Table 2.
Baseline age-adjusted characteristics of participants in NHS II according to servings of maternal milk intake*
| NHS II
|
||||||
|---|---|---|---|---|---|---|
| Mothers’ milk intake (glasses) † | ||||||
| Characteristics | ≤3/mo | 1–4/wk | 5–6/wk | 1/day | 2–3/day | 4+/day |
| Number of nurses (%) | 5243 (14.8) | 4361 (12.3) | 22001 (5.7) | 9748 (27.6) | 12716 (36.0) | 1303 (3.7) |
|
| ||||||
| Nurses’ characteristics | ||||||
| Nurses age in ’89, mean | 34.4 | 34.0 | 34.1 | 34.3 | 34.2 | 34.0 |
| Ever Smoker in ’89, % | 32.4 | 32.2 | 32.6 | 31.7 | 31.3 | 29.4 |
| Smoking status ’89, % | ||||||
| Never | 67.5 | 67.7 | 67.3 | 68.2 | 68.6 | 70.5 |
| Past | 20.1 | 21.3 | 21.6 | 20.8 | 21.4 | 19.8 |
| Current | 12.3 | 10.8 | 10.9 | 10.9 | 9.9 | 9.5 |
| Tier of birth, % | ||||||
| North | 28.2 | 30.2 | 29.3 | 30.8 | 34.7 | 40.4 |
| Middle | 49.3 | 47.7 | 48.1 | 46.9 | 45.2 | 39.9 |
| South | 12.0 | 13.0 | 14.3 | 13.2 | 11.3 | 10.3 |
| Ethnicity, % | ||||||
| Southern European | 16.0 | 15.4 | 13.9 | 13.6 | 11.4 | 11.5 |
| Scandinavian | 3.4 | 3.8 | 4.0 | 4.6 | 5.7 | 5.9 |
| Other Caucasian | 72.6 | 73.7 | 76.9 | 75.7 | 77.4 | 76.8 |
| Other | 8.0 | 7.2 | 5.1 | 6.1 | 5.5 | 5.8 |
| Nurses’ baseline diet, mean | ||||||
| Whole milk, servings/d | 0.06 | 0.07 | 0.06 | 0.07 | 0.07 | 0.09 |
| Skim milk, servings/d | 0.87 | 0.97 | 1.00 | 1.02 | 1.24 | 1.37 |
| Total milk, servings/d | 0.93 | 1.04 | 1.06 | 1.09 | 1.31 | 1.46 |
| Total Vitamin D, IU | 371.0 | 381.1 | 390.9 | 390.7 | 414.6 | 428.8 |
| Vitamin D w/o supp., IU | 236.6 | 247.2 | 248.9 | 253.8 | 271.9 | 284.8 |
| Preschool vitamin intake, % | 62.9 | 66.2 | 69.6 | 68.1 | 71.0 | 73.1 |
| Preschool codliver oil intake, % | 12.0 | 10.9 | 10.4 | 12.1 | 11.6 | 15.0 |
| Mother’s characteristics | ||||||
| Mother’s age at birth, mean | 26.2 | 26.2 | 26.1 | 26.5 | 26.3 | 26.2 |
| Prenatal vitamin users, % | 61.2 | 66.7 | 69.9 | 68.3 | 73.5 | 74.5 |
| Smoke during pregnancy,% | 29.4 | 28.8 | 27.6 | 25.2 | 24.7 | 22.0 |
| Alcohol use (pregnancy),% | 30.0 | 34.0 | 34.1 | 31.2 | 31.7 | 24.5 |
| Breast Feeding, % | 37.4 | 41.6 | 43.1 | 45.0 | 50.6 | 55.9 |
| Own Home | 52.9 | 52.8 | 53.2 | 51.3 | 51.6 | 51.4 |
| Mothers’ BMI, mean | 21.3 | 21.4 | 21.3 | 21.4 | 21.14 | 21.01 |
| Mother’s leisure physical activity, % | ||||||
| Highly active | 9.9 | 8.0 | 8.5 | 9.0 | 10.8 | 18.3 |
| Somewhat active | 17.5 | 19.1 | 20.4 | 18.8 | 21.6 | 22.5 |
| Active | 35.6 | 38.9 | 40.6 | 41.9 | 40.4 | 36.5 |
| Mostly inactive | 21.6 | 22.3 | 21.8 | 20.6 | 18.5 | 15.2 |
| Inactive | 14.9 | 11.5 | 8.3 | 9.2 | 8.3 | 7.1 |
| Mother’s education, % | ||||||
| Less than high school | 19 | 15 | 12 | 13 | 11 | 12 |
| High School | 53 | 52 | 51 | 51 | 47 | 44 |
| College | 28 | 32 | 37 | 35 | 42 | 44 |
| Father’s education, % | ||||||
| Less than high school | 21.7 | 19.5 | 19.5 | 17.8 | 15.2 | 16.3 |
| High School | 39.7 | 37.3 | 36.3 | 37.6 | 35.4 | 31.6 |
| College | 33.4 | 38.4 | 40.7 | 40.4 | 45.7 | 48.3 |
| Father high paying job, % | 22.7 | 25.6 | 27.6 | 28.0 | 31.2 | 33.3 |
*
Each category is directly standardized to the baseline age distribution of the cohort
†
In the Nurses Mother’s Study, 421 women were missing “mothers’ milk intake”