Maternal insulin-like growth factor binding protein-1, body mass index, and fetal growth.
OBJECTIVE
To examine the hypothesis that the maternal insulin-like growth factor system may constrain fetal growth.


METHODS
A prospective observational study of maternal serum insulin-like growth factor binding protein-1 (IGFBP-1) and fetal growth was undertaken in neonates with birthweights below the 5th centile. They had been classified either as having fetal growth restriction (FGR) due to placental dysfunction (increased umbilical artery Doppler pulsatility index (PI); n = 25) or as being small for gestational age (SGA; normal umbilical artery PI, growth velocity and amniotic fluid; n = 27). Eighty nine controls had normal birthweights (5th-95th centile), umbilical artery PI, growth velocity, and amniotic fluid. IGFBP-1 was measured by radioimmunoassay.


RESULTS
Among the controls, there was no significant correlation between IGFBP-1 and birthweight after allowing for body mass index (BMI). Maternal BMI was high in FGR and after adjusting for this, IGFBP-1 was increased (109 ng/ml) compared with SGA babies (69 ng/ml) and controls (57 ng/ml) and correlated with the umbilical artery PI.


CONCLUSIONS
Maternal IGFBP-1 is probably not part of normal placental function. Its increase in FGR could be the cause or consequence of impaired placental perfusion, but high IGFBP-1 concentrations might further reduce the availability of maternal IGF-I to the placenta. This could worsen placental function and so adversely affect fetal growth.
Holmes
R P
RP
Fetal Medicine Research Unit, University of Bristol, St Michael's Hospital, Southwell Street, Bristol BS2 8EG, UK.
Holly
J M
JM
Soothill
P W
PW
D000328:Adult; D015992:Body Mass Index; D005314:Embryonic and Fetal Development; D005260:Female; D005317:Fetal Growth Retardation / Q000209:etiology*; D005865:Gestational Age; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007328:Insulin / Q000378:metabolism*; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000378:metabolism*; D008137:Longitudinal Studies; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D011446:Prospective Studies; D012044:Regression Analysis
D007328:Insulin; D018970:Insulin-Like Growth Factor Binding Protein 1