preferred_name: Twin gestation, monochorionic/diamniotic (one placenta, two amniotic sacs)
preferred_name_lc: twin gestation, monochorionic/diamniotic (one placenta, two amniotic sacs)
label: Twin gestation, monochorionic/diamniotic (one placenta, two amniotic sacs)
label_lc: twin gestation, monochorionic/diamniotic (one placenta, two amniotic sacs)