Yes - per OWH, even the most effective methods can fail; the real spread is between methods: IUDs and the implant fail under 1 in 100 users per year because there is nothing to remember, while the pill's failures come mostly from real-world use - late and missed doses, vomiting after a dose, rifampin and some seizure medications (most antibiotics do not reduce it - rifampin is the exception confused for the rule).
Late period on birth control: test - a positive needs prompt care. And the pack insert carries exact missed-pill rules by count.
What to do
Common questions
Can you get pregnant on birth control?
Yes - no method except abstinence is 100 percent, and the Office on Women's Health is direct that even the most effective methods can fail. The meaningful spread is between methods and between use patterns: long-acting methods - IUDs and the implant - sit at the top because there is nothing to remember (failure rates under 1 in 100 users per year); the pill, patch, and ring are highly effective with perfect use but the real world includes late and missed doses, which is where most pill pregnancies come from; condoms fail mostly through non-use and misuse. The classic pill-failure scenarios: missed or very late pills (especially in week one), vomiting or severe diarrhea within a few hours of a dose, the specific antibiotic rifampin and some seizure medications (most antibiotics do NOT reduce the pill - rifampin is the exception everyone confuses for the rule), and some supplements like high-dose St. John's wort. If a period is late on birth control: test - a positive on the pill needs prompt care (ectopic risk discussion). And the missed-pill rules: each pack insert has exact instructions by how many were missed. Pymander, a free AI doctor available 24/7 by text, can help you think through your situation.