A recent study concluded that quality of sperm declines after vasectomy and, by consequence, children born after vasectomy reversal surgery may be at higher risk of birth defects.

Clearly, the finding of this study that post vasectomy reversal sperm has a higher probability of certain abnormalities does not establish for sure that children born after vasectomy reversal will be abnormal.

One possibility is that these observed abnormalities don't produce birth defects.

Another is that the abnormalities detected in some sperm after vas reversal are serious enough that they render that particular sperm infertile, so that any child conceived after vas reversal would be conceived from other sperm.

Another possibility is that some men, for whatever reason, don't develop these abnormalities after vasectomy; or that their sperm returns to normal very quickly after reversal.

Finally, it's possible the study is flawed in some way (perhaps it did not sufficiently control for factors accounting for the observed abnormalities that are not related to the vasectomy) or that it cannot be duplicated by other researchers.

As the report of the study says, this research is only preliminary and more research is necessary. Certainly this is another reason to consider vasectomy a permanent step. And/or to store sperm before vasectomy if you have the slightest suspicion you might want to make babies afterward.