They get two jabs in this study so jabbed in first will very likely get jabbed in second or third. There will be very few cases in the "first but not second or third" group.
You’re misunderstanding the way I meant it.
If your first jab is in the 2nd trimester, that gives you ZERO information over whether jabs in the first trimester are liable to be harmful.
If you get a jab in the first, then the 3rd trimester, then if anything bad happens after the first jab, well, maybe the first jab did it; but the second jab is off the hook.