You might be eager to do a pregnancy test as you enter the fourth week of your cycle. Most women use over-the-counter home pregnancy tests. These are simple to use and work by detecting the levels of hCG in your urine-this is the hormone that is produced as soon as the embryo implants in the lining of the uterus (see You are 3 Weeks Exactly).

There are home pregnancy tests that claim to detect a pregnancy six days before your period is due. But if you use one of these and test this early, your hCG levels may not be high enough to give a positive result, even though you might be pregnant.

Trying to get pregnant is an exciting experience, so why not keep a written record-it's a good way to pass time in this interim period while you're waiting to take a pregnancy test. Rather than just noting down the dates of your period and signs of ovulation, use it to record the highs and lows so far.

Once you're pregnant, you can continue to use the diary to record your feelings: for example, your emotions when you saw the positive symbol on the pregnancy testing kit; how you broke the news to your partner and his response; what your baby's first kick felt like; the best and worst aspects of being pregnant. You may also find that letting off steam about your partner's quirks or your mother-in-law's idiosyncrasies is surprisingly therapeutic!

Besides providing a unique record of your pregnancy, keeping a journal can also help you in subsequent pregnancies: for example, you may find it reassuring to look back and find that morning sickness was just a phase.