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Data-sets concerning lactation performance were selected for meta-analysis using the following criteria: (a) inclusion of the necessary maternal anthropometry to calculate BMI; and (b) inclusion of measurements of breast-milk output (and, wherever available, milk quality) performed by acceptable methods between 2 and 6 months post partum (representing the time of peak milk flow). Many older studies have been excluded from the analysis because we have previously demonstrated that inadequate measurement protocols and biased sampling procedures invalidate their results (Prentice et al., 1986). The sources used are listed in Table 1 in ascending order of BMI. There is a total of 1726 measurements from 41 groups.
Correspondence to: Dr A. M. Prentice, Dunn Clinical Nutrition Centre, Hill's Road, Cambridge CB2 2DH, UK.
Table 1. Datasets included in the analysis
|
Reference |
Country |
n |
Maternal height |
Maternal weight |
Maternal BMI |
Stage post partum |
Milk volume |
Energy content |
|
Khin-Muang-Naing et al. (1980) |
Myanmar (Burma) |
14 |
1.50 |
- |
<16.8 |
1-4 |
767±94 |
2.70 |
|
Khin-Muang-Naing et al. (1980) |
Myanmar (Burma) |
37 |
1.50 |
- |
16.8-18.9 |
1-4 |
792 ± 213 |
2.58 |
|
Brown et al. (1986) |
Bangladesh |
14 |
1.48 |
39.1 |
17.9 |
5 |
750 ± 63 |
2.55 |
|
Steenbergen et al. (1989) |
Java (HE supp) |
53 |
1.51 |
41.7 |
18.3 |
3-4 |
743 ± 130 |
N/A |
|
Steenbergen et al. (1989) |
Java (LE supp) |
54 |
1.51 |
42.0 |
18.4 |
3-4 |
744 ± 120 |
N/A |
|
Steenbergen et al. (1983) |
Kenya (WH-minus) |
46 |
1.57 |
46.0 |
18.7 |
2 |
827 ± 192 |
.241 |
|
Khin-Muang-Naing et al. (1980) |
Myanmar (Burma) |
22 |
1.50 |
- |
19-21.2 |
1-4 |
815 ± 188 |
2.73 |
|
Orr-Ewing et al. (1986) |
Papua New Guinea |
22 |
- |
- |
19.2-25.9 |
4-6 |
863 ± 157 |
2.72 |
|
Madhavapeddi et al. (1992) |
India |
8 |
1.53 |
44.8 |
19.0 |
2 |
703 ± 191 |
N/A |
|
WHO (1985) |
Philippines (C) |
28 |
1.53 |
47.1 |
20.1 |
3 |
622 ± 221 |
2.56 |
|
Prentice et al. (1986) |
The Gambia |
183 |
1.58 |
51.0 |
20.4 |
3 |
782 ± 165 |
2.93 |
|
WHO (1985) |
Zaire (rural) |
73 |
- |
- |
20.5 |
1.5 |
307 ± 138 |
N/A |
|
Lovelady et al. (1990) |
USA (non-exercise) |
8 |
1.66 |
57.4 |
20.7 |
4 |
776 ± 144 |
2.52 |
|
WHO (1985) |
Zaire (C) |
57 |
1.57 |
51.1 |
20.7 |
3 |
356 ± 173 |
2.65 |
|
Frigerio et al. (1991) |
The Gambia |
16 |
1.61 |
53.9 |
20.9 |
2.5 |
738 ± 188 |
N/A |
|
WHO (1985) |
Philippines (A) |
20 |
1.51 |
47.6 |
21.0 |
3 |
320 ± 200 |
2.55 |
|
Lovelady et al. (1990) |
