TABLE 1.

Usefulness of the IgG avidity test^a for pregnant women whose tests for IgM antibodies yielded positive results in the first trimester of pregnancy^b

Patient no.	Gestation wk	Dye test (IgG) titer	IgM titer	Avidity
73	9	256	Positive	High
58	12	512	Positive	High
17	12	256	Positive	High
74	12	1,024	Positive	High

^aVidas IgG avidity test (Bio Merieux, Lyon, France).

^bThe combination of the high Dye test (IgG) titers and positive IgM test titers would strongly suggest to physicians that these women acquired their infection during gestation. The avidity test results reveal that each of the women was infected prior to the present pregnancy (see text).