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Biology Articles » Developmental Biology » Babies Born After Freeze-Thawing Embryos Do Just As Well Regardless Of Whether They Were Created Via ICSI Or Standard IVF
Analysis of the longest running ICSI programme in the United States has
found reassuring evidence that babies born from frozen embryos
fertilised via ICSI (intracytoplasmic sperm injection) do just as well
as those born from frozen embryos fertilised via standard IVF treatment.
The researchers also compared babies born as a result of cycles in
which the women had additional hormone medication with babies born as a
result of unmedicated, natural cycles, and, although they found a
slightly higher rate of malformations in babies born from medicated
cycles, the difference was small – 2.2% versus 0.4%.
Ms Queenie Neri, a research associate at Cornell University (New
York, USA) and a member of the team headed by Professor Gianpiero
Palermo who pioneered ICSI in 1992, told the 25th annual meeting of the
European Society of Human Reproduction and Embryology in Amsterdam today
(Monday) that she and her colleagues had looked at all births from
frozen embryos, conceived via ICSI or IVF, between 1993 and 2007.
Ms Neri identified 720 IVF and 1231 ICSI frozen embryo transfers. The
survival rate of the frozen embryos was 74% after IVF and 77.2% after
ICSI. The clinical pregnancy rate was 42.8% after IVF and 39.4% after
ICSI. These resulted in 84.1% IVF and 89.7% ICSI deliveries. There were
27.8% multiple IVF pregnancies and 21.1% multiple ICSI pregnancies.
Outcomes at the time of birth for Apgar scores, gestational ages, birth
weights and congenital malformations were similar for both IVF and ICSI
When she grouped the babies according to whether they came from
medicated or unmedicated cycles, she found that the clinical pregnancy
rate was 42.1% and 39.4% respectively; delivery rates were 86.7% (with
28.7% multiple births) and 87.5% (19.2% multiple births) respectively.
Gestational ages and birth weights were similar between the two groups,
but the malformation rate was 2.2% from the medicated cycles and 0.4%
from the natural cycles.
Ms Neri said: “Freezing embryos as part of fertility treatment has
become a fundamental part of assisted reproduction technology. We found
no differences in the ability of embryo generated by IVF or ICSI to
implant, even after undergoing the stress of cryopreservation. We were
unable to confirm a significant benefit of the unmedicated cycle on the
neonatal outcome of the cryopreserved embryos; the difference in
malformation rates was small.
“The original premise of the study was to identify a difference in
neonatal outcome while in the presence or absence of infertility
medication, with the assumption that the unmedicated cycles would
generate better offspring outcomes. Interestingly, we did not see any
clear difference in neonatal outcomes between the medicated and
unmedicated groups. From our study, the combination of exposure to
cryopreservation and medications or both did not significantly impair
The malformations ranged from heart defects to defects caused by
hereditary factors and sporadic genetic mutations or interactions.
However, Ms Neri said: “They were within the spectrum of malformations
observed in newborns in the general population.”
As there was no statistical difference between the medicated and
unmedicated cycles, Ms Neri said that it was not possible to say that
medicated cycles were associated with higher rates of malformations, or,
if they were, what mechanism might be responsible.
“Our study reported none of the specific abnormalities linked to male
factor infertility, medications or other environmental triggers such as
extended in vitro culture, which have been reported by other studies,”
“When you think about it, the reproductive medical field has created a
new sub-population. These children are now reaching puberty and their
fertility status still remains to be assessed. Therefore, the continuous
monitoring of children generated through artificial conception is of
paramount importance,” she concluded.
Abstract no: O-062 was presented June 29,2009.
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