Prenatal influences on size, velocity and tempo of infant growth: findings from three contemporary cohorts

Abstract

Background: Studying prenatal influences of early life growth is relevant to life-course epidemiology as some of its features have been linked to the onset of later diseases.

Methods: We studied the association between prenatal maternal characteristics (height, age, parity, education, pre-pregnancy body mass index (BMI), smoking, gestational diabetes and hypertension) and offspring weight trajectories in infancy using SuperImposition by Translation And Rotation (SITAR) models, which parameterize growth in terms of three biologically interpretable parameters: size, velocity and tempo. We used data from three contemporary cohorts based in Portugal (GXXI, n=738), Italy (NINFEA, n=2,925), and Chile (GOCS, n=959).

Results: Estimates were generally consistent across the cohorts for maternal height, age, parity and pre-pregnancy overweight/obesity. Some exposures only affected one growth parameter (e.g. maternal height (per cm): 0.4% increase in size (95% confidence interval (CI):0.3; 0.5)), others were either found to affect size and velocity (e.g. pre-pregnancy underweight vs normal weight: smaller size (-4.9%, 95% CI:-6.5; -3.3), greater velocity (5.9%, 95% CI:1.9;10.0)), or to additionally influence tempo (e.g. pre-pregnancy overweight/obesity vs normal weight: increased size (7.9%, 95% CI:4.9;10.8), delayed tempo (0.26 months, 95% CI:0.11;0.41), decreased velocity (-4.9%, 95% CI: -10.8;0.9)).

Conclusions: By disentangling the growth parameters of size, velocity and tempo, we found that prenatal maternal characteristics, especially maternal smoking, pre-pregnancy overweight and underweight, parity and gestational hypertension, are associated with different aspects of infant weight growth. These results may offer insights into the mechanisms governing infant growth.

Figure 1. Predicted weight curves corresponding to the effect sizes reported in Table 5.

A. Predicted weight curves for different categories of maternal smoking during pregnancy. The predicted curve for children exposed to maternal smoking during pregnancy beyond the 1^st trimester lies below that of those not exposed for the first months of life, but then lies above after 4–5 months of life due to their increased velocity. B. Predicted weight curves for different categories of maternal pre-pregnancy BMI. The predicted curve for children of overweight/obese mothers lies above that of children of mothers with a pre-pregnancy BMI between 18.5 and 25, with the difference between the two curves increasing with time.