BACKGROUND: Human evidence on the effects of early life phthalate exposure on obesity and cardiovascular disease risks, reported by experimental studies, is limited to a few cross-sectional studies. OBJECTIVES: We evaluated the associations between prenatal phthalate exposure and childhood growth and blood pressure in a Spanish birth cohort study. METHODS: We assessed exposure using the average of two phthalate metabolite spot-urine concentrations collected from the mothers in the first and third pregnancy trimesters (creatinine-adjusted, n = 391). Study outcomes were the difference in age- and sex-specific z-scores for weight between birth and 6 months of age; and repeated age- and sex-specific z-scores for body mass index (BMI) at 1, 4, and 7 years; waist-to-height ratio at 4 and 7 years; and age- and height-specific z-scores for systolic and diastolic blood pressure at 4 and 7 years. RESULTS: The sum of five high-molecular-weight phthalate metabolites (ΣHMWPm) was associated with lower weight z-score difference between birth and 6 months (β per doubling of exposure = -0.41; 95% CI: -0.75, -0.06) and BMI z-scores at later ages in boys (β = -0.28; 95% CI: -0.60, 0.03) and with higher weight z-score difference (β = 0.24; 95% CI: -0.16, 0.65) and BMI z-scores in girls (β = 0.30; 95% CI: -0.04, 0.64) (p for sex interaction = 0.01 and 0.05, respectively). The sum of three low-molecular-weight phthalates (ΣLMWPm) was not significantly associated with any of the growth outcomes. ΣHMWPm and ΣLMWPm were associated with lower systolic blood pressure z-scores in girls but not in boys. CONCLUSIONS: This study suggests that prenatal phthalate exposure may be associated with postnatal growth and blood pressure in a sex-specific manner. Inconsistencies with previous cross-sectional findings highlight the necessity for evaluating phthalate health effects in prospective studies. ; This study was funded by grants from the RecerCaixa (Register no. 2010ACUP00349), the “Instituto Carlos III” (Red INMA G03/176, CB06/02/0041 and ...