Quoting MommaSav2:" Is it possible to relactate during pregnancy? My milk was dried up, I haven't been able to squeeze any ... [snip!] ... questions are could i have relactated or is this probably colostrum? And should the weak contractions during nursing worry me?"
no, I don't think you can "truly" relactate WHILE pregnant. however, it's probably your colostrum coming in a bit, as you supposed.
the uterus contracts when you nurse / your nipples are stimulated. that is normal and should not be a concern during pregnancy unless you are already at high risk for premature labor.