Table 1.

Indication for testing, overall and by testing year.

Indication	Year 1	Year 2	Year 3	Overall	Positivity rate
Maternal age	52.9%	54.1%	52.5%	52.9%	3.9%
Ultrasound findings	22.0%	16.7%	12.0%	16.7%	12.5%
No known high-risk indication	3.0%	7.2%	16.6%	9.0%	2.3%
Multiple indications	7.9%	8.1%	6.3%	7.8%	9.1%
Personal/family history	5.8%	5.2%	3.9%	4.9%	3.1%
Serum biochemical screening	5.7%	4.6%	4.0%	4.7%	4.6%
Other high-risk indication	2.9%	4.1%	4.8%	4.0%	2.2%

The right-most column shows the positivity rate for each indication.