Published online March 27, 2006
PEDIATRICS Vol. 117 No. 4 April 2006, pp. e793-e795 (doi:10.1542/peds.2005-1705)

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Preterm Growth Restraint: A Paradigm That Unifies Intrauterine Growth Retardation and Preterm Extrauterine Growth Retardation and Has Implications for the Small-for-Gestational-Age Indication in Growth Hormone Therapy

J.M. Wit, MD, PhD^a, M.J.J. Finken, MD^a, M. Rijken, MD^a and F. de Zegher, MD, PhD^b

^a Department of Pediatrics, Leiden University Medical Center, Leiden, Netherlands
^b Department of Pediatrics, University of Louvain, Louvain, Belgium

Abbreviations: SGA, small for gestational age • IUGR, intrauterine growth retardation • EUGR, extrauterine growth retardation • GH, growth hormone • PGR, preterm growth restraint

The first 20% of the full text of this article appears below.

Small for gestational age (SGA) is defined as a birth weight and/or length >2 SDs below the gender-specific population reference mean for gestational age. However, there is confusion about various aspects of this term, as recently discussed.^1,2 The term "intrauterine growth retardation" (IUGR) is often used for the same condition but preferably should be restricted to poor growth during pregnancy according to intrauterine growth diagrams used in obstetrics.³ SGA after a normal duration of gestation (37–42 weeks) is usually followed by rapid growth after birth (catch-up growth). It has been demonstrated that almost 90% of term SGA infants catch up in height in the first 2 years of postnatal life.^4,5

On average, the human male has a birth length of 51 cm after term gestation and a final height, in the Netherlands, of 184 cm. Thus, in the 9 months before birth, he has reached almost 30% of his adult height potential. Fetal length velocity at midgestation is >10-fold higher than pubertal peak height velocity (Fig 1).

View larger version (10K): [in this window] [in a new window]   FIGURE 1 Normal length/height velocity from conception to adulthood (boys). Fetal length velocity reaches its maximum during midgestation, 10 cm/month, and declines to 35 cm/year around birth. In comparison, the median for peak height velocity during puberty is 9.42 cm/year. Postnatal height velocity (median values) is according to Dutch reference values.13

 
Thus, very preterm infants are exposed to extrauterine life during a period that normally is characterized by rapid intrauterine growth. To survive, their energy expenditure shifts from growth-promoting actions to survival strategies to cope with the increased requirements of unintended postnatal life. Extrauterine growth retardation (EUGR) is often the result. Preterm infants whose mothers suffered . . . [Full Text of this Article]

Address correspondence to J.M. Wit, MD, PhD, Department of Pediatrics, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, Netherlands. E-mail: j.m.wit@lumc.nl

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