Religion and science don't normally make for happy bedfellows, especially when it comes to sex. But now, it seems, they're in total agreement. A study into the effects of having sex before marriage suggests it's much better not to. Those who abstain during their courtship or build up a gradual sexual relationship, rather than leaping into bed on the first date, are more likely to have happier and longer relationships.

The researchers who carried out the study, the first of its kind, say that early sexual satisfaction may stunt the development of other key ingredients of healthy relationships, such as commitment, caring, understanding and shared values. "Precocious premarital sexual activities may have lasting effects on relationship quality," they say. "Courtship is a time for exploration and decision-making about the relationship, when partners assess compatibility, make commitments and build on emotional and physical intimacy."

Almost 50 years since the sexual revolution, which began, according to Philip Larkin, in 1963, the evidence suggests an open-legs policy is not so rewarding after all. "The postponement of sexual involvement is associated with higher levels of relationship quality," say the researchers from Cornell University. "Women who deferred sexual involvement for over six months reported significantly higher levels of relationship satisfaction, commitment, intimacy and emotional support, as well as sexual satisfaction with their partner, than did those who became sexually involved within the first month."

In the research, being reported in the latest Journal of Marriage and Family, the researchers analysed data from 600 couples about their relationships. In each case, the woman was aged under 45. Results show that for one in three men and women, sexual involvement took place within the first month, while about 28 per cent waited more than six months.

Most of the couples cohabited before marriage, with 40 per cent marrying directly. More than half the women who married directly had deferred sexual involvement for longer than six months, compared with only 6.5 per cent of women who were cohabiting. The couples were also asked about the quality of their relationships, including giving scores for commitment, intimacy, sexual satisfaction, communication and conflict. Results show that for women, all the scores were better if sex was delayed for one month. A similar trend was found for men, but the differences were not so great.