Maternal anaemia and birth weight: a cross-sectional study from Jiangxi Province, China

Background Association between maternal haemoglobin (Hb) and low birth weight (LBW) remains a controversial topic, and data in China were sparse. Aims We aimed to investigate the association between maternal Hb and LBW among pregnant women in Jiangxi Province, China. Methods In this cross-sectional study, 1,029 participants were enrolled. Anaemia was classified according to World Health Organization's definition of anaemia in pregnancy. Logistic regression analysis was performed to evaluate the association between maternal Hb and LBW. Generalized additive model and smooth curve fitting (penalized spline method) were conducted to explore the exact shape of curve between them. Results The overall prevalence of anaemia was 58.2% in our study. A significantly higher risk of LBW was found in moderate anaemia subjects (odds ratio [OR] = 2.93; 95% confidence interval [CI]: 1.16-5.31) and severe anaemia subjects (OR = 63.86; 95% CI: 25.66-158.90) compared with maternal Hb concentration >100 g/L. The fully adjusted smooth curve fitting presented an L-shaped association between the maternal Hb and LBW, with a turning point at about 110 g/L. Subgroup analyses showed that stronger associations between maternal Hb and LBW were detected in pregnant women with high education, long duration of gestation and multiple antenatal visits (all P for interaction <0.05). Conclusions Anaemia in delivering women was associated with an elevated risk of LBW and the risk increased with the severity of anaemia, especially among pregnant women with high education, long duration of gestation and multiple antenatal visits from Jiangxi Province, China.