Having sex on the first date doesn't mean there's no hope for a relationship, but it can lead to problems in the long run.

Researchers studied 10,932 unmarried people in steady or serious relationships. The participants were asked to rate their level of satisfaction with their relationship, their ability to communicate with their partner and how stable their relationship was or how often they felt like their relationship was in trouble.

The results showed that couples who had engaged in sex before or within the first few weeks of dating had lower levels of relationship satisfaction, communication and stability after a year compared to couples who waited longer to have sex or who did not have sex.

Researchers noted that the results held true even after accounting for race, education, number of sexual partners and religious attendance.

The latest findings support previous research in married couples that found that the longer couples waited to have sex before marriage, the higher their marital satisfaction.

Scientists are not sure why delaying sex was linked to better relationship outcomes, but they speculate that couples who engage in sex early might have higher expectations for their sex life later on. However, factors that contribute to a "good sex life" such as frequency of sex and partners' interest in sex later on tend to decline over time.

"The eventual mismatch between individual sexual expectations and actual rewards may undermine healthy couple formation processes," the researchers wrote in the study published in the Nov. 2 issue of the Journal of Sex Research.

"Results suggested that waiting to initiate sexual intimacy in unmarried relationships was generally associated with positive outcomes. This effect was strongly moderated by relationship length, with individuals who reported early sexual initiation reporting increasingly lower outcomes in relationships of longer than two years," researchers concluded.