Birth Characteristics and Risk of Low Intellectual Performance in Early Adulthood: Are the Associations Confounded by Socioeconomic Factors in Adolescence or Familial Effects?

Abstract

We found that all of the studied dimensions of restricted fetal growth are independently associated with increased risks of low intellectual performance and that these associations are only partly mediated by socioeconomic or familial factors.

Risks for Low Intellectual Performance Related to Being Born Small for Gestational Age Are Modified by Gestational Age

“…Included covariates are listed in the footnotes to the tables and have been described in detail elsewhere. 8 …”

“…8 Briefly, we included information from 4 population-based registries: the Swedish Medical Birth Register, the Swedish Conscript Register, the Multi-Generation Register, and the Population and Housing Census of 1990. Record linkage was possible using the unique National Registration Number that is assigned to each Swedish resident at birth.…”

“…[1][2][3][4][5][6][7] We showed previously that risks for low intellectual performance related to short gestational age and indicators of reduced fetal growth (low birth weight, short birth length, and a small head circumference for gestational age) remain after controlling for socioeconomic and familial factors. 8 It has been hypothesized that the impact of fetal growth restriction on the child's long-term cognitive and motor development varies with gestational age at birth. 9,10 A number of studies reported increased risks for low intellectual performance and poor cognitive development among growth-restricted infants who were delivered at or near term.…”

Birth Weight and Cognitive Ability in Childhood Among Siblings and Nonsiblings

“…Several such family-based studies have been conducted for birth weight and cognitive ability. [21][22][23][24][25] In the earliest study, Record et al 21 showed that differences in cognitive ability between nonsiblings aged 11 years in England were greater than those of 2521 sibling pairs and concluded that the association was largely because of confounding by SEP. A study by Lawlor et al 24 also found that, although birth weight was positively associated with cognitive ability at ages 7 to 11 years in a wholecohort analysis, there was no association within 1645 sibling pairs. By contrast, 3 studies have found positive within-sibling associations.…”

Antenatal Counseling Regarding Resuscitation at an Extremely Low Gestational Age

“…3,20,21 Another limitation is that many other factors influence the outcome of infants besides gestational age. 19,[22][23][24][25][26][27][28] Data from the National Institute of Child Health and Development Neonatal Research Network have been used to create an algorithm predicting outcome that considers birth weight, gender, use of prenatal steroids, and singleton pregnancy in addition to estimated gestational age. 19 Each of these factors individually improves outcome for infants by as much as 1 additional week of gestation from 22 through 25 weeks' gestation.…”