Hi,
As mrsjb says, it strengthens and tones the muscles of the uterus.
I know many people seem to be told to only take it really late in pregnancy, but they have qualified herbalists in Neals Yard, and they advise taking it from 6 months in pregnancy to get the full effects. I did this with my son (he was only 3 days early), and I'll be doing it this time too. I did still have a 37 hour labour, but I managed to get fully dilated, so had an assisted delivery rather than a c-section. The midwives were surprised I managed to get to fully dilated as the contractions stayed at 5 mins apart, so maybe the raspberry leaf tea helped.
xx
21+1