Couples considering assisted reproductive technology (ART) techniques such as IVF may be interested in findings from studies presented at the Annual Meeting of the American Society for Reproductive Medicine and the Canadian Fertility and Andrology Society. The studies - one focused on single pregnancies and the other on twins - looked at the risks of chromosomal disorders in pregnancies conceived by women over the age of 35 through ART.
"Prior to our study of singleton pregnancies conceived with ART, there was evidence in the literature showing many of the miscarriages were attributed to genetic abnormalities," said Margareta D. Pisarska, co-director of the Center for Reproductive Medicine at Cedars-Sinai. "We wanted to investigate whether these abnormalities were the result of the ART procedure itself or were inherent to the infertility condition which was overcome by ART." ART procedures include in vitro fertilization (IVF), gamete intrafallopian transfer (GIFT) and zygote intrafallopian transfer (ZIFT) which combines IVF and GIFT.
The good news is that the researchers found no reason for concern over the use of ART in singleton pregnancies. "We did not find any higher incidence of cytogenetic abnormalities at this stage, between pregnancies achieved in infertile couples after treatment compared to those of spontaneous pregnancies. Nor did we find any higher rate of abnormalities in couples treated with ART compared to those treated with fertility drugs and insemination. This was very reassuring to us as fertility physicians," remarked Pisarska.
But the news wasn't so good for couples conceiving twins via ART. It seems that a woman who is 38 (the average age of the study participants) who has a singleton pregnancy conceived spontaneously has a 1 in 60 chance of having a child with a chromosomal disorder, but if she has a twin pregnancy, that rate jumps to 1 in 34.
"Previous studies suggested that there was an increased incidence of chromosomal disorders in twins. There was also controversy whether there was an increased risk of genetic abnormalities in pregnancies conceived through IVF. We wanted to determine if both factors were independent risk factors and if there was an increased risk of chromosomal abnormalities among twin gestations conceived through IVF," Pisarska explains. "We wanted to see if IVF treatment adds to the rate of chromosomal abnormalities in twins, and we found that it did. However, age was an important factor. Even though the age difference in the women who conceived with the help of IVF compared to those who conceived spontaneously was not very large - 39 versus 37 - it was significant enough to say that age may be a contributing factor. We need to look at this further."
Pisarska said that genetic screening could help identify any potential problems, especially for women over 35. "We strongly encourage women over the age of 35 who come to us for fertility treatment to undergo perinatal diagnostic testing such as chorionic villus sampling or amniocentesis. Early cytogenetic testing gives couples the opportunity to consider their options early if a pregnancy is genetically abnormal," she concluded.
Source: Cedars-Sinai Medical Center