Winning a first kiss is enough of a challenge for most male suitors.But getting the act itself right may be even more important - because apparently it can determine whether a relationship blooms.According to scientists, women often judge men on the quality of the first kiss.

The pressure to perform, they say, rests mainly with men, because women have developed kissing as an evolutionary tool to find their Mr. Rights.

The research into the psychology of kissing uncovered a "complicated exchange of information" during a kiss.

Tongue contact and the exchange of saliva were found to help both sexes make subconscious assessments about each other. Women’s breath can indicate hormone levels and fertility, while male saliva will have traces of the sex hormone testosterone.

Bad breath, as well as being unpleasant, can be interpreted by would-be lovers as a sign of health problems.

Researchers at New York’s University at Albany questioned 1,000 students about their views on kissing.

The study, published in the journal Evolutionary Psychology, found that women "place more emphasis on a kiss and are more reliant on kissing as a mate assessment technique" than men.

Most women said that kissing was so integral to an intimate relationship that they wouldn’t contemplate sex without it.

Psychologist Gordon Gallup, who led the study, said: "While many forces lead two people to connect romantically, the kiss - particularly the first one - can be a deal-breaker