Ipasaphor

From Memory Alpha, the free Star Trek reference

The ipasaphor is a yellowish mucilaginous substance secreted from the palms and fingers of Ocampa females who have begun the elogium. Appearing very soon after the other signs of elogium (such as the appearance of the mitral sac), the ipasaphor makes the mating bond possible.

With the appearance of the ipasaphor, mating must begin within approximately fifty hours. The female and her mate must remain bonded for six days to ensure conception.

As elogium only occurs once in Ocampa females, it is critical that the rolissisin be performed soon after the appearance of the ipasaphor, and mating soon after. (VOY: "Elogium")