title: Risk factors and consequences of maternal anaemia and elevated haemoglobin levels during pregnancy: a population-based prospective cohort study.
abstract: BACKGROUND
  To determine sociodemographic and life style-related risk factors and trimester specific maternal, placental, and fetal consequences of maternal anaemia and elevated haemoglobin levels in pregnancy.
  
  
  METHODS
  In a population-based prospective cohort study of 7317 mothers, we measured haemoglobin levels in early pregnancy [gestational age median 14.4 weeks (inter-quartile-range 12.5-17.5)]. Anaemia (haemoglobin ≤11 g/dl) and elevated haemoglobin levels (haemoglobin ≥13.2 g/dl) were defined according to the WHO criteria. Maternal blood pressure, placental function and fetal growth were measured in each trimester. Data on gestational hypertensive disorders and birth outcomes was collected from hospitals.
  
  
  RESULTS
  Older maternal age, higher body mass index, primiparity and European descent were associated with higher haemoglobin levels (P < 0.05). Elevated haemoglobin levels were associated with increased systolic and diastolic blood pressure throughout pregnancy (mean differences 5.1 mmHg, 95% confidence interval [CI] 3.8, 6.5 and 4.1 mmHg, 95% CI 3.0, 5.2, respectively) and with a higher risk of third trimester uterine artery notching (RR 1.3, 95% CI 1.0, 1.7). As compared with maternal normal haemoglobin levels, not anaemia, but elevated haemoglobin levels were associated with fetal head circumference, length, and weight growth restriction from third trimester onwards (P < 0.05). Elevated haemoglobin levels were associated with increased risks of gestational hypertensive disorders (RR 1.4, 95% CI 1.1, 1.8) and adverse birth outcomes (RR 1.4, 95% CI 1.1, 1.7).
  
  
  CONCLUSIONS
  In a low-risk population, various sociodemographic and life style factors affect haemoglobin levels during pregnancy. Elevated haemoglobin levels are associated with increased risks of maternal, placental, and fetal complications.
authors: The Generation R Study Group, Erasmus Medical Center - Sophia Children's Hospital, Rotterdam, the Netherlands; Department of Epidemiology, Erasmus Medical Center - Sophia Children's Hospital, Rotterdam, the Netherlands; Department of Paediatrics, Erasmus Medical Center - Sophia Children's Hospital, Rotterdam, the Netherlands.
authors: Romy
authors: R
authors: Gaillard
authors: Paul H C
authors: PH
authors: Eilers
authors: Siham
authors: S
authors: Yassine
authors: Albert
authors: A
authors: Hofman
authors: Eric A P
authors: EA
authors: Steegers
authors: Vincent W V
authors: VW
authors: Jaddoe
mesh_terms: D000328:Adult; D000740:Anemia / Q000453:epidemiology / Q000378:metabolism* / Q000517:prevention & control; D015992:Body Mass Index; D004522:Educational Status; D005260:Female; D047109:Fetal Development; D005865:Gestational Age; D006400:Hematocrit / Q000379:methods*; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn; D008019:Life Style; D008423:Maternal Age; D010298:Parity; D010927:Placental Insufficiency / Q000453:epidemiology / Q000378:metabolism* / Q000517:prevention & control; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000453:epidemiology / Q000378:metabolism* / Q000517:prevention & control; D011256:Pregnancy Outcome; D011264:Pregnancy Trimesters; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D006454:Hemoglobins
keywords: adverse birth outcomes; blood pressure; cohort study; fetal growth; gestational hypertension; haemoglobin; pre-eclampsia; pregnancy