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Medline ® Abstract for Reference 56

of 'Maternal adaptations to pregnancy: Hematologic changes'

Development of resistance to activated protein C during pregnancy.
Cumming AM, Tait RC, Fildes S, Yoong A, Keeney S, Hay CR
Br J Haematol. 1995;90(3):725.
We measured activated protein C (APC) anticoagulant activity in 20 healthy women at 14-20, 28 and 36 weeks gestation, and at 1 d post-partum. Significant reductions in the mean APC sensitivity ratio (APC-SR) were observed at all stages of pregnancy studied compared with the mean APC-SR obtained for baseline measurements carried out at>8 weeks post-partum. APC resistance was seen in 8/19 (42%) and in 11/20 (55%) women at 14-20 and 28 weeks gestation respectively. The development of resistance to APC may contribute to the increased risk of thrombosis during pregnancy.
University Department of Haematology, Manchester Royal Infirmary.