Fig. 2

Box plots of haemoglobin concentration from the whole group taken at four timepoints. First hospital appointment timepoint corresponds to a gestation of 9.9 (7.28) weeks. The third trimester timepoint corresponds 27.6 (1.88) weeks. The preoperative timepoint corresponds to 37.9 (2.79) weeks. The horizontal line in each box represents the median value, the limits of the box represent the lower 25th centile and the upper 75th centile. The whiskers represent the lowest and highest values. The dashed line perpendicular to the Y axis is the line marking 130 g/L, the threshold value below which anaemia is defined. The small rise in haemoglobin and fall in prevalence of anaemia in the preoperative sample may be partly explained by the effects of fasting on haemoglobin concentration