Cell-free fetal DNA levels in pregnancies conceived by IVF.
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 (alpha-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.
Pan
Phillip D
PD
Division of Genetics, Department of Pediatricsogy, Tufts-New England Medical Center, 750 Washington Street, Box 394, Boston, MA 02111, USA.
Peter
Inga
I
Lambert-Messerlian
Geralyn M
GM
Canick
Jacob A
JA
Bianchi
Diana W
DW
Johnson
Kirby L
KL
D015415:Biomarkers / Q000097:blood; D006063:Chorionic Gonadotropin / Q000097:blood; D004247:DNA / Q000097:blood*; D004314:Down Syndrome / Q000097:blood* / Q000175:diagnosis*; D004964:Estriol / Q000652:urine; D005189:False Positive Reactions; D005260:Female; D005307:Fertilization in Vitro; D005315:Fetal Diseases / Q000097:blood / Q000175:diagnosis*; D005333:Fetus / Q000378:metabolism*; D006801:Humans; D008297:Male; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D000509:alpha-Fetoproteins / Q000032:analysis
D015415:Biomarkers; D006063:Chorionic Gonadotropin; D000509:alpha-Fetoproteins; D004247:DNA; D004964:Estriol