Bucher et al report the results of a questionnaire sent to parents of Swiss infants born before 32 weeks of completed gestation.  The parents were asked to answer questions concerning weight, body length, head circumference at 24 months of age, developmental milestones, eye and ear problems, long-term medications, fever, cough, and infectious diseases during the last 12 months.   Information regarding developmental milestones is recorded in the Swiss Health Carnet given to each parent of a newborn infant.  A comparison group for this study included two control infants for each index infant.  The second was contacted if the first did not respond.  Infants of multiple births or with severe malformations or syndromes were excluded.  The control infants had to have been born in the same hospital, at term (after 37 weeks), and within 14 days of the expected date of birth of the index infant, and of the same gender as the index infant.

Three hundred nine infants born between January 1, 1996 and December 31, 1996 were included. Index infants had significantly lower body weight, body length, and smaller head circumference at 24 months corrected age as compared to their matched control.  The mean weight difference at the age of 2 years (corrected for the very preterm infants) was 1.2 kg for boys, and 1.2 kg for girls.  The mean difference in body length was 3.5 cm for girls and 3.3 cm for boys.  Thirty-three percent of index infants were below the third percentile for length at 24 months corrected.  The difference in head circumference was small (0.7 cm), but statistically significant (p < 0.001).  Height and weight parameters were similar in the parents of pre-term and term infants, and in agreement with normal growth standards for adults.  In the very preterm infants, there was significant motor delay, increase in eye problems and in use of long-term medications, but no difference in infectious diseases during the prior 12 months.  Sitting was not delayed, but walking (mean of 14.5 months vs 13.5 months in controls (p=0.4) and drinking out of a cup (50% of each group at 16.5 vs 13.5 months; p=<0.001) were delayed.  Of the very preterm infants, 16% were unable to walk independent at 18 months corrected age. These infants are at increased risk for developing cerebral palsy.  The authors state that such a retrospective study can include much bias, but that has been accounted for by utilizing a significantly large control group. The cause of significant growth delay remains unclear.  Suggested causes include: (1) decreased length of gestation; (2) insufficient supply of nutrients over prolonged periods of time after birth; or (3) intercurrent illnesses in the first year, such as chronic lung disease which may increase energy requirements and interfere with nutrient intake.

Editor’s Comment: The authors recall several studies in which catch-up growth in pre-term infants has been stated to occur up until adolescence, and note that the patients in this study should be followed at least through school age. The data are intriguing however, for several other reasons. First, it is possible that these very young children (less than 30 weeks gestation) may respond with accelerated growth to recombinant growth hormone therapy in much the same way as do children with intrauterine growth retardation. Initiation of such therapy at a young age might significantly improve not only final height, but developmental milestones as well. The discrepancy in head circumference in the very pre-term infant, although minimal, is nonetheless of considerable concern.  Thus as the authors point out, it would be important to carefully record growth patterns, and developmental milestones over time in the attempt to define those children who might benefit most from earlier hormonal investigation and intervention. It would appear that the Swiss Minimal Neonatal Data Set is an excellent resource for the collection and analysis on such data. 

 William L. Clarke, MD