First-Trimester Parameters and Mid-Second-Trimester Uterine Doppler Indices

INTRODUCTION: Objective: To evaluate the association linking initial combined screening parameters to middle second-trimester uterine artery Doppler markers in a nulliparous population.
METHODS: A total of 227 nulliparous pregnancies with complete initial screening profiles and mid-second-trimester uterine artery Doppler metrics (18–24 gestational weeks) were evaluated in this retrospective cohort framework. Serum free β-hCG, PAPP-A, and nuchal translucency (NT) metrics from the first trimester were formulated as multiples of the median (MoM). The average uterine artery pulsatility index (mean UtA-PI) was derived, with values at or above the 90th percentile (1.545) designating elevated resistance. Analytical steps involved correlation coefficients, multivariable logistic regression, and ROC curve tracking.
RESULTS: A significant inverse link was found between PAPP-A MoM and mean UtA-PI (r = −0.34, p < 0.001). multivariable logistic regression, identified decreased PAPP-A MoM as an independent predictor for elevated uterine artery resistance (OR = 2.61; 95% CI: 1.46–4.67; p = 0.001), whereas NT MoM and free β-hCG showed no notable associations. PAPP-A displayed moderate accuracy in predictive ROC assessments (AUC = 0.72), yielding an ideal cut-off threshold of 0.65 MoM (sensitivity: 69.6%, specificity: 70.3%). Furthermore, mean UtA-PI levels were substantially elevated in subjects exhibiting PAPP-A values below 0.65 MoM..
DISCUSSION AND CONCLUSION: Elevated uterine artery resistance during the mid-second trimester is linked to diminished initial PAPP-A concentrations in nulliparous individuals. Such data imply that early biochemical fluctuations could mirror a disrupted uteroplacental vascular remodeling process. Future prospective trials incorporating clinical pregnancy outcomes remain essential.

Keywords: PAPP-A, uterine artery Doppler, pulsatility index, nulliparous pregnancy, placentation