In the average menstrual cycle, ovulation happens at the end of week 2 after your last period started. Ovulation is when an egg is released from the woman's ovaries. Conception usually happens when a couple have had sex, unless you're having assistance such as IVF (in vitro fertilisation) treatment. Sperm from the man travels through the woman's womb and up into the fallopian tubes, which connect the ovaries to the womb. Here it meets a mature egg. When the sperm penetrates the egg it is called fertilisation.
If you've been trying for a baby, you'll probably know that the end of this week (officially pregnancy week 2) is the most fertile stage of your menstrual cycle, and may have been making a special effort to conceive. Some women know exactly when they are ovulating and notice signs such as breast tenderness, a slight temperature increase, and changes in vaginal discharge. You can also buy special ovulation prediction kits, which test your hormone levels to find out when you're at your most fertile. Try not to get stressed about conceiving - sex should be fun and relaxing. Take your time and try different positions, aiming for deep penetration.
It's very important not to worry or get stressed if you don't get pregnant straight away. Having sex two or three times a week is usually enough, and six out of ten couples conceive within 6 months of starting to try for a baby. Many couples take up to 2 years, so if you don't get pregnant in 6 months then it doesn't mean you're not able to have a baby. Don't feel under pressure to have more sex or to have sex on particular days - there's still an element of chance involved even if sperm is released at exactly the right time. Reducing stress and being relaxed is also thought to improve your chances of conception. This includes Dads!