Association of cesarean delivery with anemia in infants and children in 2 large longitudinal Chinese birth cohorts.
BACKGROUND
Cesarean delivery may reduce placental-fetal transfusion and thus increase the risk of early childhood anemia compared with vaginal delivery, but this notion has not been carefully studied in longitudinal cohorts.


OBJECTIVE
The aim was to assess the association of cesarean delivery with anemia in infants and children in 2 longitudinal Chinese birth cohorts from different socioeconomic settings.


METHODS
Cohort 1 was recruited from 5 counties in northeastern China and cohort 2 from 21 counties or cities in southeastern China. Cohort 1 involved 17,423 infants born during 2006-2009 to mothers with early pregnancy baseline hemoglobin concentrations ranging from 100 to 177 g/L, whereas cohort 2 involved 122,777 children born during 1993-1996 to mothers with baseline hemoglobin concentrations ranging from 60 to 190 g/L. The main outcomes were anemia at 6 and 12 mo in cohort 1 and at 58 mo in cohort 2. Multiple logistic regressions were used to estimate adjusted ORs of anemia for cesarean compared with vaginal delivery. Stratified analyses were performed by pre- and postlabor cesarean delivery and according to maternal baseline hemoglobin concentration (≤109, 110-119, 120-129, and ≥130 g/L).


RESULTS
Cesarean delivery was not associated with anemia at 6 mo in cohort 1 (adjusted OR: 1.05; 95% CI: 0.93, 1.19); however, cesarean delivery was associated with increased anemia at 12 mo in cohort 1 (adjusted OR: 1.19; 95% CI: 1.04, 1.37) and at 58 mo in cohort 2 (adjusted OR: 1.11; 95% CI: 1.08, 1.15). The positive associations for anemia at 12 and 58 mo were consistent across maternal hemoglobin subgroups and persisted for cesarean delivery subtypes.


CONCLUSIONS
Cesarean delivery is likely associated with anemia in children, which suggests a possible need for exploring changes in obstetric care that might prevent anemia in cesarean-delivered children.
From the Institute of Reproductive and Child Health/Ministry of Health Key Laboratory of Reproductive Health (H-tL, R-wY, Y-bZ, and J-mL) and the Department of Epidemiology and Biostatistics (H-tL and J-mL), School of Public Health, Peking University Health Science Center, Beijing, China; the Departments of Pediatrics, Environmental Medicine, and Population Health, School of Medicine, Wagner School of Public Service, and Steinhardt School of Culture, Education, and Human Development, New York University, New York, NY (LT); and the Shanghai First Maternity and Infant Hospital (affiliated with Tongji University), Shanghai Women's Health Institute, Shanghai, China (L-pZ).
Hong-tian
HT
Li
From the Institute of Reproductive and Child Health/Ministry of Health Key Laboratory of Reproductive Health (H-tL, R-wY, Y-bZ, and J-mL) and the Department of Epidemiology and Biostatistics (H-tL and J-mL), School of Public Health, Peking University Health Science Center, Beijing, China; the Departments of Pediatrics, Environmental Medicine, and Population Health, School of Medicine, Wagner School of Public Service, and Steinhardt School of Culture, Education, and Human Development, New York University, New York, NY (LT); and the Shanghai First Maternity and Infant Hospital (affiliated with Tongji University), Shanghai Women's Health Institute, Shanghai, China (L-pZ).
Leonardo
L
Trasande
From the Institute of Reproductive and Child Health/Ministry of Health Key Laboratory of Reproductive Health (H-tL, R-wY, Y-bZ, and J-mL) and the Department of Epidemiology and Biostatistics (H-tL and J-mL), School of Public Health, Peking University Health Science Center, Beijing, China; the Departments of Pediatrics, Environmental Medicine, and Population Health, School of Medicine, Wagner School of Public Service, and Steinhardt School of Culture, Education, and Human Development, New York University, New York, NY (LT); and the Shanghai First Maternity and Infant Hospital (affiliated with Tongji University), Shanghai Women's Health Institute, Shanghai, China (L-pZ).
Li-ping
LP
Zhu
From the Institute of Reproductive and Child Health/Ministry of Health Key Laboratory of Reproductive Health (H-tL, R-wY, Y-bZ, and J-mL) and the Department of Epidemiology and Biostatistics (H-tL and J-mL), School of Public Health, Peking University Health Science Center, Beijing, China; the Departments of Pediatrics, Environmental Medicine, and Population Health, School of Medicine, Wagner School of Public Service, and Steinhardt School of Culture, Education, and Human Development, New York University, New York, NY (LT); and the Shanghai First Maternity and Infant Hospital (affiliated with Tongji University), Shanghai Women's Health Institute, Shanghai, China (L-pZ).
Rong-wei
RW
Ye
From the Institute of Reproductive and Child Health/Ministry of Health Key Laboratory of Reproductive Health (H-tL, R-wY, Y-bZ, and J-mL) and the Department of Epidemiology and Biostatistics (H-tL and J-mL), School of Public Health, Peking University Health Science Center, Beijing, China; the Departments of Pediatrics, Environmental Medicine, and Population Health, School of Medicine, Wagner School of Public Service, and Steinhardt School of Culture, Education, and Human Development, New York University, New York, NY (LT); and the Shanghai First Maternity and Infant Hospital (affiliated with Tongji University), Shanghai Women's Health Institute, Shanghai, China (L-pZ).
Yu-bo
YB
Zhou
From the Institute of Reproductive and Child Health/Ministry of Health Key Laboratory of Reproductive Health (H-tL, R-wY, Y-bZ, and J-mL) and the Department of Epidemiology and Biostatistics (H-tL and J-mL), School of Public Health, Peking University Health Science Center, Beijing, China; the Departments of Pediatrics, Environmental Medicine, and Population Health, School of Medicine, Wagner School of Public Service, and Steinhardt School of Culture, Education, and Human Development, New York University, New York, NY (LT); and the Shanghai First Maternity and Infant Hospital (affiliated with Tongji University), Shanghai Women's Health Institute, Shanghai, China (L-pZ).
Jian-meng
JM
Liu
D000328:Adult; D000740:Anemia / Q000453:epidemiology / Q000208:ethnology / Q000209:etiology* / Q000517:prevention & control; D018798:Anemia, Iron-Deficiency / Q000453:epidemiology / Q000208:ethnology / Q000209:etiology* / Q000517:prevention & control; D002585:Cesarean Section / Q000009:adverse effects*; D002664:Child Nutritional Physiological Phenomena; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D015331:Cohort Studies; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D007223:Infant; D007227:Infant Nutritional Physiological Phenomena; D008137:Longitudinal Studies; D008297:Male; D011247:Pregnancy; D015995:Prevalence; D011446:Prospective Studies; D012306:Risk; D012423:Rural Health / Q000208:ethnology; D012959:Socioeconomic Factors; D014504:Urban Health / Q000208:ethnology
anemia; cesarean delivery; children; cohort; infant