For about two weeks every month, Jennifer O’Brien (not her real name) takes one tablespoon of Robitussin cough syrup each evening before going to bed. But the 40-year-old mother of two doesn’t have a cough — she’s just trying to get pregnant.
An ingredient called guaifenesin, found in expectorant cough syrups, has gained a reputation as a fertility aid in chat groups, online pregnancy forums and even in best selling pregnancy books. In a time when fertility treatments cost thousands of dollars, it’s not surprising that a $5 solution has intrigued women for more than 20 years. But it is unusual that despite decades of word-of-mouth debate, there’s little scientific evidence to prove that guaifenesin works – or that it doesn’t – leaving it in a strange realm somewhere between old wives’ tale and unsung miracle drug.
O’Brien and her husband are trying for a third child but her age makes it unlikely that they will conceive without considerable luck and effort. But like many, they are reluctant to pay thousands of dollars for in vitro fertilization, especially if an over-the-counter cough syrup could help them along. As she points out, if a $5 bottle of cough syrup might help, “it’s worth a shot.”
After four months of taking the cough syrup, O’Brien conceived, although she later suffered a miscarriage. But she is convinced that the syrup played a role in helping her get pregnant.
Colette Bouchez, a U.S. medical journalist, included a chapter on cough syrup in the bestselling book Getting Pregnant, she co-authored, and has heard hundreds of anecdotes about its effectiveness.
“It’s not a cure-all for every fertility problem,” she said. “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. But the fact is, for some women, it works.”
Here’s how. Some cough syrups contain guaifenesin, a tree bark extract that works as a natural expectorant, thinning the mucus in the lungs and making it easier to breathe.
In the 1980s, some women began to notice that these expectorant cough syrups also seemed to affect their cervical mucus, leading to speculation that they could thin it out enough to help sperm get through. The idea is not that far-fetched. Progesterone-based birth control pills work, in part, by producing the opposite effect, thickening cervical mucus to prevent sperm from getting through.
In 1982, a Pennsylvania doctor named Jerome Check published an article called “Improvement of cervical factor with guaifenesin” in the Journal of Fertility and Sterility. It documented a study of 40 couples who had been attempting unsuccessfully to conceive for at least 10 months. 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.
And more surprisingly, 15 of those 23 couples 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.”
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. No other studies have tested the impact of guaifenesin on conception.
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 guaifenesin, 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.”