My menstrual cycle is 40 days. its regular, my period comes monthly. does it affect pregnancy especially in early ultrasound to determine age, conception date and due date? how many days after sex to get positive urine test result? thanks.

3 weeks: Conception occurs within day or so of the sex. It takes about 3 weeks for the embryo to make enough HCG for a positive pregnancy test. Blood test may be done a day after a missed period. Home pregnancy tests should be done 4-5 days after the missed period. If the result is negative repeat the test in 4-5 days. Use first morning urine and follow instructions for the test carefully