Changes in activated protein C resistance during normal pregnancy

Byline: Mark C. Walker, Peter R. Garner, Erin J. Keely, Gail A. Rock, Marciano D. Reis Keywords: Activated protein C resistance; medical complications of pregnance; thrombophilia Abstract: OBJECTIVE: The objective of this study was to determine the changes in activated protein C resistance that occur during normal pregnancy. STUDY DESIGN: In this cross-sectional study activated protein C was measured in 128 women with normal pregnancies in the first, second, and third trimesters and in nonpregnant control subjects with 24 to 39 women in each group. In addition, factor V, factor VIII, free protein S, and functional protein C were measured and correlated with activated protein C levels. Polymerase chain reaction for factor V Leiden mutation was performed. RESULTS: There was a significant fall in the activity of activated protein C in the second and third trimesters of pregnancy (p < 0.05). This was related to increased factor VIII and decreased free protein S levels (p = 0.002, R.sup.2 = 0.20). The prevalence of the factor V Leiden mutation was 7.3%. CONCLUSION: Resistance to activated protein C is increased in the second and third trimesters of pregnancy. This is related to the alterations in other coagulation proteins, a phenomenon normally occurring during pregnancy. (Am J Obstet Gynecol 1997;177:162-9.) Author Affiliation: Ottawa, Ontario, Canada Article History: Received 18 November 1997; Revised 25 February 1997; Accepted 10 March 1997 Article Note: (footnote) [star] From the Department of Obstetrics and Gynecologya and the Department of Medicine,b University of Ottawa, and the Department of Pathology, University of Toronto.c , [star][star] Reprint requests: Peter R. Garner, MD, MSc, Department of Obstetrics and Gynecology, Civic Parkdale Cinic, Room 505, 737 Parkdale Ave., Ottawa, Ontario, Canada K1Y 1S8., a 6/1/81733