Table 2.
Relationship between multivitamin supplement intake and preterm birth (PTB) among predominantly urban, low-income, minority mother–infant dyads (n 7576) enrolled in the Boston Birth Cohort, USA, from 1998 to 2014
| Period | Term (n 5507) | PTB (n 2069) | Unadjusted | Adjusted OR* | ||||
|---|---|---|---|---|---|---|---|---|
| ncases | % | ncases | % | OR | 95 % CI | OR | 95 % CI | |
| Multivitamin supplement intake in pregnancy (first to third trimester) | ||||||||
| Continuous (index)† | n/a | n/a | n/a | n/a | 0·97 | 0·96, 0·98 | 0·98 | 0·97, 0·99 |
| Categorical | ||||||||
| None (ref.) | 436 | 7·9 | 219 | 10·6 | 1·00 | n/a | 1·00 | n/a |
| 1–2 times/week | 933 | 16·9 | 406 | 19·6 | 0·87 | 0·71, 1·06 | 0·91 | 0·74, 1·12 |
| 3–5 times/week | 1373 | 24·9 | 476 | 23·0 | 0·69 | 0·57, 0·84 | 0·78 | 0·64, 0·96 |
| >5 times/week | 2765 | 50·2 | 968 | 46·8 | 0·70 | 0·58, 0·83 | 0·77 | 0·64, 0·93 |
| Multivitamin supplement intake in specific time periods | ||||||||
| Preconception | ||||||||
| None (ref.) | 5137 | 93·3 | 1940 | 93·8 | 1·00 | n/a | 1·00 | n/a |
| Any | 370 | 6·7 | 129 | 6·2 | 0·92 | 0·75, 1·14 | 0·90 | 0·72, 1·12 |
| First trimester | ||||||||
| None (ref.) | 914 | 16·6 | 402 | 19·4 | 1·00 | n/a | 1·00 | n/a |
| 1–2 times/week | 204 | 3·7 | 97 | 4·7 | 1·08 | 0·83, 1·41 | 1·08 | 0·82, 1·43 |
| 3–5 times/week | 1582 | 26·9 | 539 | 26·1 | 0·83 | 0·71, 0·96 | 0·90 | 0·76, 1·06 |
| >5 times/week | 2907 | 52·8 | 1031 | 49·8 | 0·81 | 0·70, 0·92 | 0·85 | 0·73, 0·98 |
| Second trimester | ||||||||
| None (ref.) | 642 | 11·7 | 290 | 14·0 | 1·00 | n/a | 1·00 | n/a |
| 1–2 times/week | 220 | 4·0 | 108 | 5·2 | 1·09 | 0·83, 1·42 | 1·19 | 0·90, 1·57 |
| 3–5 times/week | 1558 | 28·3 | 570 | 27·6 | 0·81 | 0·68, 0·96 | 0·92 | 0·77, 1·10 |
| >5 times/week | 3087 | 56·1 | 1101 | 53·2 | 0·79 | 0·68, 0·92 | 0·86 | 0·73, 1·02 |
| Third trimester | ||||||||
| None (ref.) | 655 | 11·9 | 345 | 16·8 | 1·00 | n/a | 1·00 | n/a |
| 1–2 times/week | 255 | 4·6 | 99 | 4·8 | 0·74 | 0·56, 0·96 | 0·80 | 0·61, 1·06 |
| 3–5 times/week | 1558 | 28·3 | 543 | 26·2 | 0·66 | 0·56, 0·78 | 0·75 | 0·63, 0·90 |
| >5 times/week | 3039 | 55·2 | 1082 | 52·3 | 0·68 | 0·58, 0·78 | 0·75 | 0·64, 0·87 |
ref., reference category; n/a, not applicable.
*
Adjusted for maternal race, age, nativity, education, marital status, receipt of public assistance, parity, cigarette use, alcohol use, stress, pre-eclampsia disorders, intra-uterine infection/inflammation and diabetes mellitus.
†
Composite measure of supplement intake from first to third trimester.