Human placental lactogen is a first-trimester maternal serum marker of Down syndrome

BACKGROUND: Human placental lactogen (hPL) is synthesised by the placenta and found in maternal serum. We analysed the potential of hPL as a first-trimester maternal serum-screening marker for fetal Down syndrome (DS). MATERIALS AND METHODS: hPL was quantified by ELISA in 47 DS pregnancies and 136 controls in gestational weeks 8-13. Distributions of log multiples of the median (MoMs) were established. The quantity of hPL in DS screening was estimated using Monte Carlo simulation methods. RESULTS: The mean log10 MoM hPL was - 0.1995 (SD: 0.1993) in affected and 0.0026 (SD: 0.2129) in control pregnancies. This corresponds to a MoM of 0.63 in DS pregnancies. hPL correlated significantly with log10 MoM values of hCGbeta (r = 0.320) and PAPP-A (r = 0.590) in controls, but not with hCGbeta (r = 0.228) or PAPP-A (r = 0.090) in DS pregnancies. The inclusion of hPL in the double test (PAPP-A + hCGbeta) increased the detection rate from 67 to 75% for a false-positive rate of 5%. CONCLUSION: hPL is a DS screening marker that is applicable at weeks 9-13 and could be included in multiple marker first-trimester screening for DS.