| LRTI, 0–6 months, | LRTI hospitalised,0–6 months, | LRTI, 6–18 months, | LRTI hospitalised,6–18 months, | |||||
| n = 1566 | n = 614 | n = 4240 | n = 893 | |||||
| % | aRR (95% CI) | % | aRR (95% CI) | % | aRR (95% CI) | % | aRR (95% CI) | |
| Folic acid in first trimester | ||||||||
| No | 5.1% | 1.00 (–) | 1.8% | 1.00 (–) | 13.1% | 1.00 (–) | 2.8% | 1.00 (–) |
| Yes | 5.1% | 1.11 (0.99 to 1.24) | 2.1% | 1.28 (1.06 to 1.55) | 13.7% | 1.08 (1.01 to 1.16) | 2.9% | 1.19 (1.02 to 1.40) |
| Folic acid after first trimester | ||||||||
| No | 5.3% | 1.00 (–) | 2.1% | 1.00 (–) | 13.5% | 1.00 (–) | 3.0% | 1.00 (–) |
| Yes | 5.0% | 0.98 (0.87 to 1.10) | 1.9% | 0.88 (0.73 to 1.06) | 13.6% | 1.00 (0.93 to 1.07) | 2.7% | 0.86 (0.74 to 1.01) |
*Exposures in first and after first trimester adjusted for each other, and in addition adjusted for other vitamins and cod liver oil in pregnancy, and for maternal age, maternal atopy, maternal smoking in pregnancy, maternal educational level, postnatal parental smoking, sex, parity, birth weight, season born and breast feeding. Estimates for age 6–18 months also adjusted for type of day care and supplement use at 6 months of age (cod liver oil and vitamins).
aRR, adjusted relative risks; LRTI, lower respiratory tract infection.