Table 2 Association between ambient temperature during the last four weeks before delivery and preterm birth by individual characteristics

Overall

1.03 (1.02, 1.05)

1.06 (1.01, 1.12)

1.03 (1.01, 1.05)

Maternal age

 <35 years

1.02 (1.00, 1.04)

1.04 (0.98, 1.10)

1.02 (1.00, 1.04)

 ≥35 years

1.06 (1.03, 1.10)

1.12 (1.02, 1.23)

1.06 (1.02, 1.09)

Parity

 Primiparity

1.03 (1.01, 1.06)

1.11 (1.03, 1.19)

1.02 (1.00, 1.05)

 Multiparity

1.03 (1.01, 1.06)

1.01 (0.93, 1.10)

1.03 (1.00, 1.06)

Maternal education level

 ≤ College

1.04 (1.02, 1.05)

1.06 (1.01, 1.12)

1.03 (1.01, 1.05)

 > College

1.00 (0.94, 1.07)

1.09 (0.87, 1.36)

0.99 (0.93, 1.06)

Classification of prematurity^a

 Late to moderate preterm

1.03 (1.01, 1.05)

1.08 (1.02, 1.13)

1.03 (1.01, 1.05)

 Very to extreme preterm

1.03 (0.98, 1.08)

0.97 (0.83, 1.12)

1.04 (0.99, 1.10)