Optimizing Natural Fertility.
Fertility & Sterility. 2008 Nov;90(Suppl 3):S1-S6
Practice Committee of the American Society for Reproductive Medicine in collaboration with the Society for Reproductive Endocrinology and Infertility
This consensus Practice Guideline for physicians suggests recommendations for patients to increase the chances of conception in normal healthy couples. Physicians are reminded that some vaginal lubricants may decrease fertility, based on their observed effects on sperm survival in vitro. A lubricant "such as Pre-Seed" with "no demonstrable adverse impact on semen parameters" is suggested for these patients.
See a summary of these ASRM Guidelines.