ESPE Abstracts (2014) 82 P-D-1-2-152

Longitudinal Growth of Healthy Preterm Infants Born Below 37 Gestation Weeks

Niina Hyvönena,b, Panu Kivirantac, Antti Saaric, Leo Dunkeld & Ulla Sankilampic


aCentral Finland Central Hospital, Jyväskylä, Finland; bUniversity of Eastern Finland, Kuopio, Finland; cKuopio University Hospital, Kuopio, Finland; dQueen Mary University of London, London, UK


Background: The ideal pattern of postnatal growth for preterm infants is unknown. Existing preterm growth charts are based on cross-sectional birth size data, and fail to describe longitudinal growth adequately.

Objective and hypotheses: We collected longitudinal growth data of healthy preterm infants and constructed growth references from birth to term equivalent age (TEA). Our aim was to describe optimal growth under contemporary neonatal care, in comparison to babies born at same gestational age.

Method: Data of 3067 infants born at 24–36 gestation weeks (GW) were evaluated. Infants with pre- or postnatal conditions possibly affecting growth were excluded. The final study population consisted of 1303 preterm infants in three GW groups (80, 169, and 1,054 infants born at 24–27, 28–31, and 32–36 GW, respectively, 55.0% boys) with 3807/3284 weight/length measurements. Data were converted to SD using contemporary birth size references. Longitudinal growth was summarized as median curves for each postmenstrual (PM) week until TEA. Median curves were fitted by a cubic smoothing spline in R-program.

Results: Birth weight and length varied between −2.0 and 2.0SD. After birth, catch-down growth occurred in all GW groups apart from growth in length in infants born at 32–36 GW. Catch-up growth started after 34 PM weeks. At TEA, the median weights were −2.0/−1.8, −0.60/−0.50, −0.60/−0.50 SD and the median lengths were −2.3/−1.8, −0.40/−0.30,−0.10/0.20SD in boys/girls born at 24–27, 28–31, and 32–36 GW, respectively (Table 1).

Table 1.
Percentage of infants with weight/length <−2SD at TEA
Gestation weeksWeight (boys/girls)Length (boys/girls)
24−27+636.0/38.956.0/36.8
28−31+612.3/6.78.8/2.3
32−36+61.1/2.10.4/0.4

Conclusion: Despite modern neonatal care, still 30–40% of the healthy extremely preterm infants have extrauterine growth failure at TEA when compared to growth in utero. However, the ideal growth pattern of extrauterine growth in preterm infants may not be the same as the growth in utero.

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