Table 2:
Unadjusted association between BMI and self-reported months trying to get pregnant.
| BMI | Months trying to get pregnant | ||||
|---|---|---|---|---|---|
| 0–3 months | 4–6 months | 7–12 months | 13–24 months | >24 months | |
| PR (95% CI) | |||||
| Continuous BMI | 1.00 | 1.03 (1.01, 1.05) | 1.03 (1.01, 1.05) | 1.06 (1.04, 1.08) | 1.08 (1.06, 1.10) |
| Categorical BMI | |||||
| Underweight | 1.00 | 1.00 (0.60, 1.60) | 0.93 (0.54, 1.61) | 0.19 (0.05, 0.79) | 0.82 (0.39, 1.73) |
| Normal weight | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Overweight | 1.00 | 1.14 (0.88, 1.47) | 1.34 (1.02, 1.76) | 0.99 (0.68, 1.43) | 1.62 (1.16, 2.25) |
| Obese | 1.00 | 1.58 (1.22, 2.06) | 1.39 (1.03, 1.89) | 1.92 (1.36, 2.70) | 3.31 (2.43, 4.50) |
Pre-pregnancy BMI was calculated using birth certificate reported height and weight, and categorized in standard groups for underweight (<18.5 kg/m2); normal (18.5–24.9 kg/m2); overweight (25.0–29.9 kg/m2); and obese (30 kg/m2 or higher).