胚胎DNA含量低的原因

Low fetal fraction has been linked to very early gestations, high maternal BMI, maternal medications, smoking and factors which lead to a smaller placenta, such as trisomies 13 and 18 (Kuhlmann-Capek et al. 2019)

The FFs were 8.8% (6.6‐12.1), 8.7% (6.3‐11.6), and 7.7% (5.1‐9.3) among women taking 0, 1, and two or more medications, respectively (P < 0.01). Using mul- tivariable linear mixed effects model, the mean FF was significantly lower among those taking two or more medications compared with the nonexposed group. FF was directly correlated with gestational age at the time of cfDNA testing and inversely correlated with maternal obesity. Exposure to metformin was associated with 1.8% (0.2‐3.4) lower mean FF when compared with the nonexposed group (P = 0.02). Obesity and intake of two or more medications were associated with higher hazard ratio of having a low FF less than 4%.

Exposure to metformin or two or more medications was associated with decreased FF, and obesity is associated with delay in achieving adequate FF per- centage. These findings should be considered while counseling patients on test limitations.