Objective: The purpose of this study was to determine the concentrations of serum insulin-like growth factor-I and insulin-like growth factor binding protein-1 in pregnancies that are complicated with primary antiphospholipid syndrome.
Study design: Longitudinal blood samples were collected from 8 weeks of gestation in 28 women with treated primary antiphospholipid syndrome and 19 control women. Serum insulin-like growth factor-I and insulin-like growth factor binding protein-1 were measured by immunoradiometric assay.
Results: Three antiphospholipid syndrome pregnancies miscarried, four pregnancies had intrauterine growth restriction and preeclampsia, six pregnancies had a thrombotic event, and one pregnancy had abruptio placentae. Mean (+/-SD) birth weight in antiphospholipid syndrome group was 2867 +/- 914 g (control, 3492 +/- 527 g; P =.02), and the mean gestation at delivery was 36.5 +/- 5.2 weeks (control, 40.3 +/- 0.7 weeks; P =.002). Insulin-like growth factor binding protein-1 and insulin-like growth factor-I concentrations increased with gestational age in both groups (2.8% and 2.4% per week), but insulin-like growth factor binding protein-1 was 61% higher in the antiphospholipid syndrome group (95% CI, 16%-122%; P =.004). Insulin-like growth factor-I was not significantly different (8% higher in antiphospholipid syndrome; 95% CI, -10% to 30%; P =.41).
Conclusion: Serum concentrations of insulin-like growth factor binding protein-1 are abnormal in the antiphospholipid syndrome group and may reflect abnormalities in trophoblast invasion.