Fetal brain to liver weight ratio as a measure of intrauterine growth retardation: analysis of 182 stillborn autopsies.

The fetal brain/liver weight ratio of 182 stillborn fetuses was analyzed for its value as a measure of intrauterine growth retardation. The ratio was evaluated as a test for the detection of small-for-gestational age fetuses, compared with the ponderal index, and evaluated for correlation with maternal histories that were compatible with fetal growth retardation. Both brain/liver ratio and ponderal index were insensitive and relatively nonspecific indicators of low fetal body weight in this population. Brain/liver weight ratio was considerably more sensitive in those cases that were at least 20 weeks of gestational age, and specificity increased as the cut-off point was increased above 3. Those cases with maternal history or placental findings compatible with asymmetrical-type intrauterine growth retardation were statistically more likely to have elevated brain/liver weight ratios and depressed ponderal indices, but there was considerable overlap among cases with different disease types. Prosectors of fetal autopsies must make use of all the information available to them. The fetal brain/liver weight ratio and the ponderal index may be useful, but they are not satisfactory indicators of intrauterine growth retardation by themselves, and they also may be inadequate for the detection of growth retardation etiology.