Kivonat:
BACKGROUND: Maternal trisomy 21 ovarian mosaicism might provide
the major causative factor for fetal Down syndrome. The small
proportion of trisomy 21 oocytes thought to be retarded in their
maturation in comparison to normal disomic ones, and the
maternal age effect can be based on an accumulation of trisomy
21 oocytes in the ovarian reserve. By lowering the number of
unnecessary ovulations, a greater portion of disomic oocytes
might be saved. STUDY DESIGN: Between September 2009 and
September 2011, we performed genetic amniocentesis for fetal
chromosomal analysis in 5222 pregnancies. We detected 119
structural or numerical chromosomal abnormalities. We collected
data from 37 cases who were in advanced maternal age and where
fetal trisomy 21, 18 or 13 was confirmed. We had 92 control
patients. Detailed information was taken from those factors that
influence the number of ovulations in reproductive life.
RESULTS: From the factors checked, patients with a trisomic
fetus had a shorter overall mean length of oral contraceptive
pill use before the trisomic pregnancy (3.4 vs. 6.0 years,
p<.0014), and the estimated number of mean ovulations was higher
(274.6 vs. 224, p<.0003). CONCLUSION: We found that a history
of longer oral contraceptive pill use and fewer ovulatory cycles
were associated with fewer common trisomies of the fetus.
Additional research is needed to rule out potential confounding
factors, but our results are consistent with the maternal
ovarian mosaicism causal model.
