Role of Maternal Serum Human Placental Lactogen in First Trimester Screening

The most preferred antenatal screening test is first trimester dual test which has a detection rate of 95% for foetal chromosomal anomaly. Maternal serum free β human chorionic gonadotropin (free β hCG) and pregnancy associated plasma protein A are used in first trimester dual test along with maternal demographic and foetal sonographic indices to calculate risk for foetal aneuploidy. Human placental lactogen is a placental hormone that is present in maternal serum only during pregnancy and its level rises in relation to the growth of the foetus and placenta. The objectives of this study was to measure and correlate maternal serum hPL with free β hCG, maternal age, maternal age related risk ratio and calculated risk ratio of first trimester screening. After obtaining permission from the Institutional Ethics Committee, hPL and free β hCG were measured from the serum of 84 pregnant women aged 20-40 years in 11-13th weeks + 6 days of gestation who underwent dual test during their antenatal check-up. Independent t test, Pearson's correlation, Spearman's correlation, Mann-Whitney U test, ANOVA were used wherever appropriate. A significant positive correlation between maternal serum hPL, maternal age related aneuploidy risk ratio (p value < 0.001) and aneuploidy risk ratio at the time of delivery (p value < 0.001) was observed. Also maternal age was negatively correlated with maternal serum hPL (p value < 0.001) and positively correlated with maternal serum free β hCG (p value 0.023). A significant negative correlation between maternal serum hPL and free β hCG (p value < 0.001) was found. To conclude low level of maternal serum hPL in advanced maternal age may reflect decreased functional syncytiotrophoblast mass which may predispose to adverse pregnancy outcome. As chance of baby born with chromosomal anomaly is known to increase with advancing maternal age, hPL may have role in first trimester screening.