LYON, France -- As the complexity of assisted reproduction techniques increases, so does the frequency of umbilical cord abnormalities, Belgian investigators reported here.
LYON, France, July 5 -- As the complexity of assisted reproduction techniques increases, so does the frequency of umbilical cord abnormalities, Belgian investigators reported here.
Compared with spontaneous conception, in vitro fertilization doubled the risk of velamentous insertion, or cord attachment to the placental membrane (7.4% versus 3.6%), Ilse Delbaere, of the University of Ghent, and colleagues, reported at the European Society of Human Reproduction and Embryology meeting.
Use of intracytoplasmic sperm injection (ICSI) tripled the likelihood of velamentous insertion to 10.4% compared with spontaneous conception, she added.
The comparison of outcomes in more than 4,000 sets of twins conceived spontaneously or by assisted reproduction techniques also showed that artificial induction of ovulation triples the likelihood of a single-artery umbilical cord (1.9% versus 0.6%).
"This is not the type of research that will change a lot in terms of procedures, but we thought it was important to report our findings because we know that that the birth rate for singletons and twins after IVF and ICSI is a little lower than for spontaneously conceived singletons and twins," Delbaere said.
"Physicians who apply assisted reproduction techniques are not only interested in achieving pregnancies but they also want to guard the quality of the procedures," she added. "They are always interested in knowing more about why the birth rates are lower."
As a fetus develops, umbilical cord insertion near the center of the placenta portends a more favorable outcome, Delbaere noted. Cord insertion toward the edge of the placenta or on the placental membrane increases the likelihood of preterm delivery, low birth weight, and other perinatal complications. In addition, development of a single umbilical artery correlates with other anomalies and an increased mortality risk.
The association between mode of conception and cord abnormalities has been investigated but only in studies involving small numbers of patients. The association between assisted reproduction techniques and single-artery umbilical cord had not been studied previously, according to the investigators.
Data from the East Flanders Prospective Twin Survey (EFPTS) afforded an opportunity to examine the association between conception and umbilical cord abnormalities in a large population of multiple births. Since 1964 all multiple births in the East Flanders province of Belgium have been registered in the EFPTS. A trained midwife collects and examines the placenta in a standardized manner within 48 hours of delivery. Zygosity and chronicity also are determined by sequential analysis of sex, fetal membranes, and biochemical markers.
Delbaere and colleagues reviewed data on 2,119 spontaneously conceived dizygotic twins and 2,243 dizygotic twins conceived by assisted reproduction. Marginal cord insertion, velamentous cord insertion, and single-artery cord occurred significantly more often with ART (P<0.001).
Separate analysis of each type of anomaly revealed an increased risk in association with assisted reproduction techniques (P<0.001). Artificial induction of ovulation was associated with a lower rate of velamentous cord insertion compared with IVF and ICSI but still significantly higher than with spontaneous conception (5% versus 3.6%, P<0.001).
The data could not shed light on the precise causes of umbilical cord abnormalities related to assisted reproduction. However, the investigators speculated that during some cases of assisted reproduction an embryo might be transferred to a poorly nourished area, and the placenta might migrate to an area affording more favorable conditions for growth and development. Under those circumstances, an initially central cord insertion might evolve into a more peripheral insertion.
Commenting on the potential implications of the findings, Ertug Kovanci, M.D., of Baylor College of Medicine in Houston said, "This group did not correlate the findings with pregnancy outcome, so it is hard to evaluate how this information might be used. I don't see these results changing clinical practice in any way."