WASHINGTON (AP) — Freezing human eggs can be successful in treating infertility — but guidelines issued Friday still urge caution for women hoping to pause a ticking biological clock.Egg freezing had long been labeled experimental, but the American Society for Reproductive Medicine declared that’s no longer the case. The group cited studies that found younger women are about as likely to get pregnant if they used frozen-and-thawed eggs for their infertility treatment as if they used fresh ones.The move is expected to help cancer patients preserve their fertility, by pushing more insurers to pay for their procedure, and to boost banking of donated eggs, similar to sperm banking.Here’s the controversy: Should otherwise healthy women freeze their eggs as sort of an insurance policy against infertility in case they don’t meet Mr. Right — or just aren’t ready for motherhood — until their late 30s or beyond, when the childbearing window is closing fast?The pricey technology, which insurance doesn’t cover for elective reasons, is being marketed aggressively for just that use.Yet the society that represents doctors who treat infertility stopped short of endorsing egg freezing solely for deferring childbearing until women are older. The conclusion: It’s not at all clear who’s a good candidate, or if women who store their eggs are being given a false sense of security.“The bottom line is there is no guarantee,” said Dr. Samantha Pfeifer of the University of Pennsylvania, who chaired the society’s guideline committee.