Intergenerational Changes in Knee Height Among Maya Mothers and Their Adult Daughters from Merida, Mexico

Objectives: To analyze differences in knee height (KH) between adult Maya mothers and daughters in Merida City, Mexico, and determine if these differences are associated with their childhood socioeconomic conditions.
Methods: From September 2011 to January 2014, we measured KH and collected data on childhood conditions (place of birth, type of drinking water, family size, and fathers’ occupation) from a sample of 180 Maya mother-daughter dyads. Mean KH intergenerational difference was calculated and compared for each category of socioeconomic variables and a multiple regression model was used to assess the association between childhood conditions and KH difference.
Results: A relative increase of 1.05 cm (SD52.3 cm) or 0.45 standard deviations (effect size of difference) was
observed in KH between generations. Place of birth was significantly associated with KH. With three other variables
statistically adjusted for, the intergenerational KH difference was 1.5 cm greater when mothers born outside Merida
but daughters born in the city. Piped water consumption by mother-daughter dyads was associated with 1.5 cm of
increase in KH difference compared with dyads who consumed well water (P50.058).
Conclusions: The relative increase in KH between mothers and daughters represents a portion of the expected
change in growth in a group that has experienced few substantial improvements in their living conditions. Some improvements in childhood living conditions resulting from the intergenerational transition from rural to urban environments
seem to be linked to a modest, but statistically significant intergenerational increase in KH among Maya women in Merida. Am. J. Hum. Biol. 00:000–000, 2015.