Table 1 Total population changes in haemoglobin concentration between the first and 3rd trimesters and stratified sub-groups by distribution of haemoglobin

1st Trimester Hb 3rd Trimester Hb
Sample N mean SD IQ 5/95% N mean SD IQ 5/95% ΔHB(%)
Total Population 7054 127.9 11.2 121–134 108/143 6642 113.7 10.3 107–121 96/130 −14.2(11)
Population 5th- 95th centile 6078 127.0 7.9 122–133   5745 113.0 9.5 117–120   −14.4 (11.3)
Subgroup A ƒ 4224 130 8.8 124–136 116/144 4028 115.6 9.2 110–122 101/131 −14.4 (11.0)
Subgroup B ƒƒ 5876 129.4 8.8 123–135 115/144 5476 114.7 9.6 109–121 99/130 −14.7(11.4)
Subgroup C 5th -95th centile &a 1958 128.1 7.86 123–134 115/140 1855 114.2 9.4 108–121 98/129 −13.9(10.9)
Subgroup D 5th–100th centile &a 2103 129.4 9.18 123–136 114/144 2035 114.8 9.75 109–121 98/130 −14.6(11.3)
Subgroup E = < 5 centile &a 78 98.7 9.59 95–106 74/107 57 108.8 12.7 99–119 89/128 + 10.1(10.2)
Subgroup F 5th–95th centile &a 1303 130 7.0 126–136 118.141 1303 118 6.2 114–123 110/130 −10.2 (7.8)
Subgroup EG > 95th centile &a 145 147.8 5.07 144–149 1143/158 180 121.2 11.03 114–137 103/137 −26.6(18.0)
1. ΔHB(%) – represents the absolute change in haemoglobin and the percentage change in brackets
2. Each subgroup represents the total population excluding the women as shown by the symbols below
3. a Restricting the sample to pregnant women without the following problems during index pregnancy current pregnancy problems, pregnancy induced hypertension, Pre-term birth, antepartum haemorrhage, pre-pregnancy med problems, diabetes, hypertension, renal disease, & anaemia in 1st trimester
4. ƒ excludes anaemic women and women with a serum ferritin <30mcg/L in the first trimester
5. ƒƒexcludes anaemic women and women with a serum ferritin <15mcg/L in the first trimester