Does anyone know if it is possible to conceive on the day your period is due and have a positive test 4 days later. My friend reckons it is but I think that as the egg takes time to travel and implant and then give out the pregnancy hormone it would be impossible to have a positive result 4 days later even if you ovulated on the day your period was due? My friend had been trying to get pregnant with a long term partner and had her LMP on 10th October. She was due her period on 6th Nov (her cycle is usually 28-30 days long) she had a falling out with her partner and had a one night stand on 6th Nov when her period was due using protection. However the condom split but he had not ejaculated. She did a test 4 days later and found it positive. I think that the baby is her partners and not the one night stand. She is worried about it though.:( . What do you think ?

It sounds as though the baby is her partner's. Usually it takes 11 - 13 days after you have the first day of your period to be fertile (ovulate). That would account for the positive test in that she was already pregnant when she had the one night stand.