A popular IVF technique may alter the natural gender ratio, American researchers have found. A survey of babies created with intracytoplasmic sperm injection (ICSI) found that normal ratio of 105 boys to 100 girls is reversed. In the ICSI technique, sperm is injected straight into the egg. The implications of these results are unclear, say the researchers, in an article in the journal Fertility and Sterility. However, they warn that ICSI should be used with caution: "because our findings suggest that ICSI may reduce the sex ratio, we recommend that ICSI only be done if medically necessary, in an effort to prevent this potential side effect." ~ Reuters, Nov 25