Pooled RRR* and 95% CI of folic acid supplement doses in the periconceptional period (first period)† of pregnancy among pregnant women, from the INMA Project, Spain (2003–2008)
| Women who took FAS, n (%) | Folic acid supplement use (in µg/day) during the first period† | ||||||
|---|---|---|---|---|---|---|---|
| 400–999 (mean=433.0) | <400, included non use (mean=141.8) | ≥1000 (mean=3104.6) | |||||
| 329 (14%) | 1336 (57%) | 666 (29%) | |||||
| n | n | RRR* (95% CI) | I2, %‡ | n | RRR* (95% CI) | I2, %‡ | |
| Maternal age, (years) | |||||||
| ≤30 | 161 | 722 | 1.00 | 281 | 1.00 | ||
| >30 | 168 | 614 | 0.90 (0.58 to 1.40) | 58.4 | 385 | 1.31 (0.82 to 2.10) | 58.5 |
| Maternal education | |||||||
| Primary school or less | 65 | 373 | 1.00 | 122 | 1.00 | ||
| Secondary school | 124 | 563 | 1.06 (0.73 to 1.52) | 0.0 | 283 | 1.31 (0.88 to 1.94) | 0.0 |
| University studies | 140 | 400 | 0.66 (0.44 to 0.98) | 27.3 | 261 | 0.91 (0.59 to 1.39) | 24.4 |
| Paternal education | |||||||
| Primary school or less | 96 | 525 | 1.00 | 208 | 1.00 | ||
| Secondary school | 164 | 557 | 0.70 (0.51 to 0.95) | 0.0 | 316 | 0.82 (0.59 to 1.15) | 0.0 |
| University studies | 69 | 254 | 0.97 (0.65 to 1.45) | 0.0 | 142 | 1.00 (0.65 to 1.54) | 0.0 |
| Tobacco smoking† | |||||||
| No | 289 | 1061 | 1.00 | 558 | 1.00 | ||
| Yes | 40 | 275 | 1.63 (1.11 to 2.39) | 0.0 | 108 | 1.36 (0.90 to 2.07) | 0.0 |
| Alcohol consumption† | |||||||
| No | 251 | 923 | 1.00 | 460 | 1.00 | ||
| Yes | 78 | 413 | 1.40 (1.02 to 1.92) | 39.1 | 206 | 1.42 (1.01 to 1.98) | 19.2 |
| Pre-pregnancy BMI | |||||||
| <25 | 241 | 969 | 1.00 | 499 | 1.00 | ||
| 25–29.9 | 60 | 253 | 0.95 (0.67 to 1.33) | 0.0 | 123 | 0.90 (0.62 to 1.30) | 19.9 |
| ≥30 | 28 | 114 | 0.89 (0.55 to 1.44) | 12.4 | 44 | 0.79 (0.46 to 1.36) | 0.0 |
| Planned pregnancy | |||||||
| Yes | 312 | 1051 | 1.00 | 579 | 1.00 | ||
| No | 17 | 285 | 4.20 (2.47 to 7.12) | 5.0 | 87 | 2.66 (1.52 to 4.65) | 0.0 |
| Parity | |||||||
| 0 | 209 | 744 | 1.00 | 369 | 1.00 | ||
| ≥1 | 120 | 592 | 1.44 (1.08 to 1.91) | 0.0 | 297 | 1.33 (0.98 to 1.80) | 0.0 |
| Previous abortions | |||||||
| No | 231 | 1047 | 1.00 | 504 | 1.00 | ||
| Yes | 98 | 289 | 0.58 (0.43 to 0.77) | 45.5 | 162 | 0.68 (0.50 to 0.94) | 42.0 |
| Private gynaecologist† | |||||||
| No | 189 | 923 | 1.00 | 423 | 1.00 | ||
| Yes | 140 | 413 | 0.78 (0.52 to 1.17) | 53.0 | 243 | 0.88 (0.42 to 1.88) | 84.2§ |
*Cohort-specific multinomial logistic models were combined using meta-analysis, the models were adjusted by all variables in the table.
†During the periconceptional stage from the preconception to the third month.
‡We used the results from fixed effect meta-analysis model when I2 was <50% and from the random effects meta-analysis model when I2 was >50%.
§P Cochran <0.05 from test of heterogeneity.
BMI, body mass index; RRR, relative risk ratio.