BACKGROUND: Cell-free DNA screen failure or "no calls" occur in 1-12% of samples and is frustrating for both clinician and @entity1 . The rate of no call has been shown to have an inverse relationship with gestational age. Recent studies have shown an increased risk for no calls among @entity28 @entity1 . OBJECTIVE: We sought to determine the optimal gestational age for cell-free DNA among @entity28 @entity1 . STUDY DESIGN: We performed a retrospective cohort study of @entity1 who underwent cell-free DNA at a single tertiary care center from 2011 through 2016. Adjusted odds ratios with 95% confidence intervals for a no call were determined for each weight class and for each weight class compared to normal-weight @entity1 . The predicted probability of a no call with 95% confidence intervals were determined for each week of gestation for normal-weight and @entity28 @entity1 and compared. RESULTS: Among 2385 @entity1 meeting inclusion criteria, 105 (4.4%) had a no call. Compared to normal-weight @entity1 , the adjusted odds ratio of a no call increased with increasing weight class from overweight to @entity28 class III (respectively: adjusted odds ratio, 2.31; 95% confidence interval, 1.21-4.42 to adjusted odds ratio, 8.55; 95% confidence interval, 4.16-17.56). A cut point at 21 weeks was identified for @entity28 class II/III @entity1 at which there is no longer a significant difference in the probability of a no call for @entity28 @entity1 compared to normal-weight @entity1 . From 8-16 weeks, there is a 4.5% reduction in the probability of a no call for  @entity28 class II/III @entity1 (respectively: 14.9%; 95% confidence interval, 8.95-20.78 and 10.4%; 95% confidence interval, 7.20-13.61; Ptrend < .01). CONCLUSION: The cut point of 21 weeks for optimal sampling of cell-free DNA limits reproductive choices. However, a progressive fall in the probability of a no call with advancing gestational age suggests that delaying cell-free DNA for @entity28 @entity1 is a reasonable strategy to reduce the probability of a no call.

XXXX and cell-free DNA "no calls": is there an optimal gestational age at time of sampling?

@entity1 :: ('9606', 'Species') :: ['women', 'patients', 'patient'] @entity28 :: ('MESH:D009765', 'Disease') :: ['obese', 'obesity']
@entity28 :: (MESH:D009765,Disease) :: ['Obesity']
