A daily contraceptive gel for men which is applied to the shoulders has shown promise in early trials.
The product, which is rubbed on both shoulder blades daily, has been found to lower sperm counts in around eight weeks.
Scientists say this is quicker than other similar products in development and could overcome a limitation of other male hormonal contraceptives.
The product contains two hormones, Nestorone (segesterone acetate) and testosterone, and is currently being tested as part of a clinical trial on more than 200 men in the US.
The gel is rubbed into the shoulders or shoulder blades because it is easy to reach for the user and it is also unlikely a child or woman would come into direct contact with the gel in this location.
The hormones soak into the skin and are absorbed by the bloodstream and accidental exposure to the gel could cause premature puberty in children and acne or excessive hair growth in women.
Phase two results announced on Sunday at the Annual Conference of The Endocrine Society in Boston, US, reveal the product reached low sperm levels in 80 per cent of men after just 12 weeks.