Insulin-like growth factor binding protein 1 level in amniotic fluid: correlation with birth weight.

Insulin-like growth factor binding protein 1 is the predominant insulin-like growth factor binding protein in amniotic fluid. It is produced by the decidua and by fetal tissues, and it is thought to play an important role in fetal growth. We have measured this protein in 58 samples of amniotic fluid, from 13 to 19 gestational weeks, and found a highly significant negative correlation with fetal weight at birth. We conclude that the level of insulin-like growth factor binding protein 1 in amniotic fluid at midpregnancy is a good marker of fetal growth failure.