Densities (number of fibres/mm2) of slow (□, male; ■, female) and fast (, male; , female) fibres (A) and oxidative (□, male; ■, female) and glycolytic (, male; , female) fibres (B) in gastrocnemius from 4-week-old rats. Pregnant rats were fed a control or low-protein (LP) diet at early (days 0–7 gestation, LPEarly), mid (days 8–14, LPMid), late (days 15–22, LPLate) or throughout gestation (days 0–22, LPAll). Values are log predicted means with the three error bars representing the standard errors of difference for comparing means on (a) different diets (between dams), (b) same diet different sex (between offspring) and (c) same diet same sex (between fibre types).