Objective: To prospectively analyze the predictive value of fasting plasma glucose (FPG) before and during early pregnancy for gestational diabetes mellitus (GDM) and adverse pregnancy outcomes.

Methods: 565 women who underwent pre-pregnancy exams and became pregnant within six months at Chongqing Maternal and Child Health Hospital (Jan 2020–Jan 2021) were enrolled. Preconception FPG was measured and divided into low (3.9–5.0 mmol/L) and high (5.0–6.1 mmol/L) groups. Early pregnancy FPG (10–12 weeks) was divided into low (3.9–4.5 mmol/L) and high (4.5–5.1 mmol/L) groups. OGTT at 24–28 weeks classified GDM status. Risk factors, FPG thresholds, and adverse outcomes were analyzed.

Results: Pre-pregnancy BMI ≥24.00 kg/m², preconception FPG ≥4.95 mmol/L, and family diabetes history were GDM risk factors. High preconception FPG correlated with higher early pregnancy FPG (P<0.05). FPG ≥4.95 mmol/L before pregnancy significantly increased GDM risk. FPG ≥5.0 mmol/L before pregnancy or >4.5 mmol/L in early pregnancy increased adverse outcomes (spontaneous abortion, stillbirth, preterm delivery, macrosomia, low birth weight) (P<0.05).

Conclusions: Clinical attention is warranted when preconception FPG ≥4.95 mmol/L or early pregnancy FPG >4.5 mmol/L. Timely intervention may help prevent GDM and reduce maternal‑perinatal risks.

Wei Wang is an attending physician in the Department of Gynecological Endocrinology at Chongqing Health Center for Women and Children. She holds a Master's degree from Hebei Medical University (seven-year program). She specializes in adolescent development assessment, preconception care, postpartum care, early pregnancy and recurrent miscarriage, reproductive tract infections, polycystic ovary syndrome (PCOS), and menstrual disorders.