Thursday, January 15, 2004

Ovulation mystery resolved: the data never existed

Two days ago I discussed an article showing that women have multiple waves of follicular development during the ovarian cycle. Yesterday I posted the observation that multiple news sources had cited the same study as showing that multiple ovulations occurred during a single cycle, even though the paper didn't seem to include any multiple ovulation data.

I e-mailed one of the co-authors of the study (Angela Baerwald) to inquire about the discrepancy, and she kindly (and promptly!) replied that there are no multiple ovulation data; all of the earlier waves of follicle development observed were anovulatory. Here's a portion of her response:
The primary finding of our study was that women exhibit waves of follicular development during the menstrual cycle. Only the final wave of the cycle was ovulatory. All preceding waves were anovulatory. Unfortunately, there were a few reporters that could not differentiate between follicular development and ovulation. They took it upon themselves to state that women ovulated more than once a month which was not what we found. As one reporter often feeds off of another, there were a significant number of media reports that focused on multiple ovulations. We sincerely apologize for the confusion.
She also included another paper that provides more details about the multiple follicular waves – it's a great read if you're interested in this phenomenon (see the abstract or a PDF of the manuscript if you want to find out more). Here's a little teaser: it looks like the waves of follicular development occur throughout the entire ovarian cycle and do not just take place during the follicular phase.

So this now looks to be a great example of the media misinterpreting, and misreporting, research results. I'll probably use this in my classes as an example of why reading the primary literature is a very good thing, and just how professional misreporting such as this can sound (all the misreported articles I've found include quantitative descriptions of the non-existent data). Here's an annotated list of the most relevant web sources I've found so far:
Official sources on the paper:
  • Journal's abstract: Very concise and well written; clearly shows the lack of multiple ovulations.
  • Journal's summary of the research: Scroll down to find this paper; this is a good summary that lacks any mention of multiple ovulations.
  • Press release: This is by the Canadian Institute of Health Research, and it's relatively clear that there were not multiple ovulations. However, it does say that for many women there may be an egg ready to ovulate at multiple times during the cycle.
  • Good articles (no mention of multiple ovulations):
  • WebMD: An excellent article that clearly differentiates between ovulation and follicle development, and also extrapolates about why this study shows the rhythm method might not work well.
  • Women's Health Matters: Their article is (entirely?) based on the press release, and as such includes no mention of multiple ovulations.
  • Articles including multiple ovulations:
  • The New Scientist: First line of the article is "Women may ovulate more than once a month ..." and it goes on to say that "ten per cent of the women studied released two eggs in the same month."
  • AZCentral (from the LA Times): Article starts by discussing the belief that women ovulate once a month, and then says that this new study counters that belief, including the statement that "Most of the 63 women studied released an egg just once a month but, in six cases, eggs were released twice." The same article is found at the Sydney Morning Herald.
  • MSNBC: Article starts with "No wonder the rhythm method does not work so well for birth control — scientists in Canada said Tuesday they had found women sometimes ovulate several times a single month." Further along it says, "Thirteen of the women ovulated multiple times, in various different ways."
  • Health24: An article that tries to delve a bit more into the implications of multiple ovulations. It starts off with the first sentence, "...women sometimes ovulate more than once a month" and then later includes that "... only 50 of the 63 women really had normal ovarian cycles. The other thirteen ovulated many times in one month and in different ways." [note: I'm now getting an error that this site may be unavailable for international (non-African) users]
  • The paper referenced above is: Baerwald, A. R., G. P. Adams, and R. A. Pierson. 2003. A new model for ovarian follicular development during the human menstrual cycle. Fertility and Sterility 80:1, pp. 116-122.

    The paper detailing the waves of follicular development is: Baerwald, A. R., G. P. Adams, and R. A. Pierson. 2003. Characterization of Ovarian Follicular Wave Dynamics in Women. Biology of Reproduction 69:3, pp. 1023–1031.

    1 comment:

    Radagast said...

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    Wow! This is a beautiful and thorough piece of detective work. Thanks for this.
    January 16, 2004, 3:23:24 PM PST – Like – Reply