You are not "officially" pregnant yet, but the first week of development starts on the first day of your last menstrual period. It may sound a little confusing, but your body starts counting the weeks of pregnancy moving forward. If you are actively trying to conceive, now is likely when you are tracking ovulation and waiting for your fertile days to TTC.
Tips for this week
It's a perfect time to learn the signs of ovulation so you can increase your chances of conception. Vaginal mucus can be checked for fertility by observing the color and texture: fertile mucus is white or yellow and stretches easily between the fingers. It is known as egg-white cervical mucus (EWCM).
Starting a pregnancy diet is also a great idea at this point. Stopping smoking and drinking and increasing your folic acid intake are important ways to help ensure a healthy baby. Folic acid helps prevent neural tube defects in the first weeks after conception.
Learn More:
Pregnancy: Week 1
All 42 Weeks: Week by Week