Michigan women who expressed breast milk during the first 3 weeks were twice as likely to stop breastfeeding as those who did not pump. During the same period, Michigan women who used a bottle for some feedings were 9 times more likely to wean than nonbottle users. Respondents in Nebraska showed similar nonsignificant trends in the first 3 weeks. By contrast, during weeks 4 through 12, both Nebraska and Michigan women who pumped were about 75% less likely to wean, while women who used a bottle for some feedings were 98% less likely to stop breastfeeding.
Breast milk expression increased gradually over time, from 30% of women pumping an average of 3 times per day in the first 3 weeks to 45% of women pumping 5 times per day in the last 3 weeks. To determine if pumping and bottle-feeding had an effect independent of pain or mastitis on weaning in the first 3 weeks, we performed additional analyses controlling for pain, cracks and sores, and mastitis in the same week. The results were similar to those presented in Table 2. Michigan women who pumped were 3 times more likely to wean than those who did not pump (hazard ratio [HR] = 3.0, 95% confidence interval [CI], 1.3 - 6.7), while for Nebraska women there was no association between pumping and weaning (HR = 0.6, 95% CI, 0.3 - 1.5). Bottle-feeding was again significantly associated with weaning in weeks 1 through 3 for Michigan women (HR = 10.9, 95% CI, 4.5 - 26.7) and not associated in Nebraskans (HR = 0.8, 95% CI, 0.4 - 2.0).
Duration and frequency of feedings were investigated as weaning risk factors. There appeared to be a threshold for both variables during the first 3 weeks in Michigan women. Michigan women who breastfed less than 10 minutes per feeding were nearly 5 times more likely to stop breastfeeding than women who breastfed longer. Michigan women who breastfed 6 or fewer times per day were 8 times more likely to stop than those who breastfed more often. Results for Nebraska women fell in the same direction but were not statistically significant.
TABLE 2
Relationships of clinical and behavioral factors to breastfeeding cessation in the same week, adjusted for mother’s age, education, and previous breastfeeding experience
| Variable | Week | Michigan women HR (95% CI) | Nebraska women HR (95% CI) |
|---|---|---|---|
| Mastitis | 1 - 3 | 5.7 (1.3 - 25.9) | ‡ |
| 4 - 12 | ‡ | 2.1 (0.3 - 17.4) | |
| Engorgement | 1 - 3 | 0.6 (0.2 - 1.5) | 0.8 (0.3 - 2.1) |
| 4 - 12 | ‡ | 3.2 (0.6 - 15.8) | |
| Nipple sores/cracks | 1 - 3 | 1.1 (0.4 - 2.6) | 0.9 (0.4 - 2.3) |
| 4 - 12 | 2.6 (0.8 - 8.5) | 2.9 (0.8 - 10.7) | |
| Any pain † | 1 - 3 | 14.7 (6.8 - 32.0)§ | 9.1 (3.9 - 21.2)† |
| 4 - 12 | 0.3 (0.1 - 0.7) | 0.2 (0.1 - 0.5)† | |
| Days with pain* | 1 - 3 | 1.1 (1.0 - 1.2) | 1.3 (1.0 - 1.5) |
| 4 - 12 | 1.1 (1.0 - 1.2) | 1.1 (1.0 - 1.2) | |
| Returned to work | 1 - 3 | 0.4 (0.1 - 3.0) | ‡ |
| 4 - 12 | 2.1 (1.1 - 4.0) | 0.8 (0.4 - 1.7) | |
| Depressed | 1 - 3 | 0.9 (0.3 - 3.0) | 1.0 (0.4 - 2.6) |
| 4 - 12 | 0.9 (0.4 - 2.2) | 1.3 (0.6 - 2.7) | |
| Daily sleep hours | 1 - 3 | 0.9 (0.7 - 1.1) | 0.9 (0.8 - 1.2) |
| 4 - 12 | 0.7 (0.5 - 0.9) | 1.2 (1.0 - 1.5) | |
| Outside household help | 1 - 3 | 2.0 (0.8 - 4.8) | 0.9 (0.4 - 2.1) |
| 4 - 12 | 0.7 (0.3 - 2.6) | 0.7 (0.2 - 2.1) | |
| Pumping | 1 - 3 | 2.2 (1.1 - 4.6) | 1.3 (0.6 - 2.5) |
| 4 - 12 | 0.2 (0.1 - 0.5)§ | 0.3 (0.1 - 0.5) § | |
| Bottle feeding | 1 - 3 | 9.5 (4.3 - 21.0) § | 1.8 (0.9 - 3.5) |
| 4 - 12 | 0.03 (0.003 - 0.2) § | 0.02 (0.004 - 0.1) § | |
| Minutes per feeding | 1 - 3 | 1.0 (0.9, 1.0) | 1.1 (1.0, 1.1) |
| Less than 10 minutes per feeding | 1 - 3 | 4.8 (1.7, 13.4) | 2.2 (0.6, 8.1) |
| Feedings per day | 1 - 3 | 0.7 (0.6, 0.8) § | 0.9 (0.8, 1.1) |
| Less than 7 feedings/day | 1 - 3 | 8.1 (3.4, 19.2) § | 1.8 (0.7, 4.6) |
| NOTE: Bold numbers significant at P = .05 or less; those marked with § are significant at P = .001 or less. | |||
| HR denotes hazard ratio; CI, confidence interval. | |||
| *Subjects answered affirmatively to any of the following types of pain: pain when latching on, pain while nursing, pain when not nursing. | |||
| † Measured in 3-week periods. | |||
| ‡ Indicates there were too few observations to provide meaningful results; for example, there were no Nebraska women who had mastitis and stopped breastfeeding in the same week during weeks 1-3. | |||
Subjective factors
At each interview, women who had stopped breastfeeding in the previous 3 weeks were asked why they had made that decision. Most women (75%) provided only one reason. At the first interview, insufficient milk supply (37.3%) and breast pain or mastitis (32.9%) were the most common reasons for termination (Table 3). Insufficient milk supply was the reason most often given (35.0%) during weeks 4 through 6. At both weeks 9 and 12, return to work was the reason given most often (53.1% and 58.3%, respectively).