Pregnancy Outcomes Among Women with Homozygous Hemoglobin E Disease: A Retrospective Cohort Study.

Background Homozygous hemoglobin E (HbE) disease is common, especially in Southeast Asia where the prevalence may be as high as nearly 1 % of pregnancies and it is usually associated with mild anemia. Nevertheless, the effects of the disease on pregnancy outcomes have never been explored. Objective To compare the obstetric adverse outcomes between singleton pregnancies complicated with HbE disease and normal controls. Patients and Methods A retrospective cohort study was undertaken by assessment of the database of maternal-fetal medicine units, Chiang Mai University, Thailand, from January 2000 to December 2014 to search for the records of pregnant women complicated by the disease. The records of low risk pregnancies were randomly selected as a control group with a ratio of 10:1. Pregnancies with underlying medical diseases or fetal abnormalities as well as those with no complete data were excluded. Result During the study period, 78 women with homozygous HbE disease (study group) and 780 normal controls were recruited. Most baseline characteristics of the two groups were similar. The mean birth weight was significantly lower in the study group (2683 ± 627 vs 2925 ± 623 g, P = 0.001).The prevalence of fetal growth restriction was also significantly higher in the study group (13.2 vs 6.7 %, P = 0.040, relative risk 1.96; 95 % CI 1.04-3.69), whereas the rates of other outcomes such as preterm birth were comparable. Conclusion for Practice Homozygous HbE disease does not increase risk of common adverse pregnancy outcomes, but it significantly increases risk of fetal growth restriction, resulting in significantly lower mean birth weight.