Table 5 Comparison of mean weight gain velocity between the PreM Growth Study cohorts and fetal-infant estimate

Birth to 2 weeks postnatal age

23-25 weeks

3.8

6.6

193

18.2

−14.4

<0.0001

26-28 weeks

2.5

5.0

429

18.0

−15.5

<0.0001

29-31 weeks

6.8

4.8

160

17.3

−10.5

<0.0001

Gain 2 weeks after birth to 37 weeks

23-25 weeks

13.3

1.7

168

16.1

−2.8

<0.0001

26-28 weeks

14.3

2.2

381

15.4

−1.1

<0.0001

29-31 weeks

14.9

2.8

144

13.5

1.4

0.46

Gain 37 to 40* weeks (40 weeks based on the FIGR-2013)

23-25 weeks

11.5

3.4

140

7.5

4.0

<0.0001

26-28 weeks

11.4

3.1

314

7.5

3.9

<0.0001

29-31 weeks

12.3

3.8

124

7.5

4.8

<0.0001

40 to 50 weeks (40 weeks based on the FIGR-2013)

23-25 weeks

6.9

1.7

101

6.5

0.4

0.016

26-28 weeks

7.0

1.6

256

6.5

0.5

<0.0001

29-31 weeks

6.7

1.3

100

6.5

0.2

0.09

40 to 50 weeks (40 weeks based on the WHO Growth Standard)

23-25 weeks

6.9

1.5

101

7.4

−0.5

<0.0001

26-28 weeks

7.0

1.4

256

7.4

−0.4

<0.0001

29-31 weeks

6.7

1.2

100

7.4

−0.7

<0.0001