I would say that anytime any of the pills (except the inactive ones) is missed the % of risk increases.
Keep us posted ..
C~
Whenever missing a birth control pill there is a slight possibility of pregnancy, which is why you are supposed to take the pill as soon as you remember or double up on your next pill.
Best wishes!
Just an echo- if the pills aren't taken as they are meant to be it is possible to get pregnant. I have a nephew because my sister missed the first active pill after her period and an adoptive nephew because my cousin took a 3 day course of antibiotics while on the pill. Another one of my friends gave birth to twins because she would miss a couple days then take several at once and did it so often it messed up her body into dropping multiple eggs.
Anytime you miss a pill, use back up just in case. And only ever use a pill as they're intended.