I want to know that when should we do sex with our partner for making her pregnent.

Varies: If a woman is having regular monthly cycles, she is likely to be most fertile about 2 weeks after the last period started. To improve chances for conception, start having sex 8 or 10 days after the last period started and continue until at least 16 or 18 days after the last period started. She should be taking vitamins (with folic acid) while trying to conceive. Good luck.

14 days before: Ovulation occurs 14 days before the next menstrual cycle. This is the best time to have intercourse.

Days 10-20: If day 1 is the first day of your cycle and your cycles are 28 days, then ovulation is truly on day 14. However, if your cycle is more like 30 days, then is is 14 days prior to when you start the next cycle. So, a 30 day cycle ovulated on day 16. Cover your bases by being sexually active between days 10-20 every other day. Most couples take 4-6 months to conceive when actively trying.