Thanks for the query.
bowel movements will slow down due to hormonal
influence, leading to constipation
So because of that, the pregnant woman have to strain sometimes during defecation.
That can lead to injury
to anal mucosa, which can present with spotting.
Take plenty of water, fruits etc which will relieve constipation.
If the spotting repeats, better to consult gynecologist and with her advice go for laxatives and local analgesics.