Plasma MIC-1 and PAPP-A Levels Are Decreased among Women Presenting to an Early Pregnancy Assessment Unit, Have Fetal Viability Confirmed but Later Miscarry

Abstract

Background: We have recently shown first trimester Macrophage inhibitory cytokine-1 (MIC-1) and Pregnancy Associated Plasma Protein-A (PAPP-A) serum concentrations are depressed among asymptomatic women destined to miscarry. Here we examined whether plasma levels of MIC-1 and PAPP-A are depressed among women presenting to an Early Pregnancy Assessment Unit (EPAU), noted to have a confirmed viable fetus, but subsequently miscarry. Methods: We performed a prospective cohort study, recruiting 462 women in the first trimester presenting to EPAU and had fetal viability confirmed by ultrasound. We obtained plasma samples on the same day and measured MIC-1, PAPP-A and human chorionic gonadotrophin (hCG), grouping the cohort according to whether they later miscarried or not. To correct for changes in analyte levels across gestation, we expressed the data as Multiples of the normal Median (MoMs). Results: We recruited 462 participants presenting to EPAU at 5-12 weeks gestation. Most (80%) presented with symptoms of threatened miscarriage (e.g. abdominal pain, vaginal bleeding). 34 (7.4%) subsequently miscarried. Median plasma MIC-1 levels among those who miscarried were 50% of those with ongoing pregnancies (Miscarriage cohort MoM 0.50 (25th-75th centiles: 0.29-1.33) vs ongoing pregnancies MoM 1.00 (0.65-1.38); p=0.0025). Median plasma PAPP-A MoMs among those who miscarried was 0.57 (0.00-1.12), significantly lower than those with ongoing pregnancies (MoMs 1.00 (0.59-1.59); p=0.036). Plasma hCG levels were also significantly depressed among those who miscarried compared to those with ongoing pregnancies. However, the performance of MIC-1 as a diagnostic marker to predict miscarriage in this cohort was modest, and not improved with the addition of hCG. Conclusion: MIC-1 and PAPP-A levels are significantly depressed in women presenting to EPAU with ultrasound evidence of fetal viability, but later miscarry. While they are unlikely to be useful as predictive biomarkers in this clinical setting, they probably play important roles in the maintenance of early pregnancy.