Participants were 253 mothers who completed a survey on the WWW; of this number 80 mothers were currently breast-feeding, 42 only bottle-fed their child, 131 mothers had already weaned their child. These mothers reported any treatment for a medical disorder during the previous month and whether that condition started before the last childbirth (pre-partum onset) or had started after the last childbirth (post-partum onset).

Results showed that while rates of pre-partum onset of psychological problems were similar among the breast-feeding, bottle-feeding, and weaned mothers, the rates of post-partum onset disorders were significantly different: 2.4% among the currently breast-feeding mothers, 2.5% among the bottle-feeding group, and 19.8% among the weaned mothers. A number of factors were controlled-- marital, work, and socioeconomic status; number of children; ages of mother and child. The results also indicated, however, that the more a woman breast-fed before she weaned, the less likely she developed a psychological disorder after she weaned. Therefore, the results support the notion that early weaning, not weaning itself, may be detrimental to the psychological health of the mother