Background: Gestational weight gain (GWG) is known to be a potential risk factor for short-term postpartum weight retention (PPWR) and thus for overweight in women. Does GWG also determine the long-term risk of overweight in women? Objective: We aimed to study the short-and long-term effects of GWG in accordance with the Institute of Medicine (IOM) recommendations on postpartum weight retention. Design: We systematically reviewed 5 databases and bibliographies of various publications supplemented by hand search for relevant articles published in English or German and performed meta-analyses to quantify the effect estimate of PPWR by using a random-effects model. We split the data into 4 categories of follow-up: ,0.5, 0.5-1, ;3, and 15 y. Results: Of 1770 search hits, 9 observational studies remained suitable for the analysis. PPWR increased after longer time spans after delivery irrespective of whether GWG had been below, within, or above the guidelines. Compared with women with GWG within the recommendations, those with a GWG above the recommendations retained an additional 3.06 kg (95% CI: 1.50, 4.63 kg) after 3 y and 4.72 kg (95% CI: 2.94, 6.50 kg) on average after 15 y postpartum. Inadequate GWG was associated with less PPWR (22.99 kg; 95% CI: 23.72, 22.27 kg) ,6 mo after pregnancy. This association faded over time and became nonsignificant (21.41 kg; 95% CI: 23.03, 0.21 kg) after 15 y. The results remained stable in sensitivity analyses that accounted for changes in IOM criteria over time and potential effect modification by low social class. A funnel plot did not suggest publication bias. Conclusion: GWG in accordance with the IOM recommendations is associated with long-term effects on PPWR.Am J Clin Nutr 2011;94:1225-31.