What Causes Irregular Periods While On Contraceptive Pills?

Hello doctor, I'm susmita 28yrs married for 10yrs ,I havnt planned any kids till now as I was studying ,I was on pills for 6-7yrs ,now about 9months I discontinued it , after that I had irregular periods but this month it was on time ,actually sir I want to know if there will any effect on the child if I get pregnant ?