Pooled RRR* and 95% CI of folic acid supplements doses in the second 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 second period† | ||||||
|---|---|---|---|---|---|---|---|
| 400–999 (mean=511.7) | <400, included non use (mean=59.1) | ≥1000 (mean=4095.2) | |||||
| 657 (28%) | 1275 (55%) | 394 (17%) | |||||
| n | n | RRR* (95% CI) | I2 (%)‡ | n | RRR* (95% CI) | I2 (%)‡ | |
| Maternal age (years) | |||||||
| ≤30 | 343 | 653 | 1.00 | 164 | 1.00 | ||
| >30 | 314 | 622 | 1.05 (0.61 to 1.82) | 77.2§ | 230 | 1.54 (0.92 to 2.59) | 61.8§ |
| Maternal education | |||||||
| Primary school or less | 194 | 284 | 1.00 | 82 | 1.00 | ||
| Secondary school | 274 | 523 | 1.29 (0.97 to 1.72) | 0.0 | 168 | 1.26 (0.88 to 1.80) | 0.0 |
| University studies | 189 | 468 | 1.30 (0.92 to 1.85) | 0.0 | 144 | 1.20 (0.54 to 2.66) | 65.4§ |
| Paternal education | |||||||
| Primary school or less | 254 | 441 | 1.00 | 133 | 1.00 | ||
| Secondary school | 282 | 568 | 0.89 (0.69 to 1.15) | 0.0 | 182 | 0.94 (0.68 to 1.29) | 0.0 |
| University studies | 121 | 266 | 0.78 (0.54 to 1.12) | 0.0 | 79 | 0.80 (0.52 to 1.22) | 25.3 |
| Tobacco smoking† | |||||||
| No | 512 | 1088 | 1.00 | 332 | 1.00 | ||
| Yes | 145 | 187 | 0.70 (0.42 to 1.18) | 61.7¶ | 62 | 0.67 (0.47 to 0.96) | 8.1 |
| Alcohol consumption† | |||||||
| No | 426 | 767 | 1.00 | 252 | 1.00 | ||
| Yes | 231 | 508 | 1.01 (0.80, 1.28) | 0.0 | 142 | 1.09 (0.82 to 1.45) | 0.0 |
| Pre-pregnancy BMI | |||||||
| <25 | 456 | 970 | 1.00 | 281 | 1.00 | ||
| 25–29.9 | 138 | 217 | 0.82 (0.62 to 1.09) | 0.0 | 80 | 0.89 (0.63 to 1.25) | 0.0 |
| ≥30 | 63 | 88 | 0.70 (0.47 to 1.06) | 11.5 | 33 | 0.87 (0.53 to 1.43) | 0.0 |
| Planned pregnancy | |||||||
| Yes | 531 | 1073 | 1.00 | 336 | 1.00 | ||
| No | 126 | 202 | 1.05 (0.78 to 1.41) | 0.0 | 58 | 0.90 (0.61 to 1.32) | 0.0 |
| Parity | |||||||
| 0 | 381 | 717 | 1.00 | 223 | 1.00 | ||
| ≥1 | 276 | 558 | 1.08 (0.85 to 1.38) | 35.5 | 171 | 0.99 (0.74 to 1.33) | 76.3§ |
| Previous abortions | |||||||
| No | 504 | 974 | 1.00 | 301 | 1.00 | ||
| Yes | 153 | 301 | 1.07 (0.82 to 1.41) | 7.8 | 93 | 0.95 (0.69 to 1.31) | 10.9 |
| Private gynaecologist¶ | |||||||
| No | 404 | 880 | 1.00 | 245 | 1.00 | ||
| Yes | 253 | 395 | 0.88 (0.60 to 1.27) | 54.9 | 149 | 0.79 (0.28 to 2.21) | 91.3§ |
*Cohort-specific multinomial logistic models were combined using meta-analysis, the models were adjusted by all variables in the table.
†Second period covers the months from the fourth to the seventh month of pregnancy.
‡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.
¶During the periconceptional stage (first period) from the preconception to the third month.
BMI, body mass index; RRR, relative risk ratio.