Gr 1 means placenta is close, Gr 4 means it's directly overlying/blocking the baby's exit -- high chance of preterm labor
; you'd need a C/S at 36-37wks. More common in woman w/ hx of C/S & smoking
. Not much you can do but wait. If dx'ed early, the uterus
still grows/stretches and a placenta can migrate away even in 3rd tri. Follow w/ US.