If you have sex a week before your period is due and your period acutely starts, can you still be pregnant and your period start?

No: If a woman has her normal regular menstrual period, she is presumed not pregnant. If she thinks she is pregnant, then doing a urine pregnancy test the week after missing her "normal" period, the week after getting a "strange or abnormal period," or 3 weeks after having sex, should give an accurate result. The pregnancy test needs to be done correctly and read correctly.

Unlikely: The "timing" makes pregnancy unlikely BUT not impossible. Many women have one, two or more "periods" after implantation. To be sure obtain a pregnancy test in 3 more weeks. Hope this helps Dr Z

Unlikely.: You get pregnant when you ovulate not when you menstruate. Hope this helps. Dr.Y