Association between polyhydramnios and decreased fetal movements: A retrospective cohort study

OBJECTIVE: To evaluate the association between polyhydramnios and maternal perception of decreased fetal movements (DFM) and to explore whether a volume-dependent threshold exists for this effect. METHODS: This retrospective cohort study included 7215 singleton pregnancies (2006-2025). The exposed group comprised 2066 women with polyhydramnios (amniotic fluid index AFI >25 cm or maximal vertical pocket >8 cm), and the unexposed group included 5149 women with normal amniotic fluid volume. DFM rates were compared across gestational age groups and polyhydramnios severity. Adjusted odds ratios (aOR) were estimated using multivariable logistic regression. RESULTS: The overall rate of DFM did not differ significantly between the polyhydramnios and comparison groups (7.5% versus 7.9%; P = 0.55; aOR 0.99, 95% confidence interval 0.81-1.22). In exploratory subgroup analyses, women with moderate-to-severe polyhydramnios (AFI ≥30 cm) reported DFM more frequently than those with mild polyhydramnios (13.7% versus 7.2%; P = 0.014). DFM was also more frequently reported in the polyhydramnios group before term (early third trimester 0.8% versus 0.3%, P = 0.006; late preterm 4.5% versus 1.9%, P < 0.001), whereas this pattern reversed at term. Polyhydramnios was associated with higher rates of cesarean delivery (36.4% versus 27.5%), neonatal hypoglycemia (4.3% versus 2.1%), and neonatal intensive care unit admission (8.3% versus 6.7%; all P < 0.001). CONCLUSION: Overall DFM rates were similar between groups. In exploratory, hypothesis-generating analyses, high amniotic fluid volumes (AFI ≥30 cm) were associated with more frequently reported DFM, possibly reflecting altered maternal perception. Reports of DFM in moderate-to-severe polyhydramnios may warrant increased vigilance and objective assessment.