Table 1.
Participant characteristics and determinants of interest in the OaK Birth Cohort (n 7587), 2002–2009
| Variable | Frequency | |
|---|---|---|
| n | % | |
| Demographic characteristics | ||
| Age (years) | ||
| Mean | 30·3 | |
| sd | 5·06 | |
| Race (missing/unknown, n 415, 5·5 %) | ||
| African | 152 | 2·12 |
| Middle Eastern | 224 | 3·12 |
| Asian | 422 | 5·88 |
| Caucasian | 6250 | 87·1 |
| Other | 124 | 1·72 |
| College/university completed (missing, n 7, 0·09 %) | ||
| Yes | 5711 | 75·3 |
| No | 1869 | 24·6 |
| Household income in CAD (missing, n 485, 6·4 %) | ||
| <$50 000 | 1603 | 22·6 |
| $50 000–<80 000 | 5499 | 77·4 |
| Health indicators | ||
| BMI (missing, n 136, 1·8 %) | ||
| Mean | 24·9 | |
| sd | 5·49 | |
| Diabetes (missing, n 61, 0·80 %) | ||
| Yes | 115 | 1·53 |
| No | 7411 | 98·5 |
| Chronic hypertension (missing, n 64, 0·84 %) | ||
| Yes | 91 | 1·21 |
| No | 7432 | 98·8 |
| Pregnancy characteristics | ||
| Nulliparous (missing, n 738, 9·7 %) | ||
| Yes | 3059 | 44·7 |
| No | 3790 | 55·3 |
| Smoking during pregnancy (missing, n 26, 0·34 %) | ||
| No | 6714 | 88·8 |
| Second-hand exposure | 148 | 1·96 |
| Medium/light smoker (<10 cigarettes per day) | 449 | 5·93 |
| Heavy smoker (≥10 cigarettes per day) | 250 | 3·31 |
| Hormonal birth control prior to conception (missing, n 45, 0·59 %) | ||
| Yes | 2749 | 36·6 |
| No | 4783 | 63·4 |
| History of a placenta-mediated complication (pre-eclampsia, placental abruption, SGA, pregnancy loss) (missing, n 4, 0·053 %) | ||
| Yes | 794 | 10·5 |
| No | 6789 | 89·5 |
| Any folic acid supplementation (folic acid alone or from prenatal vitamin or from multivitamins) (missing, n 1, 0·01 %) | ||
| Yes | 7184 | 94·7 |
| No | 402 | 5·30 |
| Folic acid dose (mg) (missing, n 242, 3·19 %) | ||
| 0 | 402 | 5·47 |
| >0 and ≤1 | 5876 | 80·0 |
| >1 | 1067 | 14·5 |
| Homocysteine metabolism | ||
| Gestational age at bloodwork (weeks) | ||
| Mean | 13·7 | |
| sd | 2·09 | |
| Homocysteine (µmol/l) (missing, n 87, 1·1 %) | ||
| Mean | 4·8 | |
| sd | 1·3 | |
| Range | 1–34 | |
| Serum folate (nmol/l) (missing, n 987, 13·0 %) | ||
| Median | 37·4 | |
| IQR | 30·6–45·1 | |
| Range | 3·70–79·6 | |
| MTHFR genotype* | n 4006 | |
| CC (wild-type) | 1768 | 44·1 |
| CT (heterozygous) | 1760 | 43·9 |
| TT (homozygous) | 478 | 11·9 |
*
Measured in a subset of participants (n 4006).