To the best of our knowledge, this is the first study to report on the association between infant temperament and specific aspects of diet at age 18 months, and to examine drinks at night as a potential source of excess calories (25
). Maternal characteristics have been studied in past research (22
), but infants’ psychological traits have not hitherto been examined as potential influences on mothers’ food choices for their child. Consistent with our hypotheses, children who were described by their mothers as having distress-prone temperaments on one or both of the internalizing and externalizing dimensions were more likely to be fed sweet foods, sweet drinks, and caloric drinks at night. Internalizing was related to all three dietary variables. In addition, surgency/extraversion was related to feeding of drinks at night. Consistent with previous studies, maternal negative affect also predicted these potentially obesogenic dietary patterns. The associations between infant temperament and dietary patterns were independent of maternal years of education and maternal negative affectivity, infant weight-for-height and gender, and of sustained breastfeeding (which reduces the necessity to feed the infant other foods and drinks (18
These cross-sectional findings are open to various interpretations. Mothers may be responding to their infants’ anxiousness, reactivity, and difficulty sleeping by attempting to comfort and calm them with sweet foods and drinks. This interpretation is consistent with a transactional view in which, as a result of their temperaments, infants effectively manipulate their environment by evoking a particular pattern of behavior in another individual (35
). Because sweet flavors are particularly soothing, it may be that mothers are moved to provide sweet foods and drinks because they are more likely to soothe the distress-prone infant than other foods. Mothers who are higher in negative affectivity may also be more upset by their infant’s distress and hence even more likely to use sweet foods and drinks. We examined this possibility by including the interaction between mothers’ negative affectivity and each of the infant’s temperament dimensions in the regression analyses. None of these interactions were significant, indicating that mothers’ and infants’ temperaments have independent effects.
Although the preference for sweet flavors is innate (12
), infants with more distress-prone temperaments may have an even stronger preference and their mothers may learn that these flavors are more readily accepted. Genes influence appetite regulation from as early as the first three months, and infants who are more avid suckers in the first three months are at greater risk for adiposity over the next three years (36
). Infants who are more avid suckers are more inhibited (show more internalizing behavior) at 18 months (37
), suggesting that appetite regulation and internalizing traits may have a common genetic basis in sensory sensitivity and responsivity, which may be implicated in obesogenic feeding styles. It is also likely that there is a reciprocal relation between the behavior of the infant and the mother. The more the mother feeds sweet foods and drinks, the more the infant is likely to prefer these foods. An alternative explanation is that that feeding sweet foods and drinks leads to increases in distress-prone temperament, as infants’ distress is reinforced by sweet foods. The finding for surgency/extraversion was not predicted so requires replication. It could indicate that active children use more calories and therefore are more often hungry at night, and their mothers may perceive them as not weighing enough. Regardless of the underlying mechanisms, the independent effects of child temperament observed here indicate that potentially obesogenic early dietary patterns are associated with infant distress-prone and surgent temperament.
Limitations of this study include the cross-sectional design that precluded any definitive causal directions of effects to be inferred. Because temperament has a heritable component (3
), mothers and infants are likely to share a genetic predisposition for negative affectivity, but this could not be examined here. All the data in this study were derived from one source: mothers’ reports. Although mothers provided detailed food-frequency information on their dietary choices for their infants, we do not know what proportion of these offerings their infants actually consumed. More comprehensive, classical measures of maternal and child temperament would also have been desirable, but were not feasible in the frame of this multi-disciplinary study. The internalizing scale did not include the full bandwidth of the corresponding CBCL scale, and its internal reliability (coefficient alpha) was low. However findings were consistent across all the three outcomes for this measure. It was not possible to separate the effects of night-time sweet drinks from milk. While both provide extra energy, sweet drinks are devoid of protein and have specifically been associated with obesity in childhood. The items measuring sweet drinks did not specify day-time only, therefore there may have been overlap between this variable and night-time caloric drinks.
In conclusion, this study demonstrated concurrent associations between infant distress-prone temperament, particularly internalizing, and mothers’ feeding of sweet foods and drinks to their 18-month old infants. One of several interpretations of these findings is that infant temperament may evoke specific feeding patterns in mothers, suggesting that health professionals should educate mothers to avoid using sweet foods and drinks to regulate their child’s behavior. It is also important for parents to learn that infants do wake 2–3 times a night, and can be encouraged to use their own regulatory skills to soothe themselves (38
). The long-term effects of establishing an early dietary pattern high in sweet foods and drinks on later childhood overweight and obesity, after the adiposity rebound, have yet to be established. The stability of these dietary patterns, the influence of temperament assessed earlier in time on these patterns, and the relation of dietary patterns in infancy on subsequent overweight and obesity should all be examined in future prospective studies.