Background The present study aimed to investigate the association between gestational weight gain (GWG) and birth weight, as well as the body mass index (BMI) status, of children at the ages of 2 and 8 years.

Methods Population‐based data were obtained from a database of all 7–9‐year‐old Greek children who attended primary school during 1997–2007. The study sample consisted of 5125 children matched with their mothers, randomly selected according to region and place of residence, and equally distributed (approximately 500 per year) throughout the study period (1997–2007). A standardised questionnaire was applied; telephone interviews were carried out to collect maternal age, BMI status at the beginning and the end of pregnancy and GWG, birth weight of offspring and BMI status at the ages of 2 and 8 years, as well as several other pregnancy characteristics (e.g. pregnancy duration, gestational medical problems, maternal smoking and alcohol consumption habits, and lactation of offspring after pregnancy).

Results Gestational weight gain was positively associated with the weight status of offspring at all three life stages studied: newborn (birth weight), infant (BMI) and child (BMI) [b = 0.008 (0.001), b = 0.053 (0.009) and b = 0.034 (0.007), respectively, all P < 0.001], after adjusting for maternal age at pregnancy (significant inverse predictor only at age 2 years). The same applied to excessive GWG, as defined by the Institute of Medicine guidelines.