Table 4 Risk of preterm birth strata by gestational age (weeks) according to maternal age (years) among multiples. Lombardy, Italy, 2007–2017

6884 (51.7)

38 (63.3)

213 (56.3)

924 (51.1)

2597 (51.9)

800 (57.3)

1.75 (1.00–3.08)

1.43 (1.14–1.80)

1.09 (0.97–1.22)

1.06 (0.98–1.16)

1.37 (1.20–1.55)

1.79 (1.01–3.17)

1.47 (1.16–1.85)

1.11 (0.98–1.24)

1.06 (0.98–1.16)

1.36 (1.19–1.55)

1068 (8.0)

4 (6.7)

41 (10.8)

181 (10.0)

375 (7.5)

111 (7.9)

1.20 (0.40–3.57)

1.78 (1.23–2.56)

1.39 (1.14–1.69)

1.00 (0.85–1.17)

1.23 (0.97–1.56)

0.83 (0.24–2.86)

1.80 (1.23–2.63)

1.39 (1.13–1.70)

0.97 (0.83–1.14)

1.11 (0.87–1.41)