The women were given 200 milligrams of guaifenesin three times a day, from the fifth day of menstruation through to ovulation. Dr. Check found that 23 of the women showed "marked improvement in postcoital tests after treatment, while seven showed slight improvement," meaning that their cervical mucus was noticeably thinner.
More important, of those 23 couples, Dr. Check wrote that 15 became pregnant while testing the regimen. One patient with only mild improvement in her mucus levels also conceived. Dr. Check concluded that guaifenesin is "one of the simplest and cheapest treatment methods of addressing the cervical factor."
You might expect such a declaration to produce an instantaneous ad campaign showing beaming women sipping cough syrup and rubbing their bellies, swollen with child.
But in nearly 30 years since his initial experiment, Dr. Check's study has been met with silence, both within the scientific community and from pharmaceutical companies that make the product.
Pfizer Canada, which manufactures Robitussin here, would not comment on its reputation as a fertility aid.
Caroline Hey, the communications manager for Reckitt Benckiser Group PLC, which makes the U.S. equivalent, Mucinex, said the product should be used only according to package directions.
"We do not have any data for the use of Mucinex for fertility issues nor do we recommend its use for this purpose," she said in an e-mail.
The medical disconnect
The lack of data on Robitussin's off-label reputation is surprising in an era when everything from road rage to sleep apnea has been the subject of scientific study, and in a market where antidepressants have been repackaged as smoking-cessation tools and birth control is used as acne medication.
But when it comes to fertility, in-vitro fertilization appears to have become the first and final word for women attempting to conceive.
Anthony Cheung, a reproductive endocrinologist and medical director of the in-vitro fertilization program at the University of British Columbia's Centre for Reproductive Health, is familiar with the theories surrounding Robitussin, but he believes they're esoteric in the grand scheme of fertility issues. "If it was that easy, I would think couples really wouldn't need anything," he said. "I think it's interesting and I don't think we should write it off completely, but like all things, it should go through the same trials to prove or disprove it."
And therein lies the problem, he said. Since the 1980s, postcoital investigations of fertility issues have lost favour as scientific standards have become more rigorous. There is really no way to standardize what is "normal" when it comes to conception. How much mucus is too much? How thin does it need to be for sperm to get through? The answers could be different for every couple.
If you have a tubal problem, or an infection, or a different type of hormone imbalance, this is not going to help you get pregnant. Colette Bouchez, medical journalist
So the medical community has moved on, propelled by advances in technology that have seen in-vitro fertilization become standard treatment for fertility problems. "Cervical mucus can be overcome by doing insemination, so it doesn't even matter," Dr. Cheung said of Robitussin's possible effect.
But women prefer to conceive naturally, and the rapid push toward medical intervention can be unsettling.
When Meghan O'Brian began asking doctors about her inability to conceive, she was quickly directed toward more invasive, expensive procedures such as hormone therapy and in-vitro insemination, even though tests showed no obvious barriers to natural conception. When she questioned the need to take such a big step at her age, she was told by one doctor not to come back until she was serious about getting pregnant. When her sister told her about Robitussin, she and her husband decided to give it a try. "It just seems like such an easy first step," she said. "In our case, it was like, 'Why not?'"
For Jennifer, a 40-year-old Toronto security specialist and mother of two, hearing that someone had a positive experience with Robitussin means more than any study or clinical trial. She and her husband are trying for a third child, and their age makes it unlikely that they will conceive without considerable luck and effort.