USA (exercise) |
8 |
1.67 |
59.3 |
21.1 |
4 |
839 ± 175 |
2.52 |
|
WHO (1985) |
Sweden |
28 |
1.67 |
59.3 |
21.2 |
3 |
776 ± 95 |
3.34 |
|
Prentice et al. (1986) |
UK |
48 |
1.63 |
56.7 |
21.3 |
4 |
783 ± 176 |
2.93 |
|
Khin-Muang-Naing et al. (1980) |
Myanmar (Burma) |
17 |
1.50 |
- |
>21.3 |
1-4 |
934 ± 194 |
2.70 |
|
WHO (1985) |
Philippines (B) |
32 |
1.50 |
48.5 |
21.5 |
3 |
639 ± 117 |
2.69 |
|
Goldberg et al. (1991) |
UK |
10 |
1.64 |
58.6 |
21.8 |
3 |
791 ± 176 |
N/A |
|
WHO (1985) |
Guatemala (C) |
27 |
1.50 |
50.4 |
22.1 |
3 |
686 ± 151 |
2.35 |
|
Sadurskis et al. (1988) |
Sweden |
23 |
1.66 |
61.2 |
22.2 |
2 |
740 ± 150 |
N/A |
|
van Raaiji et al. (1991) |
Netherlands |
16 |
1.70 |
64.2 |
22.2 |
3 |
746 ± 175 |
N/A |
|
Hennart et al. (1991) |
Zaire (urban) |
54 |
- |
- |
22.6 |
1.5 |
612 ± 198 |
N/A |
|
Hennart et al. (1980) |
Zaire (rural) |
166 |
1.50 |
51.2 |
22.7 |
6 |
489 ± 29 |
N/A |
|
Hennart et al. (1980) |
Zaire (rural) |
23 |
1.53 |
53.3 |
22.8 |
6 |
390 ± 93 |
N/A |
|
Hennart et al. (1980) |
Zaire (rural) |
148 |
1.52 |
52.9 |
22.9 |
6 |
611 ± 41 |
N/A |
|
Butte et al. (1988) |
USA |
9 |
1.64 |
61.6 |
22.9 |
3.6 |
642 ± 210 |
N/A |
|
Motil et al. (1989) |
USA |
4 |
1.66 |
63.0 |
22.9 |
5 |
786 ± 109 |
N/A |
|
WHO (1985) |
Guatemala (B) |
30 |
1.49 |
50.7 |
22.9 |
3 |
548 ± 173 |
2.53 |
|
WHO (1985) |
Guatemala (A) |
28 |
1.57 |
56.5 |
23.0 |
3 |
653 ± 255 |
2.37 |
|
Butte et al. (1991) |
USA |
20 |
1.63 |
64.0 |
24.1 |
4 |
858 ± 172 |
N/A |
|
WHO (1985) |
Hungary |
85 |
1.61 |
62.4 |
24.2 |
3 |
681 ± 168 |
2.51 |
|
WHO (1985) |
Zaire (B) |
99 |
1.53 |
57.0 |
24.3 |
3 |
588 ± 202 |
2.41 |
|
Butte et al. (1992), Villalpando et al. (1991) |
Mexico |
30 |
1.47 |
50.3 |
23.4 |
4 |
885 ± 145 |
2 34 |
|
Nommsen et al. (1991) |
USA |
58 |
1.66 |
64.5 |
23.4 |
3 |
811 ± 133 |
273 |
|
Hennart et al. (1983) |
Zaire (urban) |
46 |
1.54 |
55.8 |
23.5 |
3-5 |
681 ± 185 |
N/A |
|
Steenbergen et al. (1983) |
Kenya (WH plus) |
52 |
11.56 |
57.4 |
23.6 |
2 |
741 ± 219 |
2.15 |
|
Infante et al. (1985) |
Chile |
10 |
1.51 |
54.1 |
23.7 |
2 |
961 + 120 |
N/A |
Milk volumes are expressed as means ± SD. BMI = body mass index. 'HE supp' and 'LE supp' refer to high-energy and low-energy supplemented mothers. 'WH-minus' and 'WH-plus' refer to low and high weight-for-height mothers. Letters refer to sub-groupings in original report: Guatemala, A = well-to-do mothers, B = urban poor mothers, C = rural mothers; Philippines, same as Guatemala; Zaire, A = urban mothers, B = rural mothers. N/A = not available.