Background/Objectives: Pregnancies complicated by idiopathic polyhydramnios are linked to a heightened risk of numerous maternal and perinatal complications. We aim to study the implications of polyhydramnios in term pregnancies complicated with gestational diabetes mellitus (GDM). Methods: A prospective cohort study including 340 GDM cases was conducted. An ultrasound scan was conducted at term between 37 and 40 weeks and amniotic fluid volume (AFV) was assessed by measuring the amniotic fluid index (AFI) and the single deepest pocket (SDP). Maternal demographics and obstetric and perinatal outcomes were evaluated after delivery. We performed comparisons between groups with normal AFV and polyhydramnios (AFI ≥ 24 cm or SDP ≥ 8 cm), and between groups with normal and increased AFV (AFI or SDP ≥ 75th centile). A multivariate logistic regression analysis was performed to study association between AVF measurements and adverse maternal and perinatal outcomes. Results: We found that women with GDM and polyhydramnios at term had a higher risk of maternal (54.3 vs. 27.5%, p < 0.001) and perinatal adverse outcomes (65.7% vs. 46.5%, p < 0.03). The increased AFV group showed a higher risk of fetal overgrowth (LGA: 21.4% vs. 8.2%, p < 0.001 and macrosomia: 19.8% vs. 5.4%, p < 0.001, respectively) and a lesser risk of delivering an SGA fetus (6.3% vs. 13.6%, respectively). Both AFI and SDP showed a significant correlation with newborn weight (r = 0.27; p < 0.001 and r = 0.28; p < 0.001, respectively) and newborn centile (r = 0.26; p < 0.001 and r = 0.26 for both). Subsequent to conducting a multivariate logistic regression analysis adjusted for pregestational BMI, nulliparity, and insulin treatment, both AFI and SDP were significantly associated with perinatal complications, but AFI showed a stronger association with fetal overgrowth (aOR 1.11; p = 0.004 for a LGA fetus and aOR 1.12; p = 0.002 for macrosomia) and with lower risk of delivering an SGA fetus (aOR 0.89; p = 0.009) or IUGR fetus (aOR 0.86; p = 0.03). ROC analysis showed a poor diagnostic performance of both AFI and SDP for identifying macrosomia (AUC 0.68 for AFI, and 0.65 for SDP). Conclusions: Detection of polyhydramnios at term, whether using AFI or SDP, identifies a subgroup of women with gestational diabetes with higher risks of obstetric and perinatal complications. Cases with increased AFV (AFI ≥ 18 cm or SDP ≥ 6.5 cm) are also associated with an increased risk of fetal overgrowth and may require more intensive monitoring for management and optimal delivery timing, with the aim of improve perinatal outcomes.

Background/Objectives: Fetal growth disorders and hypertensive disorders of pregnancy share pathophysiological pathways rooted in impaired first-trimester placentation. We asked whether three-dimensional placental volume and the VOCAL vascular indices add prognostic information to first-trimester screening and how repeatable and setting-dependent they are. Methods: A prospective cohort of 445 singleton pregnancies was scanned at 11+0–13+6 weeks, twice each at two pulse repetition frequencies (2.3 and 0.9 kHz). Markers were converted to crown–rump-length-adjusted z-scores. The primary analysis tested the incremental value of volume over clinical risk factors plus PAPP-A for a composite of hypertensive disorders, fetal growth restriction or small-for-gestational-age birth, with bootstrap optimism correction (1000 resamples). Results: The composite outcome occurred in 69/407 women (17.0%). Volume was repeatable (intraclass correlation 0.90) and not measurably associated with maternal adiposity, whereas the indices differed threefold between paired acquisitions obtained at different settings, varied between operators and fell with body mass index. Volume was associated with the outcome independently of clinical risk factors and PAPP-A (likelihood-ratio p < 0.001; odds ratio 0.55 per SD, 95% CI 0.41–0.74) and of the combined preeclampsia-screening components; the corresponding increase in the area under the curve was small (optimism-corrected 0.59 to 0.66) and not significant by DeLong’s test (p = 0.13), and calibration slopes indicated overfitting. The indices showed no consistent incremental value. Small placentas preceded growth restriction (composite outcome 45% below the study-derived 5th centile), and large placentas preceded large-for-gestational-age birth. With four cases of preeclampsia, the study is uninformative for preeclampsia-specific prediction. Conclusions: First-trimester placental volume is a reproducible marker, not measurably associated with maternal adiposity, which was independently associated with fetal growth disorders in this cohort; the resulting gain in discrimination was small and its clinical value is unproven. Aspirin use after screening was not recorded. External validation, assessment of reproducibility between operators and analysts, and evaluation of clinical utility are required before any use in practice. The vascular indices are acquisition- and habitus-dependent and showed no consistent incremental prognostic value.