Insulin-like growth factor (IGF)-I and insulin in normal and growth-restricted mother/infant pairs

Placental proteases PAPP-A and PAPP-A2, the binding proteins they cleave (IGFBP-4 and -5), and IGF-I and IGF-II: Levels in umbilical cord blood and associations with birth weight and length

BACKGROUND

A newborn's birth weight for gestational age provides important insights into his or her fetal growth and well-being. While the underlying mechanisms regulating fetal growth remain to be fully elucidated, the IGF axis plays an important role. Some components of this axis have been well-characterized in umbilical cord blood, but others have not yet been studied. We measured the proteases PAPP-A and PAPP-A2, the binding proteins they cleave (IGFBP-4 and -5), and the established molecules IGF-I and -II in umbilical cord blood to better characterize the IGF axis in relation to birth weight and length.

METHODS

We performed a case-control study of 180 neonates born at a tertiary teaching hospital in Boston. To maximize power, infants were recruited in a 1:3:1 ratio with 37 SGA, 111 AGA, and 37 LGA infants matched by gestational age, sex, and delivery mode. IGF-I, IGF-II, IGFBP-4, IGFBP-5, PAPP-A, and PAPP-A2 were measured in umbilical cord blood by ELISA. Associations between birth weight and birth length Z-scores and the Z-scores of the above molecules were analyzed using linear regression models and analysis of covariance.

RESULTS

Birth weight and length Z-scores were positively associated with Z-scores of IGF-I, IGF-II, total IGFBP-4, and IGFBP-5, with IGF-I having the strongest association. Birth weight and length Z-scores were negatively associated with Z-scores of intact IGFBP-4, PAPP-A, and PAPP-A2 levels.

CONCLUSIONS

We confirm previous findings of significant associations between the IGFs in cord blood and newborn size and for the first time show positive associations between cord blood total IGFBP-4 and -5 and birth weight and a negative association between intact IGFBP-4 and birth weight. We also show for the first time a reciprocal relationship between cord blood levels of PAPP-A and PAPP-A2 and newborn size. The implications of these findings need to be further examined in large longitudinal studies and likely have diagnostic and therapeutic potential.

Early postnatal alteration of body composition in preterm and small-for-gestational-age infants: implications of catch-up fat

The concept of the developmental origins of health and disease is based on studies by Barker et al. They proposed a hypothesis that undernutrition in utero permanently changes the body's structure, function, and metabolism in ways that lead to atherosclerosis and insulin resistance in later life. In addition, profound effects on the extent of body fatness and insulin sensitivity are demonstrated, if there is a "mismatch" between prenatal and postnatal environments. In previous studies, undernutrition in utero has been evaluated simply by birth weight itself or birth weight for gestational age, and the degree of mismatch has been estimated by postnatal rapid weight gain. Recently, we investigated subcutaneous fat accumulation in small-for-gestational-age infants and found that a rapid catch-up in skinfold thickness developed prior to the body weight catch-up. Furthermore, insulin-like growth factor-I and lipoprotein lipase mass concentrations also demonstrate rapid increase during the neonatal period with fat accumulation. Investigating the precise mechanisms of developmental origins of health and disease including mediating metabolic and hormonal factors may provide a new approach to prevent atherosclerosis and insulin resistance. Better management of undernutrition during gestation and neonatal growth during the early postnatal period is an important theme for future health.

Nationwide inventory of risk factors for retinopathy of prematurity in the Netherlands

OBJECTIVES

To study the incidence and risk factors for retinopathy of prematurity (ROP) in the Netherlands.

STUDY DESIGN

Prospective, approximating population-based study that included infants with gestational age (GA) <32 weeks and/or birth weight (BW) <1500 g born in 2009. Pediatricians and ophthalmologists of all hospitals involved in care for premature infants reported data that were matched with the national perinatal database for risk factor analysis.

