The use of in vitro fertilization (IVF) or another assisted fertility technique called intracytoplasmic sperm injection (ICSI) to conceive appears to increase the odds of Y-chromosome defects or "microdeletions" in male offspring, Chinese researchers report. Such deletions could result in defective sperm production and possibly also hypospadias -- a common birth defect of the penis that occurs when the urinary outlet develops on the underside of the penis rather than at the tip.
Although this study was small, it "at least sounds an alarm about the genetic safety of assisted reproductive technology," the investigators conclude. Prior research has tied assisted reproductive technologies with low birth weight, preterm delivery, cerebral palsy, and major birth defects, leading some researchers to hypothesize that these therapies may induce gene mutations.
In the new study, Dr. He-Feng Huang, from Zhejiang University, and colleagues sought to answer this question by testing for genetic mutations in 19 male infants conceived through IVF, 18 conceived through ICSI, and 60 conceived naturally. The fathers of the infants were also tested. In an effort to isolate the impact of the fertility treatment, the researchers only studied infants whose parents had a normal genetic background.
Huang and colleagues found Y-chromosome microdeletions in one infant conceived with IVF (5.3 percent) and in three conceived with ICSI (16.7 percent). By contrast, no Y-chromosome deletions were seen in the control group.
One of the four infants with microdeletions had hypospadias, the report indicates.
This is not the first study to link ICSI with hypospadias, the investigators note, but the mechanism has been unclear. The current findings suggest that the association may be mediated through Y-chromosome microdeletions.
ICSI is the main method used to overcome male infertility. With ICSI, a single sperm is injected directly into a single egg. If successful fertilization occurs, the embryo is then placed into the female to undergo development as usual.
Larger studies "should be conducted to confirm our preliminary results," the researchers conclude.
