Can poppyseed oil help infertile couples conceive?

Here’s something you don’t see in the New England Journal of Medicine every day: Flushing fallopian tubes with a poppyseed oil-based solution may help a woman to conceive — and one of the key researchers of the paper thinks he’s likely living proof of the technique’s efficacy.

For decades, doctors have noticed that some couples who had previously been struggling to conceive became pregnant shortly after an imaging study of the woman’s uterus and fallopian tubes.

Now, a randomized study strongly suggests a particular chemical used in that procedure may be to thank.

During a hysterosalpingogram, a standard part of infertility evaluations done in many countries including the United States, a doctor takes an X-ray of a woman’s uterus and fallopian tubes that can be seen because of an injected contrast fluid.

In its early days of use in the 1920s, the contrast medium was an oil-based one, according to Dr. Catherine Spong, deputy director of the National Institutes of Health’s Eunice Shriver Kennedy National Institute of Child Health and Human Development. But “over time, there was a switch to a water-based media,” she said, in part because doctors thought it might not be a great idea to put a foreign substance into the reproductive tract.

In the current study, researchers randomized more than 1,000 women across 27 hospitals in the Netherlands who were having this exam done to either receive a poppyseed oil-based contrast or a water-based contrast.

Within six months after the procedure, about 40 percent of the women whose test used a poppyseed oil-based contrast became pregnant and had children — 10 percentage points more than the women whose test used a water-based contrast.

The difference was remarkable, said Dr. Ben Mol, a professor of the University of Adelaide and one of the lead authors of the study, published Wednesday. “I was surprised by the magnitude of the effect. It’s so clear,” he said. Pregnancy rates immediately jumped in the group that had oil-based contrast used in their test — some were pregnant within a month.

This study does not concretely establish how the contrast makes this happen. There are a few theories about how it might work, though: The contrast could be flushing mucus out of the fallopian tubes or it could making endometrial tissue more receptive to a pregnancy.

And the study does have a few limitations. The trial couldn’t be blinded because the imaging protocols differed slightly between the groups. Researchers also only included women under 40 years old and women who were all otherwise healthy — that is, they didn’t have endocrine disorders or any other condition that might affect fertility.

Nevertheless, “this is a very well-done study,” said Spong, who was not involved in the research. Other studies on the subject “were much smaller than this, and were not as rigorous as this.”

Still, more large-scale studies would be helpful to see if there are any very rare issues associated with the oil-based contrast, she added.

In his opinion, Mol believes doctors should tell couples about these findings, especially if they are considering in vitro fertilization. “Not informing women about this study and then starting [in vitro fertilization] … I think it’s not the best practice,” he said — especially since a hysterosalpingography costs much less than IVF protocols. An oft-cited American Society of Reproductive Medicine estimate from 2006 for one round of IVF is $12,400; a hysterosalpingography can cost around $1,000 in the US.

Mol and his colleagues are planning to follow up with their study volunteers again in five years to see if there is a noticeable long-term effect on fertility. (Guerbet, the company that manufactures the oil-based contrast, will be funding the follow-up studies; the company gave no financial support and had no influence on the original work, Mol said.)

Based on his own family’s experience, Mol suspects the team will see a long-term impact.

“My parents were trying to conceive for eight years,” he said. His mother had the test done in 1964, and then became pregnant with him a month later. And a few years later, Mol’s younger brother was born. “If she lived nowadays, then I probably would not have existed,” he said, “because, very likely, my mother would have had IVF instead of waiting for eight years.”

“I’m glad that I exist.”