Table 3.

The distribution of number of observed rounds of screening, age at first mammogram, and family history of breast cancer at the time of the first mammogram for 143,025 women along with the proportion of women within each category with a false-positive mammography result at their first mammogram.

	N	%	% false-positive at first exam
Number of screening rounds observed
1	71,440	49.9	17.2
2	28,500	19.9	16.3
3	16,584	11.6	16.8
4	10,552	7.4	15.7
5	6,889	4.8	16.1
> 5	9,060	6.3	13.9
Age at first exam
40–41 years	55,145	38.6	15.8
42–43 years	24,005	16.8	16.3
44–45 years	15,358	10.7	17.3
46–47 years	11,406	8.0	17.4
48–49 years	9,080	6.3	18.3
50–51 years	9,184	6.4	18.4
52–53 years	6,355	4.4	17.9
54–55 years	4,893	3.4	17.8
56–57 years	4,041	2.8	15.4
58–59 years	3,558	2.5	15.5
Family history at first exam
No	133,771	93.5	16.5
Yes	9,254	6.5	18.6