sex one week before my partner menstrual date

Hi,
Welcome to ehealthforum,
If she was during her fertile days at the time of intercourse (which is likely as per the time you describe), the chances of pregnancy cannot be ruled out. You should have considered using emergency contraception within 48 hours of the intercourse to prevent pregnancy. If she has missed her period (especially if she was having regular periods earlier), then she should consider visiting her doctor/gynecologist for examination (to confirm pregnancy related changes/signs in body) and blood/serum HCG level test (to confirm/rule out pregnancy accurately). If pregnancy gets ruled out, further investigations would be started to look for any other underlying cause for the absent periods. Treatment as appropriate would be started based on examination and investigation results to help her.
Take care.