Coasting
When on 'The Pill' a girl gets a pill sheet marked with days of the month. For most of the month the pills they take have an effect, but for a few days every month there's apparently no need for them to take any additional pills. To keep it simple however the pill sheets contain pregancy-friendly sugar pills to keep the girls in the habit of taking a pill every morning. When a girl is taking these sugar pills, she is coasting on the previous weeks dosage.