TABLE 3.
All Women |
Adjusted HR (95% CI)2 |
|||||
n | PTB | Crude HR | Adjusted HR (95% CI)2 | BMI <25 kg/m2 | BMI ≥25 kg/m2 | |
n (%) | ||||||
Nonuser | 11,503 | 604 (5.2) | 1.00 | |||
Multivitamin user (any) | 21,785 | 1013 (4.5) | 0.88 | 0.89 (0.80, 0.99) | 0.84 (0.73, 0.95) | 1.03 (0.84, 1.26) |
Preconception, postconception | ||||||
−, − | 11,503 | 604 (5.2) | 1.00 | |||
++, ++ | 8569 | 376 (4.3) | 0.83 | 0.89 (0.77, 1.02) | 0.82 (0.70, 0.97) | 1.05 (0.81, 1.35) |
+, ++ | 2281 | 124 (5.3) | 1.01 | 1.01 (0.82, 1.24) | 0.93 (0.73, 1.20) | 1.21 (0.83, 1.76) |
−, ++ | 4297 | 211 (4.8) | 0.93 | 0.92 (0.77, 1.08) | 0.90 (0.74, 1.10) | 0.93 (0.67, 1.28) |
− or +, − or + | 6638 | 302 (4.5) | 0.87 | 0.84 (0.72, 0.97) | 0.77 (0.65, 0.92) | 1.01 (0.77, 1.32) |
−, no use; +, 1–3 wk during the 6-wk interval; ++, 4–6 wk during the 6-wk interval.
Cox regression models were adjusted for age, parity, BMI, sociooccupational status, and smoking. P = 0.07 for the interaction between multivitamin use and overweight status (BMI, in kg/m2: ≥25).