Table 4.
Risk of Oral Cleftsa by Quartiles of Maternal Biomarkers of Folate-Dependent One-Carbon Metabolism and Interval between Birth of Index Child and Maternal Blood Specimen Collection
| Maternal biomarker (sample size) | Quartile | Adjustedb odds ratio and 95% confidence intervals by interval between birth of index child and collection of maternal blood specimen
|
||
|---|---|---|---|---|
| 12–36 months | >36–≤60 months | >60 months | ||
| Plasma folate (nmol/L; 347 cases, 468 controls) | Quartile 1 (≤36.7) | 1.0 (reference) | 1.0 (reference) | 1.0 (reference) |
| Quartile 2 (36.7–53.6) | 0.98 (0.52–1.83) | 0.63 (0.27–1.47) | 0.74 (0.37–1.48) | |
| Quartile 3 (53.7–74.0) | 1.19 (0.63–2.27) | 0.18 (0.07–0.51) | 0.36 (0.18–0.74) | |
| Quartile 4 (≥74.1) | 0.62 (0.34–1.16) | 0.15 (0.06–0.40) | 0.26 (0.12–0.57) | |
| p-trend | p = 0.18 | p < 0.001 | p ≪0.001 | |
| Erythrocyte folate (nmol/L; 345 cases, 465 controls) | Quartile 1 (≤1488) | 1.0 (reference) | 1.0 (reference) | 1.0 (reference) |
| Quartile 2 (1489–1878) | 1.48 (0.78–2.83) | 0.59 (0.26–1.33) | 0.54 (0.25–1.14) | |
| Quartile 3 (1879–2486) | 1.13 (0.60–2.14) | 0.62 (0.27–1.43) | 0.16 (0.07–0.37) | |
| Quartile 4 (≥2487) | 1.13 (0.59–2.17) | 0.21 (0.07–0.63) | 0.46 (0.23–0.93) | |
| p-trend | p = 0.97 | p = 0.01 | p = 0.004 | |
| Plasma pyridoxal-5′-phosphate (nmol/L; (347 cases, 468 controls) | Quartile 1 (< 26.0) | 1.0 (reference) | 1.0 (reference) | 1.0 (reference) |
| Quartile 2 (26.1–45.0) | 1.04 (0.55–1.97) | 0.89 (0.37–2.15) | 0.54 (0.27–1.08) | |
| Quartile 3 (45.1–78.0) | 1.27 (0.68–2.38) | 0.87 (0.37–2.01) | 0.49 (0.23–1.03) | |
| Quartile 4 (≥78.1) | 0.91 (0.49–1.71) | 0.61 (0.25–1.45) | 0.63 (0.30–1.25) | |
| p-trend | p = 0.90 | p = 0.29 | p = 0.14 | |
| Plasma homocysteine (μmol/L; 327 cases, 426 controls) | Quartile 1 (≤3.2) | 1.0 (reference) | 1.0 (reference) | 1.0 (reference) |
| Quartile 2 (3.21–4.0) | 1.08 (0.59–2.01) | 0.64 (0.26–1.55) | 1.35 (0.61–3.04) | |
| Quartile 3 (4.1–5.0) | 1.47 (0.79–2.73) | 0.47 (0.19–1.19) | 1.35 (0.62–2.95) | |
| Quartile 4 (≥5.1) | 0.89 (0.47–1.67) | 1.18 (0.48–2.88) | 2.23 (1.01–4.91) | |
| p-trend | p = 0.95 | p = 0.90 | p = 0.056 | |
a
Cases include all oral clefts with the exclusion of known genetic syndromes and chromosomal abnormalities.
b
Adjusted for maternal age, education, alcohol use, smoking, multivitamin use, and interval between delivery of the index child and maternal blood collection in logistic regression models.