First-trimester uterine artery doppler in pregnancies with reactive hypoglycaemia or low 2-hour oral glucose tolerance test value: a retrospective study

BACKGROUND: Reactive hypoglycemia (RH) or low oral glucose tolerance test (OGTT) value has been linked with polyhydramnios and SGA, which is possibly due to placental dysfunction and glucose dysmetabolism. This study aims to investigate the perinatal outcomes associated with placental dysfunction and first-trimester uterine artery resistance in pregnancies with RH or a low 2-hour value on OGTT. METHODS: Pregnant women undergoing OGTT screening after 24 gestational weeks between 2021 and 2023 in maternity units in Indonesia were retrospectively evaluated. Women with multifetal pregnancy, pre-pregnancy diabetes, chronic hypertension, and fetal anomalies were excluded. GDM was diagnosed according to NICE criteria. RH was defined as a 2-hour OGTT value lower than or equivalent to the fasting value. First-trimester uterine artery pulsatility index (UtA-PI) and mean arterial pressure (MAP) were also recorded. Sensitivity analysis was performed using the other definitions of low OGTT values (2-hour OGTT value < 4 mmol/l and < 5 mmol/l). RESULTS: Of 343 pregnancies, 26 (7.58%) had RH whilst GDM was diagnosed in 70 (20.41%). Compared to women with normal glucose tolerance (NGT), women in the RH group were slimmer, had higher fasting glucose, and higher incidence of abnormal uterine artery resistance (left, right, sum, MoM), low birthweight (15.38% vs 4.05%), neonatal intensive care unit (NICU) admission (11.54% vs 3.24%), and preterm birth (11.54% vs 1.62%). The GDM cohort had higher fasting glucose than either RH or NGT; and a higher incidence of NICU admission (7.14% vs 3.24%) and preterm birth (8.57% vs 1.62%) than NGT, but not as high as women with RH. Abnormal uterine artery resistance and high incidence of adverse outcomes persist in the sensitivity analysis using definitions of 2-hour OGTT value < 4 mmol/l and < 5 mmol/l. CONCLUSIONS: RH may be another clinical presentation of glucose dysmetabolism in pregnancy, prone to adverse pregnancy outcomes, and an even higher frequency of low birthweight babies. The increased first-trimester uterine artery resistance in RH or low OGTT value implies the adverse outcomes may be placenta-driven.