Growth in ELBW infants

In recent years, the survival of premature infants with a birth weight < 1,000 g has increased significantly. However, their postnatal growth, if compared to the intrauterine growth of a normal fetus at the same postconceptional age (PCA) remains a challenge. Only few studies about growth in premature infants dealing specifically with Extremely Low Birth Weight (ELBW) babies have been published. Therefore, a French group has conducted a retrospective study on ELBW infants ( Biol Neonate 2005;88:57–65, PubMed ), analysing data on 159 babies admitted to the Neonatal Intensive Care Unit at Hôpital Debrousse, Lyon, France between 1990 and 1996.

Twofold the aims of this study: to evaluate the growth outcome of ELBW infants, with a birth weight < 1,000 g, until 36 months of corrected age (CA) and to relate growth to the influence of different parameters at term and at 36 months term.

In total, 159 ELBW infants were evaluated for weight (Wt), height (Ht) and head circumference (HC) in the considered period. Since 1994, they received early systematic personalized parenteral nutrition. Data were standardized with Z-scores and then a detailed statistical analysis was performed.

The mean birth weight was 851.2 ± 116.5 g. Z-scores decreased from birth to term, at a deeper rate for AGA than for SGA (appropriate/small for gestational age) infants (p<0.005 for Ht, Wt, and HC). Between term and 36 months, growth was better in SGA compared with AGA infants (p=0.003 for Ht). Statistical analysis showed that anthropometric parameters at birth were positive determinants for Wt, Ht and HC at term, and also for Wt and Ht at 36 months. Oxygen therapy after 36 weeks of PCA was a negative determinant influencing growth at 36 months. In fact, children under oxygen therapy after 36 weeks reached a height for age at 3 years 0.65 points below that of children with same birth height and born at the same time. Moreover, children with a chronic lung disease had a HC for age at 3 years 0.69 points below that of the other children, and boys had 0.48 points less than girls.

Furthermore, considering the two study periods, a significant difference of decrease in Z-scores was demonstrated for the weight. Children born between 1994 and 1996 lose less score than those born during the remaining years. This can be a confirmation about the use of a more proactive approach to early postnatal nutrition.

In conclusion, these data showed a decrease in Z-scores for all growth parameters between birth and term, mainly during the first year of life. This ‘catch-up’ growth was greater for SGA than AGA infants, although the SGA babies remained shorter and lighter at 36 months than their AGA counterparts.

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