Re: Period or no period? No straight answers!
The reason why it's not a real period is because it doesn't start for the same reason your period starts when you're not on birth control.
When you're not on birth control, your body naturally starts the cycle process a certain number of days before ovulation begins. The unfertilized egg is washed away with the uterine lining during the period, all of which is regulated by the pituitary gland and most of all your HORMONES. Your hormones regulate all of that stuff from day 1-28 (give or take a few days depending on the cycle). It's all a natural body function which is how it differs from when you are on the pill.
On the pill, you don't start your period because of natural hormonal fluctuations and signals. Instead, when you're on the pill, your body is tricked into thinking it's pregnant because of the hormones in the pill. Your body, thinking it's pregnant, allegedly doesn't ovulate. But then your placebo week comes. The half life of a birth control pill is something like 72 hours or something. So once your level of hormones drop enough, that is what triggers the uterus to shed the lining, thereby you get your period. It's still a period but it's a fake period because it doesn't start due to your body's natural time clock, instead it was brought on by the pill causing a dip in hormone level enough to trigger the bleeding.
That's also the reason why, when women skip pills and take them too far apart or whatever, they start having breakthrough bleeding or spotting. At that point, their hormone levels are all weirded out by the skipping that it triggers the bleeding to start at the wrong time.
It all makes a lot of sense if you think about it.