Maternal diet during pregnancy has been linked to offspring adiposity, but it is unclear whether maternal polyunsaturated fatty acid (PUFA) status during pregnancy affects offspring body composition.

We investigated the associations between maternal plasma n-3 and n-6 PUFA status at 34 wk gestation and offspring body composition.

A prospective United Kingdom population-based mother-offspring cohort, the Southampton Women's Survey (SWS), was studied.

A total of 12,583 nonpregnant women were recruited into the SWS, among whom 1987 delivered a baby before December 31, 2003; 293 mother-child pairs had complete measurements of maternal plasma PUFA concentrations in late pregnancy and offspring body composition at both ages 4 and 6 yr.

We measured offspring body composition by dual-energy x-ray absorptiometry, yielding fat mass, lean mass, percentage fat mass, and percentage lean mass. Results are presented as β-coefficients for standardized variables, therefore reflecting the sd change of the outcome for every 1 sd of the predictor.

After adjustment for maternal factors and child factors including height and duration of breast-feeding, maternal plasma n-6 PUFA concentration positively predicted offspring fat mass at 4 yr (β = 0.14 sd/sd;P = 0.01) and 6 yr (β = 0.11 sd/sd;P = 0.04), but there was no association with offspring lean mass at either age (β = 0.005 sd/sd,P = 0.89; and β = 0.008 sd/sd, P = 0.81, respectively). Maternal plasma n-3 PUFA concentration was not associated with offspring fat mass at 4 yr (β = 0.057 sd/sd;P = 0.34) or 6 yr (β = 0.069 sd/sd;P = 0.21). Maternal plasma n-3 PUFA status was positively associated with offspring lean mass on univariate analysis (4 yr, β = 0.11, P = 0.06; 6 yr, β = 0.14; P = 0.02); however, this was confounded by a positive association with offspring height.

This observational study suggests that maternal n-6 PUFA status during pregnancy might influence offspring adiposity in childhood.