Trade-off between gestational age and miscarriage risk of prenatal testing: does it vary according to genetic risk?

It has been generally assumed that as genetic risk rises, so the higher procedure-related miscarriage rates of diagnostic tests done earlier in gestation become more acceptable. To test the hypothesis a decision tree was used, in which the only differences between two tests A and B were that A was carried out earlier in pregnancy and was more likely to cause miscarriage. Over a wide range of rankings for the three outcomes (procedure-related miscarriage of a normal baby, early termination of pregnancy after test A, late termination of pregnancy after test B), the expected utility (relative desirability) of an earlier, but more risky, test was greater at a high (1 in 4) than at a low (1 in 100) genetic risk.