Genetic testing of embryo seen safe for offspring

NEW YORK, June 23 (Reuters) A new study provides ''reassuring'' evidence that babies born from in vitro fertilization with preimplantation genetic diagnosis (PGD) - in which a cell or two are removed from the developing embryo to screen for genetic problems - are not at increased risk of birth defects.

However, the rate of stillbirth and early neonatal death in PGD pregnancies was higher than would have been expected among children conceived through in vitro fertilization who didn't undergo PGD, or among infants conceived naturally.

''For me it's reassuring, but I think we have to continue with this follow-up, specifically with regard to the stillbirth rate,'' Dr. Ingeborg Liebaers of the Research Centre for Reproductive Genetics at the Free University of Brussels in Belgium, the study's author, told Reuters Health.

Liebaers presented the findings, on 583 births at the center after PGD of the embryo, this month at the European Society of Human Genetics' annual meeting in Nice, France. The study is the first, Liebaers said, to look at a large group of children treated at a single center, although she said there have been follow-up reports from multiple centers that also produced ''reassuring'' results.

Couples who are at risk of certain genetic defects may choose to undergo assisted reproduction with PGD. In the procedure, a single sperm is injected into an egg (a technique called intracytoplasmic sperm injection, or ICSI) and then a cell or two is removed from the developing embryo to check for genetic problems. Embryos that are free of known defects are then transferred to the uterus.

Concerns have been raised that children born after PGD would face a higher risk of malformation, given that the procedure involves removing cells from an embryo, Liebaers noted in an interview.

However, the rate of malformations found in the group in the current study - 3.6% - was no higher than among children born after IVF who did not undergo PGD.

However, 20 of the PGD babies were stillborn and nine died as newborns, a rate higher than that seen after IVF and ICSI without PGD. The risk was particularly high for multiple births, with 23 of the 29 deaths occurring in multiple pregnancies.

Liebaers and her colleagues are performing additional studies to attempt to identify the cause of the higher death rate, and are also following the live born PGD infants to see if they remain healthy and develop normally.

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