Background: Emerging evidence suggests an association of maternal PUFA concentrations during pregnancy with child cognitive and neuropsychiatric outcomes such as intelligence and autistic traits. However, little is known about prenatal maternal PUFAs in relation to child brain development, which may underlie these associations. Objectives: We aimed to investigate the association of maternal PUFA status during pregnancy with child brain morphology, including volumetric and white matter microstructure measures. Methods: This study was embedded in a prospective population-based study. In total, 1553 mother-child dyads of Dutch origin were included. Maternal plasma glycerophospholipid PUFAs were assessed in midpregnancy. Child brain morphologic outcomes, including total gray and white matter volumes, as well as white matter microstructure quantified by global fractional anisotropy and mean diffusivity, were measured using MRI (including diffusion tensor imaging) at age 9-11 y. Results: Maternal ω-3 (n-3) long-chain PUFA (LC-PUFA) concentrations during pregnancy had an inverted U-shaped relation with child total gray volume (linear term: β: 16.7; 95% CI: 2.0, 31.5; quadratic term: β: -1.1; 95% CI: -2.1, -0.07) and total white matter volume (linear term: β: 15.7; 95% CI: 3.6, 27.8; quadratic term: β: -1.0; 95% CI: -1.8, -0.16). Maternal gestational ω-6 LC-PUFA concentrations did not predict brain volumetric differences in children, albeit the linolenic acid concentration was inversely associated with child total white matter volume. Maternal PUFA status during pregnancy was not related to child white matter microstructure. Conclusions: Sufficient maternal ω-3 PUFAs during pregnancy may be related to more optimal child brain development in the long term. In particular, exposure to lower ω-3 PUFA concentrations in fetal life was associated with less brain volume in childhood. Maternal ω-6 LC-PUFAs were not related to child brain morphology.