First-trimester maternal serum alpha fetoprotein is associated with ischemic placental disease

Abstract

Background: While elevated second-trimester maternal serum alpha fetoprotein has been associated with adverse pregnancy outcomes, the utility of first-trimester maternal serum alpha fetoprotein in predicting these outcomes is limited. Some laboratories have been including maternal serum alpha fetoprotein as part of the first-trimester analyte screening for aneuploidy and preeclampsia, offering its potential utility in predicting pregnancy outcomes.

Objective: Our primary objective was to determine the association between elevated first-trimester maternal serum alpha fetoprotein and preeclampsia as well as ischemic placental disease (a composite of preeclampsia, fetal growth restriction, and/or placental abruption). Secondary outcomes included early-onset preeclampsia requiring delivery at <34 weeks gestation, fetal growth restriction, placental abruption, preterm delivery, fetal demise, and spontaneous abortion.

Study design: An institutional review board-approved multisite retrospective cohort study was performed including all patients with first-trimester maternal serum alpha fetoprotein as part of routine first-trimester aneuploidy screening from April 2015 through January 2017. Pregnancies with multiple gestations, known structural or chromosomal abnormalities, known malignancy, and incomplete delivery records were excluded. Delivery records were reviewed for baseline characteristics and adverse pregnancy outcomes. The optimal cutoff point for first-trimester maternal serum alpha fetoprotein to predict these outcomes was assessed, and an elevated maternal serum alpha fetoprotein was considered >2.0 multiple of the median. A Fisher exact test and odds ratios were used to determine the association between elevated first-trimester maternal serum alpha fetoprotein and adverse pregnancy outcomes. Spearman correlation coefficient assessed the relationship between first- and second-trimester maternal serum alpha fetoprotein.

Results: Of 1478 patients with first-trimester maternal serum alpha fetoprotein, 1280 had complete records available for review (86.6%). There was no association demonstrated between elevated first-trimester maternal serum alpha fetoprotein (>2.0 multiple of the median) and the primary outcome, overall preeclampsia (5.8% vs 4.6%, odds ratio, 1.29, 95% confidence interval, 0.58-2.91). However, there was an increased incidence of ischemic placental disease, 15.8% vs 7.7% (odds ratio, 2.26, 95% confidence interval, 1.33-3.87) in those with an elevated alpha fetoprotein. Also, elevated first-trimester maternal serum alpha fetoprotein was associated with a higher incidence of fetal growth restriction (7.5% vs 2.3%, odds ratio, 3.40, 95% confidence interval, 1.56-7.42) and preterm birth (18.3% vs 10.3%, odds ratio, 1.95, 95% confidence interval, 1.18-3.21). Also, a positive correlation between first- and second-trimester maternal serum alpha fetoprotein was demonstrated (rho = 0.46, P < .0001).

Conclusion: Elevated first-trimester maternal serum alpha fetoprotein is associated with ischemic placental disease, fetal growth restriction, and preterm birth. This suggests that elevated maternal serum alpha fetoprotein may help to identify high risk pregnancies as early as the first trimester of pregnancy. Future studies are necessary to determine whether the addition of first-trimester maternal serum alpha fetoprotein to existing algorithms can improve the early detection of ischemic placental disease.

Keywords: first trimester; ischemic placental disease; maternal serum alpha fetoprotein; preeclampsia.