When it comes to making babies, the better the sex the better the chances of conception, according to new research. There is a direct link between the quality of a woman's sexual response and the number of sperm available to cause a pregnancy, according to work by Dr Jacky Boivin of Cardiff University's School of Psychology.
The results will be presented later today at the British Association meeting in Cardiff.
But the study is quick to point out that bad sex should not be considered a wise form of contraception.
Nor does having tremendous sex guarantee babies by the dozen. Countless surveys - including the Kinsey report, Masters and Johnson and Shere Hite - all showed that generations of mothers had never experienced orgasm yet had managed to get pregnant.
The research describes her complex analysis of female orgasm increased the number of sperm taken up in the mucus present in the cervix.
She selected women in their mid-30s who had been trying to conceive for over two years.
She eliminated couples with any other apparent reason for failing to conceive, for example abnormal sperm.
She used conventional fertility tests to count the availability of sperm but included a detailed questionnaire which assessed the "woman's subjective evaluation of the encounter".
Her results are striking, leaving little doubt that the more fun the better the chances of conception.
Almost half the women who reported a low sexual response had no sperm in the cervical mucus compared with only one in 10 of women in the high sexual response group.
"In other words, the study results showed a direct correlation between these two variables."
Presence of sperm in the cervical mucus brings no certainty of pregnancy but if none is present then there will be no baby. Even so these women can still sometimes conceive so there are no absolutes.