Second trimester amniotic fluid annexin A5 levels and subsequent development of intrauterine growth restriction

The purpose of this study was to investigate the levels of annexin A5 in second trimester amniotic fluid, and evaluate its correlation with subsequent development of intrauterine growth restriction (IUGR).

A total of 264 women undergoing mid-trimester amniocentesis between January 2007 and December 2007 were enrolled for the study. Amniocentesis was performed for routine indications. After delivery, outcome data were obtained.

Maternal age, frequency of nulliparity, fetal sex and gestational week at amniocentesis were similar between groups. As expected, prevalence of smoking was higher in IUGR developing mothers. Significant positive correlations were present between annexin A5 levels and gestational age at amniocentesis (P = 0.02) and maternal age (P = 0.01). Linear regression analysis revealed that annexin A5 levels were positively correlated with patient's age. Smoking women had significantly lower annexin A5 levels in the mid-trimester amniotic fluid (9.9 +/- 2.3 and 10.7 +/- 1.3 ng/mL, P = 0.01). Logistic regression analysis demonstrated that after controlling for gestational age at amniocentesis, smoking, maternal age, and maternal hypertension, annexin A5 was not significantly associated with IUGR (P = 0.07).

Amniotic fluid annexin A5 levels in the mid-trimester are not associated with IUGR at birth after controlling for maternal smoking and other confounders.