Table 2. Risk of Having a Child With Severe Language Delay According to Use of Maternal Folic Acid Supplements.
| No. (%) of Children | Odds Ratio (95% CI) | |||
|---|---|---|---|---|
| Overall (n = 37 664)a | With Severe Language Delay | Unadjusted (n = 37664)a | Adjusted (n = 35135)b | |
| Supplement use (4 wk before to 8 wk after conception) | ||||
| None | 9052 (24.0) | 81 (0.9) | 1 [Reference] | 1 [Reference] |
| Other supplements, no folic acid | 2480 (6.6) | 22 (0.9) | 0.99 (0.61-1.59) | 1.04 (0.62-1.74) |
| Folic acid only | 7127 (18.9) | 28 (0.4) | 0.43 (0.28-0.67) | 0.55 (0.35-0.86) |
| Folic acid plus other supplements | 19 005 (50.5) | 73 (0.4) | 0.42 (0.31-0.58) | 0.55 (0.39-0.78) |
| Initiation of folic acid (4 wk before to 17 wk after conception)c | ||||
| None | 6832 (18.1) | 63 (0.9) | 1 [Reference] | 1 [Reference] |
| Week −4 to −1 | 12 208 (32.4) | 39 (0.3) | 0.34 (0.23-0.51) | 0.48 (0.31-0.74) |
| Week 0 to 4 | 6819 (18.1) | 33 (0.5) | 0.52 (0.34-0.79) | 0.67 (0.42-1.06) |
| Week 5 to 8 | 7105 (18.9) | 29 (0.4) | 0.44 (0.28-0.68) | 0.64 (0.40-1.02) |
| Week 9 to 12 | 2547 (6.8) | 22 (0.8) | 0.93 (0.57-1.52) | 1.13 (0.66-1.92) |
| Week 13 to 17 | 2153 (5.7) | 18 (0.8) | 0.90 (0.53-1.53) | 1.18 (0.68-2.05) |
a
Excluding moderate language delay (n=1290).
b
Adjusted for maternal education, maternal body mass index, parity, and marital status. Moderate language delay (n=1290) and missing confounder data (n=2529) excluded from analysis.
c
The 4 exposure categories in supplement use collapsed into “no/yes,” with “no” indicating no use of folic acid (no supplements and other supplements, no folic acid) and “yes” indicating use of folic acid (folic acid only and folic acid plus other supplements). No use of folic acid in the period 4 weeks before to 17 weeks after conception is the reference group of use of folic acid in 5 intervals, with weeks −4 to 17 defining the 5 exposed groups.