TABLE 1.
Background characteristics of the 49,669 Norwegian women in the MoBa sample by breastfeeding pattern1
| Total sample, % | Initiated breastfeeding, % | Sustained full breastfeeding for 4 mo postpartum,2 % | Sustained any breastfeeding for 4 mo postpartum,2 % | Sustained full breastfeeding for 6 mo postpartum,2 % | Sustained any breastfeeding for 6 mo postpartum,2 % | |
| All women | 100 | 99.3 | 59.1 | 88.1 | 13.7 | 80.6 |
| Maternal age (y) | ||||||
| ≤19 | 0.9 | 98.0* | 32.3* | 58.5* | 3.8* | 49.4* |
| 20–24 | 10.6 | 99.3 | 48.3 | 77.8 | 7.1 | 66.2 |
| 25–29 | 34.5 | 99.4 | 58.4 | 88.1 | 11.3 | 80.3 |
| 30–34 | 37.5 | 99.3 | 61.8 | 90.8 | 15.6 | 84.4 |
| 35–39 | 14.5 | 99.1 | 63.0 | 90.4 | 18.8 | 83.6 |
| ≥40 | 2.0 | 98.6 | 61.1 | 88.1 | 19.8 | 81.8 |
| Parity | ||||||
| 0 | 54.0 | 99.3 | 53.4* | 86.8* | 11.0* | 79.2* |
| 1 | 29.3 | 99.2 | 64.3 | 89.2 | 14.6 | 81.3 |
| 2 | 13.1 | 99.1 | 68.6 | 90.8 | 19.1 | 84.5 |
| 3 | 2.8 | 99.3 | 68.9 | 89.0 | 25.2 | 81.9 |
| ≥4 | 0.8 | 99.0 | 65.2 | 86.6 | 24.2 | 78.1 |
| Maternal education (y) | ||||||
| <12 | 6.2 | 98.3* | 45.6* | 70.8* | 8.7* | 59.4* |
| 12 | 24.7 | 98.9 | 52.2 | 80.5 | 9.6 | 69.7 |
| 13–16 | 42.7 | 99.5 | 61.5 | 91.2 | 14.2 | 84.5 |
| ≥17 | 24.4 | 99.6 | 65.4 | 94.7 | 18.2 | 90.2 |
| Other and missing | 2.0 | 98.8 | 57.3 | 86.2 | 11.7 | 78.3 |
| Household income, NOK/y | ||||||
| Both incomes <300,000 | 29.5 | 99.1* | 55.6* | 83.8* | 11.5* | 75.1* |
| One income ≥300,000 | 41.8 | 99.3 | 59.7 | 88.5 | 14.0 | 80.8 |
| Both incomes ≥300,000 | 26.2 | 99.5 | 62.5 | 92.7 | 15.5 | 87.0 |
| Missing | 2.6 | 98.3 | 55.0 | 82.4 | 14.0 | 73.8 |
| Marital status | ||||||
| Married | 46.0 | 99.3** | 63.6* | 91.0* | 16.5* | 84.5* |
| Cohabitating | 50.2 | 99.3 | 56.0 | 86.2 | 11.4 | 77.9 |
| Single/widow | 2.2 | 98.6 | 45.0 | 75.3 | 9.8 | 66.2 |
| Other or not known | 1.5 | 98.9 | 48.7 | 80.1 | 9.4 | 71.6 |
| Prepregnancy BMI (kg/m2) | ||||||
| <18.5 | 3.0 | 99.0* | 57.8* | 85.1* | 14.2* | 77.0* |
| 18.5–24.9 | 65.9 | 99.6 | 62.9 | 90.6 | 14.8 | 83.8 |
| 25.0–29.9 | 21.8 | 98.8 | 54.4 | 85.7 | 11.6 | 77.4 |
| 30.0–34.9 | 6.8 | 98.7 | 45.4 | 77.9 | 10.3 | 68.4 |
| ≥35.0 | 2.4 | 97.4 | 37.8 | 71.3 | 8.9 | 58.7 |
| Pregnancy weight gain (kg) | ||||||
| <10 | 15.5 | 98.8* | 56.7* | 86.3* | 14.1* | 78.8* |
| 10–15 | 41.6 | 99.4 | 61.9 | 89.9 | 15.0 | 83.2 |
| 16–19 | 22.7 | 99.4 | 61.0 | 89.5 | 13.7 | 82.3 |
| ≥20 | 20.2 | 99.2 | 53.2 | 84.0 | 10.6 | 74.5 |
| Smoking in early pregnancy | ||||||
| None | 91.3 | 99.3* | 60.6* | 89.7* | 14.4* | 82.7* |
| Occasionally | 2.7 | 99.3 | 47.0 | 74.9 | 6.5 | 63.5 |
| Daily | 5.3 | 98.0 | 39.3 | 67.6 | 4.8 | 53.1 |
| Missing | 0.7 | 98.8 | 55.5 | 81.7 | 11.3 | 71.3 |
| Exercise in last 3 mo before pregnancy | ||||||
| None | 5.7 | 98.6* | 50.0* | 79.7* | 9.8* | 69.9* |
| Less than weekly | 13.8 | 99.0 | 55.3 | 84.7 | 11.7 | 75.8 |
| 1–2 times/wk | 28.6 | 99.4 | 59.8 | 88.6 | 13.5 | 81.3 |
| ≥3 times/wk | 48.6 | 99.4 | 61.2 | 90.1 | 14.8 | 83.3 |
| Missing | 3.2 | 98.3 | 54.8 | 81.3 | 12.6 | 72.0 |
| Exercise in early pregnancy | ||||||
| None | 14.0 | 98.8* | 52.7* | 82.6* | 10.8* | 73.3* |
| Less than weekly | 19.8 | 99.3 | 57.4 | 87.2 | 13.0 | 79.2 |
| 1–2 times/wk | 29.9 | 99.5 | 60.5 | 89.2 | 13.9 | 82.3 |
| ≥3 times/wk | 28.6 | 99.5 | 62.6 | 91.2 | 15.4 | 84.8 |
| Missing | 7.6 | 98.4 | 56.7 | 83.9 | 13.1 | 74.5 |
| Exercise in 6 mo postpartum | ||||||
| None | 8.9 | 98.6* | 52.1* | 82.1* | 11.5* | 73.2* |
| Less than weekly | 10.5 | 99.1 | 57.5 | 86.6 | 12.4 | 78.5 |
| 1–2 times/wk | 26.9 | 99.4 | 59.5 | 88.2 | 13.7 | 80.9 |
| ≥3 times/wk | 53.0 | 99.4 | 60.5 | 89.3 | 14.2 | 82.1 |
| Missing | 0.6 | 98.9 | 51.8 | 82.0 | 14.7 | 74.1 |
1
Categories differ from one another (chi-square test): *P < 0.001, **P < 0.05. MoBa, Norwegian Mother and Child Cohort Study; NOK, Norwegian crowns.
2
Among the 49,309 women who initiated breastfeeding.