WWW- Good news from the sexual front lines: Three-quarters of American women say they’re satisfied with their sex life.

The authors of a new book, “Secrets of the Sexually Satisfied Woman,” surveyed 2,604 women aged 18 to 71 of various backgrounds, income groups and marital status over three months in 2003 on sexual issues ranging from size (and, yes, it does matter) and masturbation to premarital sex and porn.

Among the strongest findings of Drs. Jennifer Berman and Laura Berman was that 80 percent of the women, whether sexually satisfied or not, believe sex should not take place without love, while 87 percent said infidelity was always wrong.

But nearly 40 percent thought sex outside of marriage was fine, while 36 percent thought it was always or nearly always wrong.

Age proved to be a factor in areas beyond general satisfaction, with older women less likely to buy sex-related materials or engage in such variants as oral or anal sex.

Masturbation got a thumbs up overall, with a slight majority (51 percent) partaking in self-gratification. Of those, 41 percent said they only did it while alone, while 7 percent only did it with a partner.

Addressing a question for the ages, the researchers, who are professors at Northwestern and UCLA Medical Center, found that size does indeed matter. Women said they were likelier to be satisfied when their partner has a large penis, with the caveat that a bigger penis does not make a man more masculine.

And speaking of myths, the respondents said they really do want to have orgasms.