title: Hemoglobin concentrations influence birth outcomes in pregnant African-American adolescents.
abstract: Relationships between hemoglobin concentrations and birth outcomes have not been well characterized in African-American adolescents despite the fact that this group is at a higher risk of early childbearing. To address this issue, we characterized the prevalence of anemia and maternal factors associated with anemia in pregnant African-American adolescents. A retrospective medical chart review was undertaken of 918 adolescents who had received prenatal care at an inner-city maternity clinic between 1990 and 2000. Multiple log-linear regression analyses were used to address relationships between hemoglobin and adverse birth outcomes. The prevalence of anemia during the third trimester averaged 57-66% and was substantially higher than typically reported in adolescent and adult women. Multiparity, inadequate prenatal care, low prepregnancy BMI, history of self-reported cigarette use and infection with sexually transmitted diseases were significantly associated with lower hemoglobin during pregnancy. Adolescents with pre-eclampsia had higher hemoglobin (P < 0.01). Compared with the reference group (106-120 g/L), high hemoglobin (>120 g/L) during the second and third trimester significantly increased the risk of low birth weight (risk ratio (RR) = 3.11; [CI] 1.35, 7.13), and in the second-trimester cohort only, high hemoglobin concentrations increased the risk of preterm delivery (RR = 2.33; [CI] 1.07, 5.05). A U-shaped distribution between hemoglobin concentration and adverse birth outcomes was found in the third-trimester cohort when the reference range was decreased to 96-105 g/L to adjust for potentially lower hemoglobin concentrations among the African-American population. Our results suggest that additional medical attention may be warranted in pregnant African-American adolescents with hemoglobin concentrations of <or=95 g/L or >120 g/L.
authors.affiliation: Department of International Health, Center for Human Nutrition, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205-2179, USA.
authors.forename: Shih-Chen
authors.initials: SC
authors.lastname: Chang
authors.forename: Kimberly O
authors.initials: KO
authors.lastname: O'Brien
authors.forename: Maureen Schulman
authors.initials: MS
authors.lastname: Nathanson
authors.forename: Jeri
authors.initials: J
authors.lastname: Mancini
authors.forename: Frank R
authors.initials: FR
authors.lastname: Witter
mesh_terms: D000293:Adolescent; D000740:Anemia / Q000150:complications / Q000503:physiopathology; D015331:Cohort Studies; D005260:Female; D006400:Hematocrit; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000503:physiopathology; D011256:Pregnancy Outcome; D011253:Pregnancy in Adolescence; D012189:Retrospective Studies
chemical_list: D006454:Hemoglobins