Protein Z levels in pregnant Omani women: correlation with pregnancy outcome

Placental insufficiency resulting in fetal loss has been recognized in women with thrombophilic predisposition. Recent studies indicate that there is a high prevalence of protein Z (PZ) deficiency in patients with unexplained fetal loss. The objective of this study was to measure the PZ levels in pregnant Omani women in the first, second and third trimesters and correlate with the pregnancy outcome. The study enrolled 126 consecutive pregnant women after an informed consent prospectively. PZ was estimated in the first, second and third trimester in 15, 97 and 66 pregnant women respectively and they were followed for pregnancy outcomes including live birth, still birth, spontaneous abortion/induced abortion, maternal complications, fetal complications and health risks/complications in the newborn. The median PZ level (Mean ± SD) in the first, second and third trimester were 0.98 (1.07 ± 0.46), 1.3 (1.36 ± 0.61) and 1.44 (1.43 ± 0.69) (P < 0.05, Student's t-test, between first vs. second and first vs. third trimester). PZ deficiency defined as PZ level below 0.54 μg/ml (below 10th centile in the Omani population) was observed in 4 (4.7%) women, but interestingly all had a normal pregnancy outcome. Amongst the 43 subjects in whom paired PZ estimations were available, reducing PZ levels were observed from baseline values in 8 (33%) with normal pregnancy outcome; 5 (55%), with diabetes; 3 (50%) with hypertension and 2 (50%) with low birth weight respectively (P < 0.05, chi square test). PZ values increased progressively during the three trimesters of pregnancy. However, this increase is blunted in patients with abnormal pregnancy outcome like low birth weight babies or pregnancies associated hypertension or diabetes. Isolated PZ deficiency alone did not result in an abnormal outcome in this cohort of subjects.