Birth Size and Maternal, Social, and Environmental Factors in the Province of Jujuy, Argentina.

Introduction: birth size is affected by diverse maternal, environmental, social, and economic factors.

Aim: analyze the relationships between birth size-shown by the indicators small for gestational age (SGA) and large for gestational age (LGA)-and maternal, social, and environmental factors in the Argentine province of Jujuy, located in the Andean foothills.

Methods: data was obtained from 49,185 mother-newborn pairs recorded in the Jujuy Perinatal Information System (SIP) between 2009 and 2014, including the following: newborn and maternal weight, length/height, and body mass index (BMI); gestational age and maternal age; mother's educational level, nutritional status, marital status and birth interval; planned pregnancy; geographic-linguistic origin of surnames; altitudinal place of birth; and unsatisfied basic needs (UBN). The dataset was split into two groups, SGA and LGA, and compared with adequate for gestational age (AGA). Bivariate analysis (ANOVA) and general lineal modeling (GLM) with multinomial distribution were employed.

Results: for SGA newborns, risk factors were altitude (1.43 [1.12-1.82]), preterm birth (5.33 [4.17-6.82]), older maternal age (1.59 [1.24-2.05]), and primiparous mothers (1.88 [1.06-3.34]). For LGA newborns, the risk factors were female sex (2.72 [5.51-2.95]), overweight (1.33 [1.22-2.46]) and obesity (1.85 [1.66-2.07]).

Conclusions: the distribution of birth size and the factors related to its variability in Jujuy are found to be strongly conditioned by provincial terrain and the clinal variation due to its Andean location.