hello sir, thnx fr trusting HCM doctors fr ur health related queries.. i guess ur concern is to know the reazn fr delayed periods w.r.t intercourse...n tests to confirm pregnancy i would like to give anzrs with a small discussion like below... in universe women is known to give birth fr a new life...her body is being designed lik tat by god,,, the part where baby is grown inside women is called womb(medically as uterus) every month on the inner surface of womb there occurs coating of small small blood vessels ...tis coating serves as bed for baby to get attached or serves as nursing environment...wen women doesn t have intercourse n no sperm is there to meet ovum,,,there is no baby formed..so womb decides tis coating bed like thing is of no use, as no baby is formed,,,so it sheds it off,,n women get bleeding or popularly called as menses...tis is normal natures rule of menstruation.... wen men n women have intercourse,sperm meets ovum,,,and baby is formed(medically called as embryo).tis baby gets attached to inner surface of womb(medically called as uterus)...tis attachment is by means of small small blood vessels present or coated like on the inner surface of womb...wen attachment is confirmed then body decides tat inner surface of womb is used by baby, so i cant shed it off...so no bleeding occurs/menses occur...or the expected menses is missed....popularly told by women i missed my periods...tis is the normal reason or mechanism of not getting the periods or delay in the expected date of periods after intercourse.... sometimes there may be some abnormality in ovaries or uterus,,so women would be getting delayed menses.,,,tis is pathological ,,means to say abnormal .... so wen couple s hav unprotected intercourse,,women gets pregnant she misses her periods as per normal natures rule....so ppl assume she is pregnant....but if she is having abnormality as told abv tis will also cause delay in menses...tat causes double confusion....... well with tis discussion u can try out my suggestions:- 1.after 4-5 days of missed periods u can go fr urinary pregnancy test .. (sir for ur kind information no test in medical field gives 100% assurance of correctness...its the cumulative reports of each test that gives assurance) 2.well still u wanna a higher level of test to confirm it..u can go fr blood test of beta hcg assay... 3.if still in need of higher version,,u can go fr scan(usg scan of abdomen n pelvis)as it gives image of growing baby(embryo)inside womb...!!!!!! i hope tis was informative enough ,helpful n useful fr ur query.. regards:dr.sudha rani panagar...