Study objective: To relate measures of fetal growth/size other than birth weight with subsequent blood pressure measured on the same individuals within the context of the “fetal origins of adult disease”. Design: A prospective cohort study in which measurements of fetal dimensions obtained by serial ultrasound imaging between 18 and 38 weeks gestation were analysed with reference to systolic blood pressure measurements on the offspring at age 6 years. Setting: Perth, Western Australia. Participants: A subgroup of 707 eligible mother-fetus pairs from a cohort of 2876 pregnant women and their offspring. The number of mother-fetus pairs varied at each gestational age and by measurement of fetal dimension. Subsequent blood pressure recordings were obtained on approximately 300 of the offspring at age 6 years. Main results: The findings confirmed the inverse association between birth weight and systolic blood pressure at age 6. There was, also, an inverse relation between fetal femur length and systolic blood pressure at age 6, adjusted for current height. Furthermore, an inverse association was demonstrated between a statistically derived measure of fetal growth (conditional z score) between 18 and 38 weeks gestation and later systolic blood pressure at age 6. The effect sizes for all three relations were in the order of 1–2 mm Hg per standard deviation change. Conclusion: The mechanisms underpinning the “fetal origins” hypothesis may be operative early in pregnancy and may be reflected in the length of the fetal femur in early to mid-pregnancy.