Condie R, Campbell D
Br J Obstet Gynaecol. 1978 Jan;85(1):37-9. doi: 10.1111/j.1471-0528.1978.tb15822.x.
Components of the haemostatic mechanism were measured at intervals throughout pregnancy in 11 patients with twins and compared with a group of 21 patients with singleton pregnancies. Mean plasma fibrinogen levels were consistently (but not significantly) elevated in the mothers of twins while other parameters showed no differences.