First Trimester Combined Test (FTCT) as a Predictor of Gestational Diabetes Mellitus

Abstract

Background-The first trimester combined test (FTCT) is an effective screening tool to estimate the risk of fetal aneuploidy. It is obtained by the combination of maternal age, ultrasound fetal nuchal translucency (NT) measurement, and the maternal serum markers free β-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein A (PAPP-A). However, conflicting data have been reported about the association of FTCT, β-hCG, or PAPP-A with the subsequent diagnosis of gestational diabetes mellitus (GDM). Research design and methods-2410 consecutive singleton pregnant women were retrospectively enrolled in Calabria, Southern Italy. All participants underwent examinations for FTCT at 11-13 weeks (plus 6 days) of gestation, and screening for GDM at 16-18 and/or 24-28 weeks of gestation, in accordance with current Italian guidelines and the International Association Diabetes Pregnancy Study Groups (IADPSG) glycemic cut-offs. Data were examined by univariate and logistic regression analyses. Results-1814 (75.3%) pregnant women were normal glucose tolerant, while 596 (24.7%) were diagnosed with GDM. Spearman univariate analysis demonstrated a correlation between FTCT values and subsequent GDM diagnosis (ρ = 0.048, p = 0.018). The logistic regression analysis showed that women with a FTCT <1:10000 had a major GDM risk (p = 0.016), similar to women with a PAPP-A <1 multiple of the expected normal median (MoM, p = 0.014). Conversely, women with β-hCG ≥2.0 MoM had a reduced risk of GDM (p = 0.014). Conclusions-Our findings indicate that GDM susceptibility increases with fetal aneuploidy risk, and that FTCT and its related maternal serum parameters can be used as early predictors of GDM.

Keywords: fetal nuchal translucency; first trimester combined test; gestational diabetes mellitus; pregnancy-associated plasma protein A (PAPP-A); β-human chorionic gonadotropin.

Figure 1

Flow chart indicating the selection of the study population. OGTT: oral glucose tolerance test; GDM: gestational diabetes mellitus; FTCT: first trimester combined test.

Figure 2

Receiver-operating-characteristic (ROC) curves of FTCT parameters for the prediction of GDM. β-hCG: β-human chorionic gonadotropin; PAPP-A: pregnancy-associated plasma protein A; NT: nuchal translucency.