Background: There is increasing evidence that poor growth of preterm infants is a risk factor for poor long-term development, while the effects of early postnatal growth restriction are not well known. We utilized a rat model to examine the consequences of different patterns of postnatal growth and hypothesized that early growth failure leads to impaired development and insulin resistance. Rat pups were separated at birth into normal (N, n = 10) or restricted intake (R, n = 16) litters. At d11, R pups were re-randomized into litters of 6 (R-6), 10 (R-10) or 16 (R-16) pups/dam. N pups remained in litters of 10 pups/dam (N-10). Memory and learning were examined through T-maze test. Insulin sensitivity was measured by i.p. insulin tolerance test and glucose tolerance test. Results: By d10, N pups weighed 20 % more than R pups (p < 0.001). By d15, the R-6 group caught up to the N-10 group in weight, the R-10 group showed partial catch-up growth and the R-16 group showed no catch-up growth. All R groups showed poorer scores in developmental testing when compared with the N-10 group during T-Maze test (p < 0.05). Although R-16 were more insulin sensitive than R-6 and R-10, all R groups were more glucose tolerant than N-10. Conclusion: In rats, differences in postnatal growth restriction leads to changes in development and in insulin sensitivity. These results may contribute to better elucidating the causes of poor developmental outcomes in human preterm infants.

Objective

Survival of preterm and very low birth weight (VLBW) infants has steadily improved. However, the rates of mortality and morbidity among the very smallest infants are poorly characterized.

Study design

Data from the California Perinatal Quality Care Collaborative for the years 2005 to 2012 were used to compare the mortality and morbidity of profoundly low birth weight (ProLBW, birth weight 300 to 500 g) and profoundly small for gestational age (ProSGA, <1st centile for weight-for-age) infants with very low birth weight (VLBW, birth weight 500 to 1500 g) and appropriate for gestational age (AGA, 5th to 95th centile for weight-for-age) infants, respectively.

Result

Data were available for 44 561 neonates of birth weight <1500 g. Of these, 1824 were ProLBW and 648 were ProSGA. ProLBW and ProSGA differed in their antenatal risk factors from the comparison groups and were less likely to receive antenatal steroids or to be delivered by cesarean section. Only 14% of ProSGA and 21% of ProLBW infants survived to hospital discharge, compared with >80% of AGA and VLBW infants. The largest increase in mortality in ProSGA and ProLBW infants occurred prior to 12 h of age, and most mortality happened in this time period. Survival of the ProLBW and ProSGA infants was positively associated with higher gestational age, receipt of antenatal steroids, cesarean section delivery and singleton birth.

Conclusion

Survival of ProLBW and ProSGA infants is uncommon, and survival without substantial morbidity is rare. Survival is positively associated with receipt of antenatal steroids and cesarean delivery.