Placental weight measured at birth was available for 17 of 46 bichorial twin pregnancies (mean, 964 g; median, 985 g; range, 600-1270 g) and for 5 of 7 monochorial twin pregnancies (mean, 953 g; median, 735; range, 600-1530 g).
A linear regression model was then fitted to evaluate the difference between MM pregnancies, distinguished as monochorial and bichorial, and MF ones, correcting for effect of week of gestation (Table 1).