fairly certain he was seeing someone else.

“I think I was in denial for the first couple of months,” she says. “So by the time I thought about making a decision about whether to terminate, it was too late. I think I may have done that on purpose subconsciously… procrastination took the decision away from me, then there was no turning back.”

For Catherine, almost 30 years ago, a single parent family wasn’t an attractive option. “I could see I would end up as a single mum and I didn’t want that,” she says. “So as soon as I told my parents, I announced I was going to give the baby up.”

While she acknowledges her ideas have shifted since then, she says she thought at the time that “a single parent family was a ‘lesser family,’ and I wouldn’t be able to provide what a child needed”.

Catherine recalls feeling very strongly that a baby would be “disadvantaged” with her, and “would not have as good a life with me as with two parents”.

For the next several months, she spent most of her time at home. A select few friends and family knew she was pregnant, but she didn’t want everyone to know. She wanted to be able to get through the pregnancy, give her child up for adoption, and move on.

I asked whether once she gave birth and saw her child, it was painful to give him away.

"It was..." she said. "But at the same time I think I was prepared. It was my choice and I had detached emotionally I think."

"I had convinced myself that I had made a mistake, and the way to fix it was to give this child a chance with a mum and a dad who really wanted a child."

Over the following weeks, months and years, she never second guessed her decision. "It may be weird," she said.

"There was no doubt in my mind that being a single mum was bad for me and bad for a child. I think I had a fear of a poverty trap, and of labels..."

In the years following the adoption, Catherine's mum would mark the boy's birthday with a card. It was an unspoken acknowledgement.

Now, on Mother's Day, Catherine often finds herself wondering about her son. She's never contacted him, he's never contacted her, and she has no idea who he is.

"I wonder if he is happy," she says. "I have a very strong feeling that he is. By now he may have his own kids and that makes you curious."

Catherine says, however, that it's hard to think about him, because she doesn't know anything about him. She doesn't know what he looks like or what he does. So she finds herself thinking about her own experience with him instead.

"It is weird," she says, "that I never think he is not alive, and yet he may not be".

One of her biggest fears is that he has been trying to find her and can't. She describes it as "distressing". But she says she has a feeling that isn't the case. It's a certainty she can't quite describe.

In the last few years, as her own children have grown up, she's started to consider making her details available so he can contact her if he wishes.

"I think it is up to him," she says. "I made the choice. I don't want him to forgive me or anything. I want what he wants. I did it for him."

This Mother's Day, Catherine, who will celebrate the day with her husband and their three children, has very simple wishes for her son.

"I hope he is a good person and that he has had a lot of love in his life," she says. "I really hope he loves his parents."

For many women on Mother's Day, there are stories we can't necessarily see. There are struggles with infertility, miscarriages, the tragedy of losing one of your children, and the complexities that come with adoption.

Mother's Day is for them, too.