Stress reactivity is a disposition that underlies individual differences in stress responses, thereby affecting vulnerability for the development of disease. Besides genetic and early postnatal environmental factors, stress reactivity has been shown to be influenced by an adverse prenatal developmental environment, but it is unclear if such effects persist into older age. We tested associations between fetal growth and perceived stress reactivity in 421 participants from the Hertfordshire Cohort at age 66–75 years. Regression analysis showed a U-shaped association between birth weight and perceived stress reactivity with increased levels of stress reactivity at the lower and upper end of the birth weight distribution. These effects were stable after adjustment for markers of early adversity and recent adversity and chronic stress. Although the effects were small, they are consistent with findings from studies in younger cohorts, and demonstrate that such effects can persist into older age. Copyright © 2012 John Wiley & Sons, Ltd.