Table 3. Distribution of total samples across trimesters compared to the number and frequency of RATs.
Trimester (weeks)Cohort 1Cohort 2P*
Total cases, n (%)RATs, n (as % of trimester totals)Total cases, n (%)RATs, n (%)
First (10–13)47,829 (65.6)163 (0.34)15,643 (92.6)53 (0.34)1.000
Second (14–27.9)24,133 (33.1)78 (0.32)1,230 (7.3)6 (0.49)0.299
Third (28–40)970 (1.3)5 (0.52)12 (0.1)1 (8.3)0.083
Total72,932 (100)246 (0.34)16,885 (100)60 (0.36)0.122

*Between frequencies of RATs in cohorts 1 and 2.