I found unsolicited scan pics hugely triggering.
I'd come off social media when I was suicidal over being childless at 35...it was a really rough patch and it seemed like everyone was pregnant or had an adorable newborn. Christmasses were especially painful. All those Facebook announcements with scan pictures while you are feeling like an utter failure. So to protect my mental health, I came off. But it didn't stop the scan pictures being sent to me (or 30-40 adorable baby pics and videos at once when a baby arrived).
I'd often be sent scan pics privately on WhatsApp or Messenger...sometimes without any other message...just the scan pic. Then, "Did you get the pic Aunty Perky?!" if I didn't reply within 30 mins. Usually because I was sobbing in a heap as my period had just come. You could be so happy for a friend or relative but so disappointed in yourself...this awful chemical, hormonal, longing and feeling that you had utterly failed yourself (and your immediate family).
My best friend was going through struggles to conceive and confided in me that every scan picture her little sister sent her was a dagger through her heart, she'd cry for days etc etc - I explained I understood, shared my own experiences and how that visceral reaction to scan pics was doubly horrible as not only was it grief, it was shame and self hatred at my own body and my ugly emotion of envy. We cried together. Then 8 weeks later she did the exact same thing to me, "I know what we said about scan pics, but I know this time you won't mind the scan spam because it's me that's expecting!"
It's irrational, it's an ugly emotion...but it is very painful and unless you've experienced it yourself, you won't get it.
Most people won't get it either, because if they do sit and think about it, they may realise they inadvertently hurt a loved one or friend in the past.
However...
Sometimes we have to take responsibility to say, "I don't want to offend you but although I'm so happy for you, I find seeing scan pictures hard while I'm going through my own struggles to conceive. Please could you not share them with me?" We can't expect people to be psychic. Hopefully, enough people know that scan pictures can be difficult for women who have experienced involuntary childlessness, infertility, miscarriage, stillbirth etc. But I guess we can't assume.
Cue lots of MNers telling me I'm wrong and we can't police the sending of scan pics etc. No, we can't, I know.
And no. When it was my turn, I didn't share them. Some people asked, "have you got a pic?" and I would show them. If they said, "did everything go alright?", I responded with words, not pictures.