Variations in birth weight within the normal range are related to visual orienting in infancy for boys but not for girls

Abstract

Pooling across 27 experiments on visual orienting during early infancy generated a large sample of full-term infants with birth weights greater than 2500 g (N = 944). A weight-for-date measure was obtained separately for girls and for boys by residualizing birth weight on gestational age at birth. The proportion of trials with orienting toward a moving target increased directly with this weight-for-date measure for boys but not for girls in a linear regression with adjustments for gestational age at testing, birth order and visual stimulus parameters across experiments. The same relations held when raw birth weight was used as a predictor. For the 475 boys, the z-score of the orienting measure increased by 0.221 for each kilogram increase in birth weight corrected for gestational age (0.196 z-units per kilogram adjusted for covariates, 95% CI = 0.04-0.35 z-units per kg, P = 0.014). The interaction of gender and birth weight in this association makes explanations based on confounding family social variables less tenable as explanations. This association primarily for boys is similar to recently reported associations between birth weight and IQ during childhood. Possible factors underlying this association such as prenatal nutrition are discussed.

Effects of gestational length, gender, postnatal age, and birth order on visual contrast sensitivity in infants

“…Of course, this account must be considered in any study that finds a correlation between a measure of physiological maturity at birth (e.g., gestational length, weight, length, or head circumference) and an outcome measure. In fact, there is a sizeable literature showing that different aspects of physiological maturity at birth predict visual performance (visual orienting at 2 to 5 months: Dannemiller, 2004; attention to faces at 4 to 6 months: Camp, Jamieson-Darr, Hansen, & Schmidt, 1990; visual recognition memory from 5 to 12 months: Rose, 1994) and non-visual performance (language and gross movement at 4 years: Ounsted, Moar, & Scott, 1984; IQ in childhood: Churchill, 1965; Jefferis, Power, & Hertzman, 2002; Matte, Bresnahan, Begg, & Susser, 2001; Scarr, 1969). Analyses that control for prenatal environment factors will help determine whether correlations observed between physiological measures of maturity at birth and later visual performance (as in the current and previous studies) are driven by these factors.…”

“…Raising this possibility is motivated by reports that the relationship between BW and visual orienting in 2- to 5-month-old infants (Dannemiller, 2004)6 and between BW and IQ in 7-year-olds (Matte et al, 2001) is significantly stronger for boys than girls. Given that maternal nutrition has an effect on both BW and later visual/non-visual performance (see above), these larger effects of BW for boys might be accounted for by the fact that the link between maternal nutrition and BW has been shown to be greater for boys (Mora et al, 1981; possibly because boys grow faster, see discussion in Dannemiller, 2004). In the current study, the MRA did not reveal an effect of BW on our visual measure, i.e., contrast sensitivity.…”

“…The ANCOVA also allowed us to confirm/ disconfirm effects that were seen in the MRA (for example gender effects) or effects that were seen in the MRA that could not be tested statistically (for example, a reversal in the effect of BO between 2 and 6 months). The ANCOVA was also used to test specific interactions that test hypotheses based on results from previous studies (Dannemiller, 2004 reported an interaction between gender and BW on a visual performance measure in 2- to 5-month-olds; see Discussion). In the ANCOVA, CS type was the repeated-subjects variable, Age Group, Gender, and BO were between-subjects factors, and PNA, BW, and GL were included as covariates.…”

Executive Functions of Six-Year-Old Boys with Normal Birth Weight and Gestational Age

“…We anticipated that variations in fetal growth and maturity across the normal population would result in relatively subtle differences in specific functions; thus we focused upon six-year-old boys to avoid possible heterogeneous gender or age outcomes. Previous studies demonstrate males are more susceptible to adverse prenatal circumstances [20], [21] and exhibit strong association of prenatal circumstances to general intelligence [11] and visual attention [22]. Furthermore, subtle cognitive differences are likely to be more consequential at this age as formal schooling requires children to adjust to new experiences and greater cognitive and behavioral demands [2].…”

MAOA Influences the Trajectory of Attentional Development

“…To answer this question, we recruited participants from a follow up sample of children who participated as infants in visual attention studies (Dannemiller, 2004). We use RT and PC to index performance on a reflexive attention task.…”