Well, I heard an interesting one tonight. My wife passed on that on a blog discussing contraceptive use, someone posted a link to a site stating that taking Ortho Tri Cyclen, an oral contraceptive, "ages" the cervix prematurely.
The implication was that if a younger woman takes the pill, her cervix could end up being of an "age" of an older woman, thus preventing pregnancy when desired (and when taking oral contraceptives is stopped).
I had a heck of a time trying to research this on my own.
- I started with googling "ortho tri cyclen" to find out more and examine side effects. I could only find it mentioned on the Wikipedia page for oral contraceptive formulations but no main site with side effects.
- I looked at the pages for the two types of birth control pill (progestogen-only and combined) and didn't see anything like this listed in the side effects.
The cervix undergoes a natural process of development and ageing. The area of the cervix given over to the mucus secreting crypts gradually diminishes from maturity. The number of S crypts decreases from teenage. They are first replaced by L crypts starting at the base of the cervix. Later G crypts replace the L crypts...
"The L replaces S and G replaces L transformations are partially reversed by changes during pregnancy, but they are partially accelerated by the Pill. These circumstances may be simply stated by the expression: a pregancy rejuvenates the cervix by 2-3 years, but for each year the Pill is taken, the cervix ages by an extra year." ("The Discovery of Different Types of Cervical Mucus and the Billings Ovulation Method", Professor Erik Odeblad, Bulletin of the Natural Family Council of Victoria, ISSN 0321-7567, Vol 21 No 3 September 1994, pp3-35).
Following the link to Professor Erik Odeblad's work, I was surprised to find what I considered a much more modest statement (emphasis mine):
The study of the effects of contraceptive pills on the cervix is a difficult task. A considerable amount of work is required for each patient and the time required spans many years, up to 10 years or more. Many women also want to change to other pills or to other methods of contraception, or perhaps now want to become pregnant. It also happens that some pills are withdrawn from the market. To these difficulties are added the normal age changes in the cervix and the dynamic processes which are of constant occurrence. After 3 and up to 15 months of contraceptive pill use, there is a greater loss of the S crypt cells than can be replaced.
Read the quote yourself, but there seems to be no obvious connection (at least in that quote, which is what Woomb itself chose to reproduce) made between S crypt cells, the "age" of the cervix, or the ability to become/stay pregnant.
Lastly, here's a blog post that reiterates the above and might be something similar to what caused my wife to bring this up.
Is there evidence supporting the claim that the oral contraceptive pill (or some specific formulation) "age" the cervix prematurely such that the chances for pregnancy are reduced or eliminated even when no longer taking contraceptives?
As an aside, I'm a former Catholic and very familiar with natural family planning (NFP), of which the Billings method is a type. I find it intriguing that this claim would originate with a natural family planning researcher, as these methods tend to be associated with Catholics/Christians who want to avoid pregnancy while not disobeying the doctrine to which they subscribe.
In Catholic culture, natural family planning is not often pitched as simply that -- avoid pregnancy while not sinning; there tends to be a lot of preaching against other forms of contraception to make them less appealing, probably because NFP involves long(er) periods of abstinence.
I simply add this to shed light on what I think might be a side agenda of various natural family planning groups: to downplay alternative methods (condoms reduce sensation, the pill ages the cervix, etc.) to keep enticement down as much as possible for religious populations.