The association of thrombophilia with fetal growth restriction.

Background: Thrombophilia or the tendency for thrombosis has been linked to pregnancy complications, which include fetal growth restriction. The aim of the present study was to determine the association of maternal thrombophilias with unexplained fetal growth restriction.

Methods: Inherited and acquired thrombophilias were checked in 34 women whose pregnancies were complicated by fetal growth restriction and 68 women with normal growth fetuses as controls, 8-10 weeks postpartum. Cases were matched for age, body mass index, and parity with two healthy women who had normal pregnancies during the same time period. Exclusion criteria were: maternal vascular disease, structural malformations, chromosomal abnormalities, cytomegalovirus infection, and history of drug abuse. Intrauterine growth restriction was diagnosed when the fetal weight or birth weight was below the 10th percentile for gestational age.

Results: The prevalence of all thrombophilia was 55.9% in the case group compared with 10.3% in the control group (P<0.001; OR: 11; 95% CI: 3.9 - 31.1). The prevalence of thrombophilic mutations were significantly higher in the case group compared with the control group (P=0.016; OR: 14.4; 95% CI: 1.7 - 124.8). The frequency of other types of inherited or acquired thrombophilias were significantly higher in fetal growth restriction cases than controls (P< 0.001; OR: 9.9; 95% CI: 3.2 - 30.9). Protein S deficiency was the most common thrombophilic defect in the fetal growth restriction group (41.1%) compared with 2.9% of controls (P<0.001). A significant difference in the frequency of multiple thrombophilias was noted between the two groups (P<0.001). All cases that had a history of fetal growth restriction during their previous pregnancies were positive for thrombophilic defects.

Conclusion: Fetal growth restriction pregnancies have a higher prevalence of thrombophilias.