Cell-free fetal DNA levels in maternal plasma after elective first-trimester termination of pregnancy.

Objective: To determine if first-trimester elective termination of pregnancy affects cell-free fetal DNA (fDNA) levels in maternal plasma.

Design: Prospective cohort study.

Setting: Clinical and academic research centers.

Patient(s): One hundred thirty-four women who underwent first-trimester elective termination procedures.

Intervention(s): None.

Main Outcome Measure(s): Real-time polymerase chain reaction (PCR) amplification and measurement of DYS1, a Y-chromosome sequence, was used as a marker of fDNA.

Result(s): We detected fDNA in pretermination samples from 27 out of 71 patients in the surgical arm, and 29 out of 63 patients in the medical arm. Based on confirmation of male gender in placental tissue, the sensitivity of fDNA detection is 92.6%. We detected fDNA as early as 32 days of gestation, which increased 4.2 genome equivalents/mL/week. In the surgical arm, the mean level of posttermination fDNA, adjusted for the clearance of fDNA in maternal blood, was higher than projected based on an expected increase with gestational age. In the medical arm, six patients had increased fDNA levels up to 11 days following termination.

Conclusion(s): We found that fDNA can be reliably quantified in the early first trimester; fDNA elevation that occurs shortly after surgical termination may reflect fetomaternal hemorrhage or destruction of trophoblastic villi. Continued elevation of fDNA for several days may occur following medical termination.