Longitudinal study of the maternal insulin-like growth factor system before, during and after pregnancy in relation to fetal and infant weight.
BACKGROUND
The maternal insulin-like growth factor (IGF) system is considered to be involved in fetal growth regulation. However, available data linking this system to fetal growth are contradictory and incomplete.


OBJECTIVE
To measure components of the IGF system before, during and after pregnancy in healthy women and to relate these results, and their changes during pregnancy, to fetal weight (gestational week 31) and birth weight.


METHODS
Serum concentrations of IGF-I, IGF-II, IGF-binding protein (IGFBP)-1, IGFBP-3 and IGFBP-3 protease activity were assessed in 23 women before conception, at weeks 8, 14, 20, 32 and 35 of pregnancy and 2 weeks postpartum. The data were analyzed using simple and multiple linear regression.


RESULTS
One third of the variability in fetal weight was explained by IGF-I in combination with IGFBP-3 protease activity, both assessed at gestational week 32 (p = 0.013). Birth weight was negatively correlated (r = -0.43 to -0.59) with IGFBP-1 at gestational week 20 (p = 0.041), 32 (p = 0.012) and 35 (p = 0.003).


CONCLUSIONS
We propose there is a finely tuned balance among the components of the IGF system, providing a means for fetal growth regulation.
Department of Biomedicine and Surgery, Division of Nutrition, Linkoping University, Linkoping, Sweden. hanol@ibk.liu.se
H
H
Olausson
M
M
Lof
K
K
Brismar
M
M
Lewitt
E
E
Forsum
A
A
Sohlstrom
D000328:Adult; D001724:Birth Weight / Q000502:physiology*; D005260:Female; D047109:Fetal Development / Q000502:physiology; D020567:Fetal Weight / Q000502:physiology*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D018969:Insulin-Like Growth Factor Binding Proteins / Q000097:blood*; D008137:Longitudinal Studies; D033261:Maternal-Fetal Relations; D009035:Mothers; D049590:Postpartum Period / Q000097:blood; D011247:Pregnancy / Q000097:blood; D013002:Somatomedins / Q000032:analysis* / Q000502:physiology*
D018969:Insulin-Like Growth Factor Binding Proteins; D013002:Somatomedins