Leptin, insulin, insulin-like growth factors and their binding proteins in cord serum: insight into fetal growth and discordancy.
OBJECTIVE
Singleton infants with intrauterine growth restriction have an adaptive hormonal profile characterized by decreased levels of IGF-1, IGF-2, IGFBP-3 and insulin and elevated levels of IGFBP-1 and IGFBP-2. This study examined the association between cord serum levels of six growth factors and anthropometric features at birth in twins in order to determine the intrauterine growth factor interactions and to characterize the specific hormonal profile of small discordant twins.


METHODS
Prevalent case-control study.


METHODS
Twenty pairs of discordant twins (5 monozygotic, 15 dizygotic) and 20 pairs of concordant twins (6 monozygotic, 14 dizygotic) matched for gestational age.


METHODS
Cord blood levels of IGF-1, IGF-2, IGFBP-1, IGFBP-3, insulin, leptin and anthropometric measurements at birth. Intra- and inter-pair differences and correlation coefficients were calculated, and the data were fitted to multivariate regression models.


RESULTS
In both discordant and concordant groups, the smaller twins had a significantly lower level of IGF-1 (P < 0.03) and significantly higher level of IGFBP-1 (P < 0.02) than their larger cotwins. IGFBP-1 was inversely correlated with IGF-1 (P < 0.05). Insulin levels were significantly higher in the smaller discordant than the smaller concordant twins (P < 0.001) and in the larger discordant than the larger concordant twins (P < 0.004). Among the monozygotic twins, the leptin level was significantly higher in the larger discordant than the larger concordant twins (P < 0.025). Percentage birth weight discordancy was statistically correlated with twin-pair differences in IGF-1 and IGFBP-1.


CONCLUSIONS
Of the six factors studied, IGF-1 appears to be the main indicator of intrauterine growth. Twin discordancy may involve compensatory rather than adaptive mechanisms or a multihormone relative resistance syndrome.
Davidson
S
S
Department of Neonatology, Women's Comprehensive Health Care Centre, Rabin Medical Centre, Petah Tiqva, Israel. shmueld@clalit.org.il
Hod
M
M
Merlob
P
P
Shtaif
B
B
D001724:Birth Weight; D016022:Case-Control Studies; D004200:Diseases in Twins; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D005317:Fetal Growth Retardation / Q000097:blood*; D005865:Gestational Age; D006801:Humans; D015592:Immunoradiometric Assay; D007231:Infant, Newborn; D007328:Insulin / Q000097:blood*; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D020738:Leptin / Q000097:blood*; D011247:Pregnancy; D011863:Radioimmunoassay; D012044:Regression Analysis; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic
D007328:Insulin; D018970:Insulin-Like Growth Factor Binding Protein 1; D020738:Leptin; D007334:Insulin-Like Growth Factor I