Abstract
BackgroundAnaemia in pregnancy is a global health problem with associated morbidity and mortality.MethodsA secondary analysis of prospective, population-based study from 2009 to 2016 to generate maternal haemoglobin normative centiles in uncomplicated pregnancies in women receiving optimal antenatal care. Pregnant women were enrolled <14 weeks’ gestation in the Fetal Growth Longitudinal Study (FGLS) of the INTERGROWTH-21st Project which involved eight geographically diverse urban areas in Brazil, China, India, Italy, Kenya, Oman, United Kingdom and United States. At each 5 ± 1 weekly visit until delivery, information was collected about the pregnancy, as well as the results of blood tests taken as part of routine antenatal care that complemented the study's requirements, including haemoglobin values.FindingsA total of 3502 (81%) of 4321 women who delivered a live, singleton newborn with no visible congenital anomalies, contributed at least one haemoglobin value. Median haemoglobin concentrations ranged from 114.6 to 121.4 g/L, 94 to 103 g/L at the 3rd centile, and from 135 to 141 g/L at the 97th centile. The lowest values were seen between 31 and 32 weeks’ gestation, representing a mean drop of 6.8 g/L compared to 14 weeks’ gestation. The percentage variation in maternal haemoglobin within-site was 47% of the total variance compared to 13% between sites.InterpretationWe have generated International, gestational age-specific, smoothed centiles for maternal haemoglobin concentration compatible with better pregnancy outcomes, as well as adequate neonatal and early childhood morbidity, growth and development up to 2 years of age.FundingBill & Melinda Gates Foundation Grant number 49038.
Highlights
Anaemia in pregnancy is a global nutritional problem associated with increased risks of maternal mortality [1], Caesarean section [2], low birth weight (LBW), small-for-gestational age, preterm birth, and perinatal and neonatal mortality [3,4]
Our study provides evidence to help inform re-examination of World Health Organization (WHO) haemoglobin cut-off points for defining anaemia in pregnancy
In 1958, a WHO Study Working Group on Iron Deficiency Anaemia met in Geneva, Switzerland and determined that, for adult pregnant women, haemoglobin (Hb) concentrations below 100 g/L were indicative of anaemia [10]
Summary
Anaemia in pregnancy is a global nutritional problem associated with increased risks of maternal mortality [1], Caesarean section [2], low birth weight (LBW), small-for-gestational age, preterm birth, and perinatal and neonatal mortality [3,4]. This paper provides, for the first time, normative Hb trajectories to establish gestational age-specific distributions that are compatible with functional health outcomes up to 2 years of age, as well as normal population thresholds for Hb in pregnancy. These parameters complement the international standards for early and late fetal growth, maternal weight gain, symphysis fundal height, and newborn size and body composition produced from the same FGLS data set [29À34]
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