Table 2.
Prevalence of early interruption of breastfeeding (≤ 1 month) according to season of birth, stratified by maternal education; Pelotas birth cohort studies
| 1982 Birth Cohort |
1993 Birth Cohort |
2004 Birth Cohort |
|||||||
|---|---|---|---|---|---|---|---|---|---|
| Maternal education |
Maternal education |
Maternal education |
|||||||
| 0–4 years | >4 years | 0–4 years | >4 years | 0–4 years | >4 years | ||||
| All % | n (%) | n (%) | All % | n (%) | n (%) | All % | n (%) | n (%) | |
| Any breastfeeding ≤ 1 month | |||||||||
| Trimester of birtha | P = 0.007 | P < 0.001 | P = 0.4 | P = 0.04 | P = 0.1 | P = 0.2 | P = 0.2 | P = 0.5 | P = 0.2 |
| Jan–Mar | 30.5 | 413 (28.3) | 878 (31.4) | 19.1 | 83 (20.5) | 251 (18.7) | 14.1 | 167 (17.4) | 856 (13.6) |
| Apr–Jun | 34.9 | 447 (40.9) | 895 (31.8) | 25.1 | 91 (29.1) | 260 (23.7) | 16.5 | 176 (19.3) | 897 (15.9) |
| Jul–Sep | 32.6 | 451 (33.0) | 945 (32.5) | 21.0 | 100 (26.0) | 243 (18.9) | 15.3 | 158 (13.9) | 872 (15.7) |
| Oct–Dec | 29.0 | 417 (29.5) | 881 (28.8) | 16.4 | 103 (15.5) | 255 (16.9) | 13.1 | 122 (14.8) | 804 (13.1) |
| Temperature 1st monthb,c | P < 0.001 | P < 0.001 | P = 0.003 | P = 0.08 | P = 0.06 | P = 0.2 | P = 0.1 | P = 0.04 | P = 0.5 |
| Coldest quintile | 38.1 | 343 (43.4) | 725 (35.6) | 25.5 | 74 (28.1) | 186 (24.5) | 16.1 | 117 (24.8) | 707 (14.9) |
| Quintiles 2–4 | 31.1 | 1041 (31.9) | 2153 (30.7) | 18.8 | 230 (21.0) | 601 (17.9) | 14.7 | 391 (14.6) | 2039 (14.9) |
| Hottest quintile | 27.8 | 344 (26.5) | 721 (28.3) | 19.1 | 73 (16.8) | 223 (19.9) | 13.7 | 115 (14.8) | 683 (13.6) |
| SII (95% CI)d | −21.1 (−32.7, −9.5) | −9.1 (−13.9, −4.4) | −14.1 (−19.9, −8.6) | −5.0 (−21.5, 11.4) | −12.4 (−32.2, 7.4) | −1.6 (−4.1, 0.9) | |||
| Predominant breastfeeding ≤ 1 month | |||||||||
| Trimester of birtha | P = 0.1 | P = 0.003 | P = 0.7 | P = 0.2 | P = 0.1 | P = 0.3 | P = 0.6 | P = 0.6 | P = 0.5 |
| Jan–Mar | 37.5 | 405 (37.8) | 864 (37.3) | 35.6 | 84 (34.4) | 267 (36.0) | 26.1 | 161 (31.7) | 837 (25.1) |
| Apr–Jun | 41.3 | 430 (49.1) | 866 (37.3) | 42.8 | 92 (51.6) | 265 (39.7) | 28.2 | 172 (31.4) | 875 (27.5) |
| Jul–Sep | 39.7 | 431 (41.1) | 915 (39.1) | 36.6 | 104 (44.9) | 250 (33.2) | 26.5 | 154 (25.3) | 846 (26.8) |
| Oct–Dec | 37.1 | 391 (38.1) | 836 (36.7) | 39.3 | 104 (37.2) | 262 (40.2) | 25.7 | 122 (31.2) | 788 (24.9) |
| Temperature 1st monthb,c | P < 0.001 | P < 0.001 | P = 0.02 | P = 0.4 | P = 0.2 | P = 0.8 | P = 0.7 | P = 0.1 | P = 0.8 |
| Coldest quintile | 44.7 | 327 (51.1) | 698 (41.8) | 41.4 | 76 (47.0) | 187 (38.7) | 27 | 114 (38.6) | 686 (25.2) |
| Quintiles 2–4 | 38.0 | 1001 (40.5) | 2080 (36.8) | 38.2 | 234 (39.5) | 619 (37.7) | 26.7 | 384 (27.3) | 1994 (26.5) |
| Hottest quintile | 36.0 | 329 (35.9) | 703 (36.0) | 37.6 | 75 (37.1) | 238 (37.8) | 26.2 | 111 (29.7) | 666 (25.8) |
| SII (95% CI)d | −18.9 (−30.4, −7.5) | −7.2 (−15.2, 0.7) | −12.3 (−22.0, −2.7) | −1.0 (−3.1, 1.1) | −11.1 (−37.2, 15.0) | −0.8 (−4.6, 3.0) | |||
aχ2 test for heterogeneity.
bχ2 test for trend.
cMean environmental temperature in the first month of life.
dTemperature-based slope indices of inequality.