First trimester maternal serum biochemical markers of aneuploidy in pregnancies with abnormally invasive placentation.

OBJECTIVE

To examine whether differences exist in routine first trimester maternal serum screening analyte measurements between normal pregnancies, placenta praevia and abnormally invasive placentation (AIP).

DESIGN

Multidisciplinary audit.

SETTING

Associated university teaching hospital with 9000 annual deliveries.

POPULATION: Five hundred and sixteen pregnancies in total, including 344 normal controls, 17 with AIP and 155 placenta praevia cases.

METHODS

Comparison of maternal serum free βhCG and PAPP-A MoMs distribution in pregnancies with abnormally invasive placentation, placenta praevia and normal controls, after correcting for known confounding factors between October 2005 and September 2013. Data from a previously published first trimester AIP and biochemistry study were combined with our study data and compared in the above way to complete the analysis.

MAIN OUTCOME MEASURES: Differences in first trimester maternal serum PAPP-A and free βhCG in AIP, placenta praevia, and normal pregnancies.

RESULTS

Median free βhCG MoM in the control group was 1.04, and 1.08 (P = 0.859) in the placenta praevia group compared with 0.81 in the AIP group (P = 0.06). Median PAPP-A MoM was 1.01 in the control group and 1.05 (P = 0.83) in praevia, compared with 1.22 in AIP cases (0.16). The combined AIP dataset gave an overall PAPP-A median MoM of 1.40, and free βhCG of 0.85. Both markers showed a significantly different distribution from controls (PAPP-A P = 0.002 and free βhCG P = 0.031).

CONCLUSIONS

There may be differences between first trimester maternal serum biochemical markers between normal pregnancies and those complicated by abnormally invasive placentation. If upheld, this may provide useful information for the early identification of abnormally invasive placentation. More studies are required.