Inconsistent findings have been reported on associations between postnatal weight change with later blood pressure. This study analysed the impact of weight change during fetal life, infancy and later childhood on systolic blood pressure (SBP) in adolescence. A longitudinal population-based study was conducted in Stockholm, Sweden. Weight, length at birth and gestational age were extracted from the Medical Birth Register, weight and height in childhood was collected from child health records, and body size and SBP were measured during a health examination at 15 years of age. Complete data on 2438 individuals were analysed using linear regression. In fully adjusted models SBP increased 0.99 mmHg [95% confidence interval (CI), 0.27, 1.71] in girls and 1.02 mmHg [0.31, 1.73] in boys per 1 SD increase in weight during the first year of life. The effect on SBP of weight change from 10 to 15 years among boys was 3.70 mmHg [2.67, 4.73] and among girls 1.30 mmHg [0.38, 2.22] per 1 SD increase in weight. Weight gain in infancy and later childhood was positively associated with SBP at age 15 years, while birthweight showed a weaker inverse association with SBP. No apparent effect of weight gain from 1 to 10 years of age was seen. Degree of weight change in infancy was equally important for SBP in both boys and girls, while growth during puberty showed a stronger association with SBP among boys than among girls.