EARLY GROWTH-RETARDATION IN THE 1ST TRIMESTER - IS IT CHARACTERISTIC OF THE CHROMOSOMALLY ABNORMAL FETUS

There have been recent reports on a small number of cases which suggest that the detection of early growth retardation might allow recognition of the chromosomally abnormal fetus in the first trimester of pregnancy. To amplify these observations, the crown-rump length (CRL) measurements between the 64th and 86th day of menstrual age were determined in (a) 500 control high risk patients in whom a normal karyotype was subsequently demonstrated by chorionic villus sampling (CVS) and (b) 25 chromosomally abnormal fetuses. The data indicate that early growth retardation, as expressed by a small CRL measurement, is not a special characteristic of the chromosomally abnormal fetus in the first trimester of pregnancy. The CRL measurement is therefore not a useful marker or screening test at that time, except perhaps for triploidy. The well documented growth retardation with trisomy 21 and trisomy 18 which has been observed in the second trimester does not begin until after the 12th week of menstrual age.