What’s the News: What if the egg is fine and the sperm is dandy, but you still can’t seem to have a baby? Couples who are having trouble conceiving can testify to the frustration of learning that there’s no clear reason for their infertility. Now, however, scientists have found a genetic mutation that makes outwardly normal sperm much less fertile, potentially explaining many such cases and suggesting new routes to conception.

What’s the Context:

Infertility is defined as failure to conceive after a year of unprotected sex. About 10-15% of couples run into this problem.
Some cases of infertility are fairly easily explained: there may be a shortage of sperm, or they may be unable to swim far enough to make it to the egg. The eggs in turn may be malformed, or the womb may have conditions that make implantation of the fertilized egg difficult. But in about 20% of infertile couples, it’s not clear what is impeding the process.
When treating infertility, knowing the source of the problem is a big help. For instance, if the problem is the number of sperm, one option is concentrating sperm into a single sample and trying with ...