I would imagine it would be next to near impossible, and rather pointless, to do sufficient random studies into whether abortion always causes some form of psychological distress.
But for what it’s worth, I’ll post my experience. It’s only an anecdote, so pretty worthless in the scheme of things, but you might be interested to hear it.
I should point out that I’m atheist and largely pro-choice. I have also had bi-polar episodes and was hospitalised after an overdose following a rape (thought I was pregnant, but wasn’t or miscarried) when I studied in Russia in the early 90s.
I had an abortion 10 years ago and I was newly married. I never thought I wanted children (even though I was married, we neither of us wanted children then). I wasn’t ready for a child and felt an aching fear, resentment and was heading into a depression thinking about going through with having a baby.
Once I had the abortion I wouldn’t say that I was jumping for joy, but I felt relieved, clear-headed and able to get on with my life. I have never, ever, regretted that decision. It was the right one for me then (I do appreciate that Catholics view the embryo in a different light to atheists, so I can understand you won’t be able to empathize)
I managed to deal with my father’s suicide that happened just a few months afterwards, all the ups and downs that marriage and living can bring without falling into any serious depression since then.
I have since then (8 years later) changed my mind about wanting children. I had two back to back miscarriages (accidents), the last one of which left me infertile because of the treatment I needed.
I spent 3 years seeking help for this infertility and still, never once regretted my decision. I moved to SE Asia, found a fantastic doctor who operated successfully and I’m now 7 months pregnant (hence why I’m on here, for advice on childbirth from people who go through it frequently)
You may think I’m in denial. I’m not. To me, it was a potential foetus, not a life I was killing. It was unpleasant having to do it, but I take full responsibility for doing it. I’ve never felt depressed about it. I’m frank and honest about my decision and glad I had the choice.
I fully expect to get flamed out of existence for this post, but I thought you might want to hear a measured response from the other side, as it were.