Researchers expect the male birth control 'pill' will, in fact, be a combination of regular injections and implants rather than a daily tablet because of the difficulties of getting hormones to work reliably in men when taken orally.

Researchers said Friday that a drug could be available within five years if trials being carried out by pharmaceutical companies continue to prove successful.

They predict that it will, in fact, be a combination of regular injections and implants rather than a daily tablet because of the difficulties of getting hormones to work reliably in men when taken orally.

Sperm Count Recovery

The study on sperm counts, which looked at results for 1,500 men, is published in The Lancet.

Researchers headed by Dr. Peter Liu, who works at Sydney University, looked at men taking part in 30 studies between 1990 and 2005. Their sperm output was monitored every month until recovery after they stopped hormone treatment.

The average time taken to recover to 20 million sperm per milliliter of ejaculate, a level that would normally be considered fertile, was 3.4 months.

Five to Eight Years

Professor Fred Wu, of Manchester University, a researcher for a phase II trial on a male "Pill" that has just been completed in Europe, said its findings would be released later this year.

"If the trial is a success we will move to phase III, meaning that male hormonal contraception could come to market in five to eight years' time," he said.

"We are all enthusiastic about this and encouraged by The Lancet results," he added, "which should be very reassuring for men considering this form of contraception."