Epidemiology: Case Control selection criteria

[bwbddb]

For you epidemiology buffs:
A recent practice question puzzled me:

If a physician were to design a study to determine if accupuncture can be used to induce labor, would he choose a case control or cohort study design (assuming only those options)?

The 'correct' answer to the practice question was case control. However, my understanding of case control is that you always choose cases based on disease/condition (in this case, labor) and look back to examine exposure (accupuncture). With a rare exposure, this isn't effective. Wouldn't a cohort study be a better design, or can you choose cases based on exposure? The complete question can be found in 'Blueprints Clinical Cases: Obstetrics and Gynecology' 2006 pg 132 which is available on Google Books.

[padanarm]

I'm not a medical expert, but case control does make more sense than a cohort study. With respect, perhaps you don't fully understand the difference between the two.

Perhaps there's a course book or teo you could read, or you may have access to the internet?.

[bwbddb]

Response to Padanarm:
I'm a third year medical student and have done quite well in my education in epidemiology. If one were to set up a case/control study for this, you would have to choose women with the disease/condition (labor) and then match them to controls without the disease/condition (women not in labor). That would not supply you the necessary information. Alternatively, you could suggest choosing "cases" based on their use of acupuncture, but that would not be a case/control study, as you are choosing cases based on exposure, not outcome.
So, please let me know how you would design a case/control study for this and how that would be superior to a cohort study. Thanks!