Hello,
Your partner is 20 days due to her periods. She had 3 card tests that showed negative report for HPT. You had protected sex with her. You have not mentioned if she had been taking regular CP or had taken emergency CP or had been using condoms. Ideally if you had protected sex she shouldn't be pregnant but in case of carelessness like condom breaking, forgetting to take pills in time, etc. may increase the chances of her getting pregnant.
You are suggested to get her clinically examined by an
OBGYN, get her per vaginal check up done to detect bulky uterus. Get USG (Uterus with fallopian) tubes done to confirm
pregnancy or detect ectopic pregnancy. Delay in periods may also be due to other factors like stress (emotional and physical),
anemia, poor general health condition, low weight or being too obese,
hormonal problem,
thyroid problems, etc. She will be accordingly treated. She should stay away from addictions if any.
Take care. Hope I have answered your question. Let me know if I can assist you further.
Regards,
Dr. Nupur K., General & Family Physician