Welcome to HCM,
In a regular menstrual cycle of 28 days ovulation generally occurs on the 14th day of menstrual period.
One can become pregnant due to intercourse done on or around the day of ovulation.
The 5th day of menstrual cycle (counted from 1st day of period) is generally safe regarding pregnancy
As you have started contraceptive
pill from the first day of period and day of sex comes in safe zone, chances of pregnancy are almost nil. Therefore you need not to worry.
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