Abnormal First Trimester Maternal Serum Biochemical Markers and Prediction of Adverse Pregnancy Outcomes

Abstract

Objective: To review the obstetric outcomes associated with abnormal first trimester maternal serum markers, including pregnancy-associated plasma protein A and beta-human chorionic gonadotrophin.
Methods: A retrospective review of all singleton pregnancies with first trimester Down syndrome screening by a combination of fetal nuchal translucency thickness, and maternal serum pregnancy-associated plasma protein A and beta-human chorionic gonadotropin done at 11+0 to 13+6 weeks of gestation in a public hospital from 1 July 2010 to 31 December 2011 was conducted. The biochemical markers were converted to multiples of the expected normal median for a pregnancy of the same gestation. The associations between abnormal biochemical markers and adverse pregnancy outcomes, including small for gestational age, preterm delivery, low Apgar score, neonatal intensive care unit admission rate, miscarriage, and stillbirth were studied.
Results: A total of 4367 women were included in the study. Low pregnancy-associated plasma protein A level (<0.4 multiples of the expected normal median) was significantly associated with an increased rate (adjusted odds ratios) of small-for-gestational-age infants (4.8; 95% confidence interval, 2.8-8.2), preterm deliveries (2.0; 1.3-3.2), neonatal intensive care unit admissions (3.1; 1.8-5.3), and stillbirths (7.7; 2.0-29.1), but not low Apgar scores (2.6; 0.8-8.6) or miscarriages (1.3; 0.7-2.6). A low beta-human chorionic gonadotrophin level (<0.4 multiples of the expected normal median) was not associated with any of these adverse outcomes, except in a subgroup analysis of low Apgar score in gestation at or after 37 weeks.
Conclusion: Low pregnancy-associated plasma protein A level was significantly associated with increased rates of small-for-gestational-age infants, preterm deliveries, neonatal intensive care unit admissions, and stillbirths. These results may help in counselling women and consideration of increased fetal surveillance in such cases.