RESULTS

Of 1380 infants, median GA 29.8 weeks (IQR 28.1-31.1) and median BW 1260 g (IQR 1020-1500), ROP developed in 21.9%. Logistic regression identified GA and BW as risk factors for ROP (P < .001). After adjustment for GA and BW, additional risk factors were inhaled nitric oxide (iNO; OR 2.6, 95% CI 1.1-6.2, P = .03), stay at a neonatal intensive care unit >28 days (OR 1.6, 95% CI 1.1-2.6, P = .03), and artificial ventilation >7 days (OR 1.6, 95% CI 1.1-2.5, P = .02). Prenatal glucocorticoids (OR 0.6, 95% CI 0.4-0.8, P < .001) and female sex (OR 0.7, 95% CI 0.5-0.99, P = .04) showed a lesser incidence of ROP. iNO remained significant after correction for all significant factors (OR 2.6, 95% CI 1.1-6.2, P = .03).

CONCLUSION

In addition to established risk factors (GA, BW, stay at a neonatal intensive care unit >28 days, and artificial ventilation >7 days), treatment with iNO as risk factor for ROP is a novel finding.

Omentin-1 and vaspin are present in the fetus and neonate, and perinatal concentrations are similar in normal and growth-restricted pregnancies

The aim of this study was to investigate circulating concentrations of omentin-1 and vaspin (adipocytokines predominantly secreted by visceral adipose tissue and not yet investigated in perinatal life) in maternal, fetal, and neonatal samples from intrauterine growth-restricted (IUGR; associated with altered development of adipose tissue) and appropriate-for-gestational-age (AGA) pregnancies and to correlate them with the respective insulin concentrations. Serum omentin-1 and vaspin concentrations were determined by enzyme immunoassay in 40 mothers and their 20 IUGR and 20 AGA singleton full-term fetuses and neonates on postnatal day 1 (N1) and day 4 (N4). Both hormones were detectable in fetal and neonatal blood (omentin-1 [mean ± SD, in nanograms per milliliter]: AGA vs IUGR group--fetal: 11.32 ± 1.88 vs 10.47 ± 1.30, N1: 10.74 ± 1.42 vs 10.46 ± 1.54, and N4: 10.90 ± 2.72 vs 11.35 ± 3.92; vaspin [median, minimum-maximum; in nanograms per milliliter]: AGA vs IUGR group--fetal: 0.39 [0.04-19.06] vs 0.40 [0.05-1.34], N1: 0.40 [0.04-16.70] vs 0.44 [0.23-3.34], and N4: 0.49 [0.02-8.89] vs 0.55 [0.06-3.92]). No significant differences in omentin-1 or vaspin concentrations were observed between IUGR and AGA groups, whereas fetal and N1 insulin concentrations were lower in the former (P = .025 and P = .027, respectively). In both groups, fetal omentin-1 concentrations were higher (P ≤ .018), whereas vaspin concentrations were lower (P ≤ .001), than maternal ones. Furthermore, maternal vaspin concentrations were higher in cases of cesarean delivery (P = .024). Omentin-1 and vaspin concentrations did not correlate with the respective insulin ones. In conclusion, omentin-1 and vaspin are present in the fetus and neonate. Perinatal concentrations of omentin-1 and vaspin are similar in IUGR cases and AGA controls--despite lower insulin concentrations in the former--and do not correlate with the respective insulin concentrations. Higher omentin-1 concentrations in the fetus may be crucial to enhance a growth-promoting effect, whereas lower maternal vaspin concentrations in cases of vaginal delivery may be attributed to spontaneous term delivery inflammation.

Reduction of IGF-binding protein-3 as a potential marker of intra-uterine growth restriction

BACKGROUND

Growth factor-binding proteins influence the growth of infants starting in utero. Adaptation of the fetus to an adverse uterine environment is associated with changes in the growth hormone-growth factor-insulin axis.

AIMS

To evaluate serum levels of IGF-I and IGFBP-3 in small and appropriate for gestational age newborn infants.

METHODS

Fifty-four newborn infants, small (SGA, n=28) or appropriate (AGA, n=26) for gestational age were matched by gestational age and sex. Blood was collected on the first day of life, and anthropometric measurements were taken at birth. The serum levels of IGF-I and IGFBP-3 were compared, and correlated with the anthropometric measurements.

RESULTS

On the first day of life, mean serum IGFBP-3 levels were significantly lower in SGA babies and correlated with weight, length, head circumference, and ponderal index (weight/length 3) (P<0.0001). In contrast, no associations were found between IGF-I serum levels and these anthropometric measurements.

CONCLUSION

Our data show that SGA babies have significantly reduced IGFBP-3 concentrations at birth.