Table 3 Associations of GWG with preterm birth, post-term birth, and total adverse outcome in different pre-pregnancy BMI populations

Underweight (n = 84,657)

 Levels of weight-gain-for-gestational-age z-scores

  Quantile 1

1.27 (1.16–1.38)

< 0.001

1.28 (1.16–1.42)

< 0.001

1.23 (1.15–1.31)

< 0.001

  Quantile 2

Ref

Ref

Ref

  Quantile 3

1.47 (1.38–1.56)

< 0.001

0.85 (0.79–0.92)

< 0.001

1.23 (1.17–1.29)

< 0.001

  Quantile 4

2.88 (2.72–3.06)

< 0.001

0.60 (0.55–0.65)

< 0.001

1.90 (1.81–1.99)

< 0.001

 Weight-gain-for-gestational-age z-scores

11.77 (10.51–13.17)

< 0.001

0.31 (0.26–0.36)

< 0.001

4.30 (3.90–4.73)

< 0.001

Normal (n = 1,183,961)

 Levels of Weight-gain-for-gestational-age z-scores

  Quantile 1

1.17 (1.15–1.20)

< 0.001

1.19 (1.16–1.22)

< 0.001

1.13 (1.11–1.15)

< 0.001

  Quantile 2

Ref

Ref

Ref

  Quantile 3

1.46 (1.43–1.49)

< 0.001

0.80 (0.78–0.82)

< 0.001

1.14 (1.12–1.16)

< 0.001

  Quantile 4

3.07 (3.02–3.13)

< 0.001

0.56 (0.54–0.57)

< 0.001

1.78 (1.75–1.80)

< 0.001

 Weight-gain-for-gestational-age z-scores

11.88 (11.49–12.28)

< 0.001

0.33 (0.32–0.34)

< 0.001

3.31 (3.22–3.40)

< 0.001

Overweight (n = 766,211)

 Levels of Weight-gain-for-gestational-age z-scores

  Quantile 1

1.00 (0.98–1.03)

0.978

1.18 (1.15–1.21)

< 0.001

1.04 (1.02–1.06)

< 0.001

  Quantile 2

Ref

Ref

Ref

  Quantile 3

1.40 (1.37–1.44)

< 0.001

0.88 (0.85–0.90)

< 0.001

1.17 (1.15–1.20)

< 0.001

  Quantile 4

2.64 (2.59–2.70)

< 0.001

0.62 (0.60–0.64)

< 0.001

1.72 (1.69–1.75)

< 0.001

 Weight-gain-for-gestational-age z-scores

5.71 (5.53–5.90)

< 0.001

0.50 (0.48–0.52)

< 0.001

2.37 (2.31–2.43)

< 0.001

Obesity (n = 772,436)

 Levels of Weight-gain-for-gestational-age z-scores

  Quantile 1

0.96 (0.94–0.98)

< 0.001

1.18 (1.16–1.21)

< 0.001

1.02 (1.01–1.04)

0.011

  Quantile 2

Ref

Ref

Ref

  Quantile 3

1.44 (1.41–1.47)

< 0.001

0.89 (0.86–0.92)

< 0.001

1.23 (1.20–1.25)

< 0.001

  Quantile 4

2.55 (2.50–2.61)

< 0.001

0.62 (0.60–0.64)

< 0.001

1.78 (1.75–1.81)

< 0.001

 Weight-gain-for-gestational-age z-scores

3.30 (3.23–3.38)

< 0.001

0.59 (0.58–0.61)

< 0.001

1.81 (1.78–1.85)

< 0.001