Figures & data
Table 1. Characteristics of 2906 pregnancies redrawn after an initial sample with insufficient fetal fraction.
Figure 1. Distribution of maternal weight and gestational age at the time of first and second draws. Maternal weight is at the time of first draw and was available for 2466 pregnancies.
Table 2. Results of multivariate regression analysis demonstrating the contribution of specific factors to obtaining a result with repeat testing.
Figure 2. Predicted probability of obtaining a result by interval between draws. The interval is given in days and is calculated from the day the initial sample was drawn (not when it was reported). Probabilities are plotted for three maternal weight values: 70, 90, 110 kg.
Table 3. Proportion of results obtained in pregnancies with multiple repeat tests.