The relationship between amniotic fluid alpha-fetoprotein, alkaline phosphatase and ferritin in the second trimester of pregnancy and preterm birth

Preterm birth is one of the most important complications of pregnancy, which has a significant impact on the health and mortality of neonates, so early diagnosis and prediction is vital. This study was performed with aim to investigate the relationship between amniotic fluid alpha-fetoprotein (αFP), alkaline phosphatase (ALP) and ferritin in the second trimester of pregnancy and preterm birth. 
This cross-sectional analytical study was performed on 60 subjects with gestational age of 15-20 weeks (mean of 17 weeks) who had performed amniocentesis due to positive first-trimester screening from September 2014 to February 2015. The levels of αFP, ALP and ferritin were tested using spectrophotometric and ELISA method in freeze samples of 40 subjects with term birth and 20 subjects with preterm birth. Data were analyzed by SPSS software (version 22) and t-test and Chi-square test. P<0.05 was considered statistically significant.
The mean amniotic fluid αFP in term and preterm birth was 382.14 ± 96.44 and 547.47 ± 122.83(ng/ml), respectively; the mean ALP in term and preterm birth was 27.35 ± 13.01 and 74.45±15.51 (IU/ L), respectively; and the mean ferritin was 382.14 ± 96.44, and 547.47±122.83 (ng/ml), respectively. The level of all three markers was significantly higher in preterm birth than term birth (p < 0.001).
There is significant and positive relationship between amniotic fluid αFP, ALP and ferritin levels with preterm birth that may help to increase our understanding of the pathophysiology of preterm birth. According to the results, it is recommended to perform further research with larger sample sizes.