Justiina Ronkainen1, Estelle Lowry2, Anni Heiskala2, Iida Uusitalo2, Peppi Koivunen3, Eero Kajantie4, Marja Vääräsmäki5, Marjo-Riitta Järvelin6, Sylvain Sebert7. 1. Center for Life Course Health Research, University of Oulu, Oulu, Finland; Biocenter Oulu, University of Oulu, Oulu, Finland. Electronic address: justiina.ronkainen@oulu.fi. 2. Center for Life Course Health Research, University of Oulu, Oulu, Finland; Biocenter Oulu, University of Oulu, Oulu, Finland. 3. Biocenter Oulu, University of Oulu, Oulu, Finland; Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland; Oulu Center for Cell-Matrix Research, University of Oulu, Oulu, Finland. 4. PEDEGO Research Unit, MRC Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland; Public Health Promotion Unit, Department of Public Health Solutions, National Institute for Health and Welfare, Helsinki, Finland; Hospital for Children and Adolescents, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland; Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway. 5. PEDEGO Research Unit, MRC Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland; Public Health Promotion Unit, Department of Public Health Solutions, National Institute for Health and Welfare, Helsinki, Finland. 6. Center for Life Course Health Research, University of Oulu, Oulu, Finland; Biocenter Oulu, University of Oulu, Oulu, Finland; Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, United Kingdom; MRC-PHE Centre for Environment and Health, School of Public Health, Imperial College London, London, United Kingdom. 7. Center for Life Course Health Research, University of Oulu, Oulu, Finland; Biocenter Oulu, University of Oulu, Oulu, Finland; Department for Genomics of Common Diseases, School of Medicine, Imperial College London, London, United Kingdom.
Abstract
OBJECTIVE: To test whether maternal hemoglobin during pregnancy associates with offspring perinatal outcomes in a developed country. Changes in maternal hemoglobin concentration during pregnancy are partly physiological phenomena reflecting alterations of maternal blood volume. Especially hemoglobin measures outside the physiological range may influence maternal health and fetal growth with long-lasting consequences. STUDY DESIGN: We studied an unselected sample drawn from two regional birth cohorts born 20 years apart: The Northern Finland Birth Cohorts 1966 and 1986. These are two mother-and-child population-based birth cohorts together comprising 21,710 mothers and their children. After exclusions, the sample size of the current study was 20,554. Concentrations of maternal hemoglobin at first and last antenatal visits were categorized as low (lowest 10%), medium (reference) or high (highest 10%). Multinomial logistic regression analyses for categories of maternal hemoglobin and perinatal outcomes such as preterm delivery and full-term small and large for gestational age were conducted with adjustments for maternal cofactors. RESULTS: Low maternal hemoglobin at early pregnancy associated with decreased risk of full-term small for gestational age (adjusted OR 0.73, 95% CI [0.58, 0.93], p = 0.010). At late pregnancy, low maternal hemoglobin associated with increased risk of preterm delivery (adjusted OR 1.60, 95% CI [1.26, 2.02], p < 0.0005) whereas high maternal hemoglobin associated with increased risk of full-term small for gestational age (adjusted OR 1.29, 95% CI [1.07, 1.56], p = 0.009). Maternal hemoglobin did not show constant association with risk of large for gestational age. CONCLUSION: The results from this study support evidence that both low and high maternal hemoglobin associate with adverse perinatal outcomes. Low maternal hemoglobin associated with preterm delivery and high with full-term small for gestational age. Association was mainly present when maternal hemoglobin was measured during the third trimester. These results indicate that it is important to monitor both extremes of maternal hemoglobin throughout the pregnancy.
OBJECTIVE: To test whether maternal hemoglobin during pregnancy associates with offspring perinatal outcomes in a developed country. Changes in maternal hemoglobin concentration during pregnancy are partly physiological phenomena reflecting alterations of maternal blood volume. Especially hemoglobin measures outside the physiological range may influence maternal health and fetal growth with long-lasting consequences. STUDY DESIGN: We studied an unselected sample drawn from two regional birth cohorts born 20 years apart: The Northern Finland Birth Cohorts 1966 and 1986. These are two mother-and-child population-based birth cohorts together comprising 21,710 mothers and their children. After exclusions, the sample size of the current study was 20,554. Concentrations of maternal hemoglobin at first and last antenatal visits were categorized as low (lowest 10%), medium (reference) or high (highest 10%). Multinomial logistic regression analyses for categories of maternal hemoglobin and perinatal outcomes such as preterm delivery and full-term small and large for gestational age were conducted with adjustments for maternal cofactors. RESULTS: Low maternal hemoglobin at early pregnancy associated with decreased risk of full-term small for gestational age (adjusted OR 0.73, 95% CI [0.58, 0.93], p = 0.010). At late pregnancy, low maternal hemoglobin associated with increased risk of preterm delivery (adjusted OR 1.60, 95% CI [1.26, 2.02], p < 0.0005) whereas high maternal hemoglobin associated with increased risk of full-term small for gestational age (adjusted OR 1.29, 95% CI [1.07, 1.56], p = 0.009). Maternal hemoglobin did not show constant association with risk of large for gestational age. CONCLUSION: The results from this study support evidence that both low and high maternal hemoglobin associate with adverse perinatal outcomes. Low maternal hemoglobin associated with preterm delivery and high with full-term small for gestational age. Association was mainly present when maternal hemoglobin was measured during the third trimester. These results indicate that it is important to monitor both extremes of maternal hemoglobin throughout the pregnancy.