Hum. Reprod. Advance Access originally published online on July 8, 2005
Human Reproduction 2005 20(11):3152-3156; doi:10.1093/humrep/dei165
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Cell-free fetal DNA levels in pregnancies conceived by IVF
1 Division of Genetics, Departments of Pediatrics and Obstetrics and Gynecology, Tufts-New England Medical Center, 750 Washington Street, Box 394, Boston, MA 02111, 2 Institute of Clinical Research and Health Policy Studies, Tufts-New England Medical Center, Boston, MA 02111 and 3 Division of Prenatal and Special Testing, Department of Pathology, Women and Infants’ Hospital, Brown Medical School, Providence, RI 02903, USA
4 To whom correspondence should be addressed. E-mail: kjohnson{at}tufts-nemc.org
BACKGROUND: Increased second-trimester levels of maternal serum HCG in IVF conceptions lead to an increased false-positive rate in Down syndrome screening. Increased levels of cell-free fetal DNA (cffDNA) in maternal plasma have been correlated with increased HCG levels. Our aim was to determine whether cffDNA levels are elevated in IVF pregnancies compared with natural pregnancies. METHODS: Sixteen archived second-trimester serum samples from IVF pregnancies were matched with five control samples from naturally conceived pregnancies per case, all carrying a singleton male fetus. cffDNA concentrations were measured by real-time PCR amplification of a Y chromosome sequence and compared with four standard second trimester serum screening markers (
-fetoprotein, estriol, HCG and inhibin A). RESULTS: Mean cffDNA levels for cases and controls were 57.9 and 57.1 genome equivalents/ml, respectively (P = 0.95). Mean observed rank (from 1 to 6) of cffDNA was 3.625 in the IVF conceived group, compared with an expected value of 3.5 (P = 0.53). No significant correlations were observed between cffDNA and serum markers. CONCLUSIONS: IVF does not affect levels of cffDNA, which appears to be independent of traditional screening markers (e.g. HCG). Therefore, cffDNA can be used as an additional serum marker (e.g. Down syndrome screening) without adjustment for IVF pregnancies.
Key words: DNA/IVF/pregnancy/prenatal diagnosis/serum screening markers