Objective: To determine the outcomes of pregnancies affected by hemoglobin H (HbH) disease. Methods: A retrospective cohort study was conducted with 120 women with singleton pregnancies complicated by HbH disease only. The controls-to-cases ratio was 2:1. Results: Maternal outcomes were similar in the 2 groups. The incidences of fetal growth restriction (relative risk [RR], 2.4; 95% confidence interval [CI], 1.60-3.50), preterm birth (RR, 1.4; 95% CI, 1.03-1.96), and low birth weight (RR, 1.9; 95% CI, 1.46-2.56) were significantly higher in the study than in the control group. The perinatal mortality rate was slightly higher in the study group. Conclusion: In spite of attempts to keep hemoglobin levels sufficiently high (> 7.0 g/dL), pregnancies with HbH disease were significantly associated with increased risks of fetal growth restriction, preterm birth, and low birth weight. © 2008 Elsevier Ireland Ltd. All rights reserved.