Effect of birth weight and nutritional status on transverse maxillary growth: Implications for maternal and infant health.

We analyzed the association between birthweight, nutritional status and transverse maxillary growth in 7- to 9-year-old schoolchildren. We undertook a cross-sectional survey nested in a population-based cohort study of 158 schoolchildren. The participants lived in the urban area of a small town within the Western Brazilian Amazon. The outcome was represented by the upper intermolar distance given in millimeters (mm), as an indicator of the degree of maxillary bone growth in its transverse dimension. The exposures were sex, birthweight, the bottle-feeding pattern operationalized by a scale corresponding to the age of introduction of the bottle and Body Mass Index-for-age z-score (BAZ) at 4 to 6 ys. Path analysis was employed to estimate standardized direct, indirect and total effects of exposures on the outcome using structural equations model (SEM) supported by Mplus 7 program. The values of standardized coefficients (SC) showed significant direct positive effects of sex (SC = 0.203; p = 0.006), birth weight (SC = 0.155; p = 0.030) and BAZ (SC = 0.165; p = 0.014) on transverse maxillary growth. The indirect effects (SC = 0.057; p = 0.012) and the total effect (SC = 0.261; p<0.001) of sex on the outcome were statistically significant. The indirect effects of birth weight on the outcome were not significant (SC = 0.018; p = 0.488), however, the total effect was significant (SC = 0.174; p = 0.011). In conclusion, sex, birthweight, bottle beginning age and BAZ showed association with the transverse growth of the maxillary bone. In addition to contributing to an adequate birth weight of the child, policies and programs that favor prenatal care and conditions to guarantee a full-term birth can positively affect transverse growth of the maxilla. From a Public Health Surveillance point of view, children with reduced birthweight, inadequate breastfeeding pattern and nutritional deficit for age may be more likely to develop atrophy of the jaws which, depending on the severity, may result in malocclusion with an important impact on quality of life.