Hello and welcome to HCM
Conception and hence pregnancy
takes place only when a sperm meets the released ovum.
Ovum is released during ovulation which occurs 14 days before menstruation
The released ovum is viable for two days.
If intercourse takes place within these two days then only the conception takes place.
You have mentioned that the periods followed the time of intercourse so the chances of pregnancy are negligible at this period of time.
Thanks and take care
Dr Shailja P Wahal