Wiener G. The relationship of birth weight and length of gestation to intellectual development at ages 8 to 10 years. J Pediatr 1970;76:694-9.
The understanding that infants weighing ≤2500 g at birth are not all premature represents one of the biggest leaps forward in neonatology. Peter Gruenwald pointed out that some are small because they do not grow normally in utero.1x1Gruenwald, P. Terminology of infants of low birth weight. Dev Med Child Neurol. 1965;
Crossref | PubMed | Google ScholarSee all References Wiener’s objective was to illustrate that birth weight has a bigger implication on development than gestational age in his article in The Journal 50 years ago. He matched 500 low birth weight with 492 full-term single born children from a cohort born in 1952. At the age of 8-10 years, 822 of these children were examined using different tests such as the Wechsler Intelligence Scale for children. The results showed that at any given birth weight group within the low birth weight range, the length of gestation was not related to intellectual impairment. These results are to some extent, however, not completely in agreement with more recent studies. A Swedish study including 350 000 boys born in 1973-1981 found that neonates with a gestational age of 28-36 weeks with normal birth weight for gestational age, were not at increased risk for low intellectual performance. However, those who were born small for gestational age had an almost doubled risk for low intellectual performance.2x2Bergvall, N., Iliadou, A., Johhansson, S., Tuvemo, T., and Cnattingius, S. Risks for low intellectual performance related to being born small for gestational age are modified by gestational age. Pediatrics. 2006;
Crossref | Scopus (43) | Google ScholarSee all References In his study, Wiener did also find a correlation between high birthweight, shorter gestational age, and poor outcome. This was, and is, a puzzle. The possible explanations given were that the gestational ages were incorrect and that bleeding in the first trimester (explaining the misconception of short gestational period) could correlate with poor intellectual outcome. This illustrates how prenatal care has improved in the last 50 years, with the introduction of ultrasound-guided assessments of gestational length.