Researchers from the Johns Hopkins Children's Center report that a group of rare urological defects, including bladder development outside the body, may be more common in children conceived through in vitro fertilization (IVF). The researchers caution, however, that the findings are preliminary, and should not necessarily dissuade couples from considering the procedure.
Information collected on 78 children with cloacal-bladder exstrophy-epispadias complex treated at the Johns Hopkins Children's Center from 1998 to 2001 shows these birth defects are approximately seven times more widespread in IVF children. An estimated 12 percent to 14 percent of the children born each year with exstrophy-epispadias in the United States are evaluated at the Children's Center. The findings are reported in the April issue of the Journal of Urology.
"What we are seeing now is simply an association between this group of birth defects and IVF births," said the study's senior author, John P. Gearhart, M.D., director of the division of pediatric urology at the Children's Center.
"Further research is needed to verify these findings and understand this association. These defects are extremely rare, and our preliminary findings should not alone discourage couples from undergoing IVF."
Exstrophy-epispadias complex, which is comprised of defects of the bladder, pelvic bones, urethra, and genitals, occurs in approximately four out of every 100,000 live births. Applying this incidence data to the 112,127 children who were born through IVF from 1997 to 2000, researchers determined that approximately five affected children would be expected among the entire U.S. IVF population during this four-year span.
Four of the 78 children with exstrophy-epispadias seen at the Children's Center were conceived using IVF. Comparing this to the expected rate of exstrophy-epispadias among IVF children during the same time period, researchers estimate the incidence of these birth defects are up to 7.3 times more common in the IVF population.
The most common defect of the exstrophy-epispadias complex is bladder exstrophy, a condition in which the bladder is exposed, inside out, and protrudes through the abdominal wall. In addition, the skin on the lower abdomen does not form properly, the pelvic bones are widely spaced, and there may be genital abnormalities.
"With reconstructive surgery, we can close abdominal wall defects, reform the pelvic bones, create normal appearing external genitalia, and help the child gain urinary continence. Following surgery, most children go on to live a normal life with normal bladder and reproductive function," said Gearhart.
Exstrophy-epispadias is four to six times more likely in boys than girls. Researchers believe these birth defects are caused by failed development of the urogenital system during the first trimester of pregnancy.