Table 2.
Geometric mean concentrations of serum and RBC folate by characteristics of participants: pregnant women (n 869) recruited between 12 and 20 weeks of gestation, Ottawa and Kingston (OaK) Birth Cohort study, April 2008–April 2009
| Serum folate (nmol/l) | RBC folate (nmol/l) | |||||||
|---|---|---|---|---|---|---|---|---|
| Unadjusted geometric mean | 95 % CI | Adjusted geometric mean‡ | 95 % CI | Unadjusted geometric mean | 95 % CI | Adjusted geometric mean‡ | 95 % CI | |
| Overall | 45·7 | 44·1, 47·4 | – | – | 1549 | 1521, 1577 | – | – |
| BMI (kg/m2) | ||||||||
| <25·0 | 47·5 | 45·2, 50·0 | 47·4 | 45·2, 49·6 | 1500 | 1460, 1541 | 1503 | 1467, 1540 |
| 25·0–29·9 | 45·4 | 42·6, 48·3 | 45·0 | 42·2, 48·0 | 1549 | 1494, 1606 | 1532 | 1481, 1585 |
| ≥30·0 | 40·3 | 37·5, 43·3 | 41·0* | 38·3, 44·0 | 1591 | 1527, 1657 | 1604* | 1546, 1663 |
| MTHFR 677C→T genotype | ||||||||
| CC | 46·4 | 44·0, 49·0 | 46·6 | 44·3, 49·0 | 1552 | 1504, 1602 | 1553 | 1513, 1594 |
| CT | 44·8 | 42·6, 47·0 | 44·3 | 42·2, 46·5 | 1471 | 1432, 1512 | 1473* | 1436, 1510 |
| TT | 43·0 | 39·2, 47·3 | 44·1 | 40·1, 48·5 | 1712* | 1629, 1799 | 1704*,† | 1622, 1790 |
| Folic acid supplement | ||||||||
| Non-users | 24·1 | 21·8, 26·6 | 25·8 | 21·9, 30·5 | 1275 | 1155, 1409 | 1306 | 1197, 1426 |
| ≤1 mg/d | 44·2* | 42·9, 45·7 | 44·1* | 42·6, 45·8 | 1512* | 1485, 1540 | 1514* | 1517, 1613 |
| >1 mg/d | 61·4*,† | 53·7, 70·3 | 61·0*,† | 55·9, 66·5 | 1743*,† | 1666, 1824 | 1722*,† | 1645, 1803 |
| Age (years) | ||||||||
| ≤29 | 42·3 | 40·2, 44·4 | 43·4 | 41·3, 45·6 | 1430 | 1392, 1469 | 1470 | 1433, 1509 |
| 30–34 | 47·5* | 44·8, 50·3 | 46·5 | 43·9, 49·3 | 1603* | 1560, 1647 | 1564* | 1517, 1613 |
| ≥35 | 49·7* | 45·8, 53·9 | 48·0 | 44·4, 51·9 | 1700* | 1633, 1771 | 1650* | 1583, 1720 |
| GA at recruitment (week) | ||||||||
| 12 | 45·9 | 44·1, 47·8 | 45·7 | 43·9, 47·5 | 1512 | 1478, 1546 | 1512 | 1481, 1544 |
| 13–15 | 44·9 | 41·8, 48·3 | 45·7 | 42·9, 48·6 | 1554 | 1498, 1611 | 1555 | 1504, 1607 |
| 16–20 | 39·2* | 35·0, 43·8 | 38·0* | 33·0, 43·8 | 1707* | 1581, 1843 | 1693* | 1571, 1825 |
| Maternal education | ||||||||
| High school and below | 40·2 | 36·9, 43·7 | 42·1 | 38·6, 45·9 | 1327 | 1269, 1388 | 1408 | 1345, 1473 |
| College/university not completed | 42·6 | 38·1, 47·7 | 43·2 | 38·6, 48·4 | 1502* | 1403, 1607 | 1496 | 1410, 1589 |
| College/university completed | 47·1* | 45·2, 49·0 | 46·4 | 44·5, 48·4 | 1599* | 1563, 1635 | 1574* | 1540, 1608 |
| Race | ||||||||
| Caucasian | 44·8 | 43·3, 46·5 | 44·9 | 43·4, 46·5 | 1531 | 1503, 1558 | 1532 | 1504, 1560 |
| Other races | 49·9 | 43·8, 56·9 | 49·0 | 43·6, 54·9 | 1559 | 1456, 1668 | 1545 | 1454, 1642 |
| Household annual income ($CAN) | ||||||||
| ≤49 999 | 40·7 | 37·9, 43·8 | 43·2 | 40·1, 46·6 | 1375 | 1320, 1432 | 1490 | 1432, 1550 |
| 50 000–79 999 | 46·4* | 43·7, 49·2 | 46·2 | 43·5, 49·0 | 1576* | 1527, 1626 | 1544 | 1496, 1593 |
| ≥80 000 | 47·6* | 44·9, 50·5 | 45·5 | 42·9, 48·4 | 1615* | 1571, 1659 | 1540 | 1492, 1590 |
| Declined | 48·9 | 41·9, 57·0 | 49·3 | 42·7, 56·9 | 1645* | 1537, 1760 | 1656 | 1535, 1786 |
| Smoking | ||||||||
| No | 45·5 | 43·9, 47·1 | 45·1 | 43·5, 46·7 | 1569 | 1541, 1597 | 1553 | 1524, 1583 |
| Yes | 44·1 | 39·9, 48·7 | 46·2 | 42·3, 50·6 | 1352* | 1280, 1427 | 1426* | 1360, 1495 |
RBC, red blood cell; MTHFR, methylenetetrahyrofolate reductase gene; GA, gestational age.
*
Significantly different from the first category of the listed variables (P < 0·05).
†
Significantly different from the second category of the listed variables (P < 0·05).
‡
Adjusted for all other variables listed.