Plasma progesterone, estradiol, and unconjugated estriol concentrations in twin pregnancies: relation with cervical length and preterm delivery

- Johnsson, Vilma L.; Pedersen, Nina G.; Rode, Line; Worda, Katharina; Krampl-Bettelheim, Elisabeth; Skibsted, Lillian; Hinterberger, Stefan; Strobl, Isolde; Bowman, Maria E.; Smith, Roger; Tabor, Ann