Abstract:

Objective　To observe the maternal homocysteine（Hcy） concentrations during normal pregnancy， and to establish the reference interval of Hcy among women with normal pregnancy. Methods　A total of 942 normal pregnant women were enrolled. The relative data were collected， and they were followed up until delivery. The Hcy was detected during the first（98 pregnant women）， second（202 pregnant women）or third（642 pregnant women） trimesters of pregnancy by enzymatic cycling assay. Results　The serum Hcy concentrations among women with normal pregnancy were（7.25±2.90） μmol/L（95% reference interval 1.57-12.93 μmol/L）， including（6.87±2.78） μmol/L in the first trimester [the 75th percentile（P₇₅） 7.53 μmol/L]，（6.43±2.90） μmol/L in the second trimester（P₇₅ 7.21 μmol/L） and（7.54±2.86） μmol/L in the third trimester（P₇₅ 8.32 μmol/L）. There was statistical significance among the 3 groups（F＝12.03， P＝0.000）. There was statistical significance between the first trimester group with the second trimester group（t＝0.99， P＝0.321） and between the second trimester group with the third trimester group（t＝4.77， P＝0.000）. The Hcy concentration in the third trimester increased as（1.11±0.23） μmol/L for that in the second trimester [P＝0.000， 95% confidence interval（CI）（0.65-1.56） μmol/L]. Linearity correlation analysis showed that there was positive correlation of Hcy concentration with age and gestational weeks（r＝0.14 and 0.15， P＝0.000）. There was positive correlation of Hcy concentration in the third trimester with gestational weeks（r＝0.10，P＝0.009）. Multiple factor analysis showed that age， taking folic acid and gestational weeks were main factors for Hcy concentration（F＝16.59，P＝0.000）. Conclusions　The serum Hcy concentrations among women with normal pregnancy are 6.87 μmol/L in the first trimester， 6.43 μmol/L in the second trimester and 7.54 μmol/L in the third trimester. When the serum Hcy concentration ＞7.53 μmol/L in the first trimester（P₇₅），≥7.21 μmol/L in the second trimester（P₇₅） and 8.32 μmol/L in the third trimester（P₇₅）， the pregnant women may have hyperhomocysteinemia.

Key words: Homocysteine, Normal pregnant woman, Reference interval