The benefits of sexual closeness during birth

I found this among my research:

“All the normal lovemaking techniques used by husband and wife in coitus also have a beautiful augmenting effect on the progress of labor and birth. Deep, warm kisses relax the mother’s face and the other end of her anatomy, too. Nipple stimulation brings on contractions that are more effective. In addition, coitus in the early stage of labor is very beneficial because seminal plasma contains the hormone relaxin (at high levels, no less) which lengthens pelvic ligaments and softens the cervix. Furthermore, tender touches, husky whispers, sustained eye contact, and body odors each contribute something of value to the climactic orgasm of birth.”
-From “The Benefits of Sexual Closeness During Birth,” by Marilyn Moran (Two Attune, Sept. 1992)