Table 1 Meta-analysis of the association between low maternal Hb and infant outcomes

Timing: low maternal Hb (< 110 g/L) by timing

Preconception

1.72^b

(1.31–2.26)

--

1.04

(0.97–1.12)

1.79^b

(1.39–2.31)

1.23^a

(0.39–3.86)

--

--

First trimester

1.31

(1.16–1.49)

3.21^a

(1.06–9.71)

1.22

(1.15–1.31)

1.12

(1.04–1.21)

1.54

(1.12–2.12)

1.61

(0.80–3.24)

1.30^b

(0.92–1.84)

Second trimester

0.96

(0.72–1.27)

--

1.37

(1.15–1.64)

1.05

(0.94–1.19)

2.22

(1.36–3.65)

1.38^b

(0.88–2.15)

--

Third trimester

1.45

(1.23–1.70)

2.20^a

(1.43–3.38)

1.49

(1.30–1.71)

0.89

(0.80–0.98)

1.59

(0.91–2.78)

1.13

(0.73–1.76)

0.90^a

(0.72–1.12)

Cutoff: low maternal Hb at any time during pregnancy by cutoff

≤ 70 g/L

2.06

(1.63–2.61)

2.85^a

(2.07–3.92)

2.08

(1.67–2.59)

1.22^b

(1.09–1.37)

2.85

(1.66–4.90)

4.41^a

(2.21–8.81)

1.83^b

(1.52–2.19)

≤ 80 g/L

1.89

(1.61–2.23)

2.85^a

(2.07–3.92)

1.89

(1.58–2.25)

1.31

(1.14–1.51)

2.27

(1.53–3.38)

3.82

(2.34–6.24)

1.62

(1.37–1.90)

≤ 90 g/L

1.70

(1.51–1.91)

4.95^b

(1.60-15.29)

1.60

(1.44–1.77)

1.26

(1.17–1.36)

2.01

(1.57–2.56)

2.66

(1.28–5.55)

1.46

(1.30–1.63)

≤ 100 g/L

1.35

(1.26–1.45)

2.87

(1.48–5.57)

1.49

(1.39–1.60)

1.13

(1.04–1.23)

1.73

(1.43–2.10)

2.06

(1.47–2.90)

1.37

(1.26–1.48)

≤ 110 g/L

1.28

(1.22–1.35)

2.15

(1.47–3.13)

1.35

(1.29–1.42)

1.10

(1.02–1.19)

1.43

(1.24–1.65)

1.75

(1.28–2.39)

1.25

(1.16–1.34)

Overall estimate*

< 110 g/L

1.28

(1.22–1.35)

2.15

(1.47–3.13)

1.35

(1.29–1.42)

1.10

(1.02–1.19)

1.43

(1.24–1.65)

1.75

(1.28–2.39)

1.25

(1.16–1.34)