Women affected by common side-effects associated with the Pill could soon be offered an alternative form of contraception.
Experts are hoping that a new clear gel that administers anti-pregnancy hormones will continue to show positive clinical trial results.
Women using the gel, which is applied daily to the abdomen, thighs, arms or shoulders, have reported none of the typical side-effects of the Pill, such as weight gain and acne.
It is also suitable for women who are breastfeeding, who are often warned not to take the combined Pill because its hormone levels interfere with milk supply.
Dr Ruth Merkatz, Director of Clinical Development of Reproductive Health at the not-for-profit Population Council research centre in New York, led the latest study on the gel, which involved 18 women in their 20s to 30s.
Over the course of seven months, none of the women fell pregnant and the gel had "very high acceptability", she said.
The research found the optimum dose was the small amount of 3mg a day.
Dr Merkatz, who is presenting the findings at the American Society for Reproductive Medicine (ASRM), said the gel could enhance the choices women have
The key drug in the gel is Nestorone, a new type of progesterone. The product also contains a type of oestrogen that is chemically identical to the oestrogen produced by a woman's body.
Both these hormones play an important role in pregnancy and the gel works by interfering with their normal patterns of production.
Dr Merkatz said Nestorone does not appear to have any of negative effects seen in oral contraceptives, such as weight gain.
"This could be a reason why women might choose it," she said.
"Would be a great alternative to what is available, probably better for people in long-term relationships as youngsters may forget to use the gel. How would/could showering interfere with the product?" - Julie Wyer, S. Wales
"Would this gel also alleviate the symptoms of heavy flow, severe pain and mood swings?" - Diane, US