Persona vs. Clearblue

Santa knows if you've been naughty or nice, and so, apparently, do a few other people:

Sales of pregnancy tests typically soar in the first months of the year, as more women than usual tend to become pregnant -- or just think they are, according to Inverness Medical, the makers of the Clearblue Easy pregnancy tests.

Dr. Brad Imler, president of the American Pregnancy Association, told Reuters Health that most births occur in August and September -- nine months after December and January. Furthermore, winter holiday months tend to be very stressful for women, and stress can cause women to miss their period -- often the first sign of pregnancy, Imler said.

He explained that the best way to distinguish a true pregnancy from a false alarm is to focus on additional symptoms of pregnancy. These include tender or swollen breasts, fatigue, nausea, headaches, backaches and a change in appetite.

One more symptom I'd add is urinary frequency. Of note, all these additional symptoms are also useful if you're on an extended/continuous period control regimen. But I digress.

Inverness Medical is an American company who owns Unipath Ltd. Unipath is the maker of Persona, an OTC birth control method, not available in the U.S. What is available here from Inverness is the Clearblue fertility monitor.

Persona consists of a small monitor with a microcomputer, and urine test sticks. And so does Clearblue.

Clearblue

Persona

Although Persona and Clearblue look similar, and work on the same principle, they are not one and the same.

With Persona, you pipi on a test stick, place the stick in a monitor slot, and the monitor indicates (via lights) when you may, or may not have intercourse. Same with Clearblue, except its monitor indicates when you're most likely to conceive (most fertile). [This is how this happens: the test stick converts urinary sex hormones to something readable by the monitor. The monitor reads the hormone levels, and uses a pre-programmed algorithm to interpret the levels.]

Aha, you say, then why don't I just go ahead and use Clearblue, avoid intercourse when the monitor indicates I'm fertile, and voila!, my own little OTC birth control method. You shouldn't do that, and here's why.

Persona uses a different algorithm than Clearblue. Persona tells you when it's likely you'll become pregnant; Clearblue tells you when it's most likely you'll become pregnant. What's the difference?

Persona indicates the widest interval during which it's likely you'll become pregnant. It asks you to abstain during that entire interval, and thus offers you good protection against a pregnancy. In contrast, Clearblue indicates the narrowest interval during which you are most likely to become pregnant. If you're interested in conception, this is exactly what you want; to maximize your chances by minimizing the interval--having intercourse on the [almost] exact day when you ovulate. However, if you're interested in pregnancy protection, the narrow interval leaves you vulnerable. You want a reasonable time interval buffer on either side of ovulation.

Remember: after ovulation, an egg lives for ~12 to 24 hours; after ejaculation/penetration sperm live from 3 to 7 days.

An aside: Cervical mucus can act as a sperm reservoir, so fertilization (egg + sperm) can be removed from intercourse. This is why you can have a romantic night on Saturday, and on Wednesday, while waiting on line at the DMV to renew your license, sperm could be on its way to meet and fertilize the egg. [Something to ponder next time you're at the DMV.]

Bottom line: Persona is a birth control method. Clearblue is a fertility monitor. They should not be used interchangeably.