TABLE 5.
Supplementary iron intake and fecundability among women planning a pregnancy in the Snart Foraeldre and PRESTO cohorts1
| Pregnancies, n | Cycles at risk, n | Age-adjusted FR (95% CI) | Multivariable model2 FR (95% CI) | |
|---|---|---|---|---|
| Snart Foraeldre, n = 1693 | ||||
| Iron-containing supplements | ||||
| Nonuser | 453 | 2494 | 1.00 (Ref.) | 1.00 (Ref.) |
| Any iron-containing supplement user | 686 | 3672 | 1.06 (0.95, 1.18) | 1.01 (0.90, 1.13) |
| Supplement type | ||||
| Nonuser | 453 | 2494 | 1.00 (Ref.) | 1.00 (Ref.) |
| Multivitamin user | 616 | 3346 | 1.05 (0.94, 1.17) | 1.01 (0.90, 1.13) |
| Iron-only supplement user | 70 | 326 | 1.15 (0.92, 1.44) | 1.05 (0.84, 1.32) |
| PRESTO, n = 2969 | ||||
| Iron-containing supplements | ||||
| Nonuser | 185 | 1559 | 1.00 (Ref.) | 1.00 (Ref.) |
| Any iron-containing supplement user | 1631 | 10,841 | 1.25 (1.08, 1.43) | 1.19 (1.03, 1.38) |
| Supplement type | ||||
| Nonuser | 185 | 1559 | 1.00 (Ref.) | 1.00 (Ref.) |
| Multivitamin user | 1436 | 9509 | 1.25 (1.08, 1.44) | 1.19 (1.03, 1.38) |
| Iron-only supplement user | 195 | 1332 | 1.23 (1.02, 1.48) | 1.20 (0.99, 1.44) |
1
FR, fecundability ratio
2
Adjusted for age, vocational training/education, BMI, physical activity, smoking, alcohol consumption, use of oral contraceptives, cycle regularity and length, doing something to improve chances of conception, use of vitamin C supplements, and dietary vitamin C (continuous). The PRESTO models are also adjusted for race/ethnicity.