Medical professionals count the weeks of pregnancy from the first day of your last menstrual period. At five weeks pregnant, you're around one week past your missed period -- three weeks past the date of conception -- and might suspect you're pregnant. In addition to missing your period -- a symptom caused by the hormone progesterone preventing the breakdown of the uterine lining -- other pregnancy symptoms often appear during this week.
Around 70 percent of women experience nausea or vomiting -- or both -- in early pregnancy. This symptom often indicates a healthy pregnancy. Increased blood flow through the kidneys can cause frequent urination. Increases in the hormone progesterone, produced first by the corpus luteum and later by the placenta, can cause fatigue. Breasts and nipples in early pregnancy may tingle, itch and swell as the milk ducts and breast tissue expand. The hormones estrogen and progesterone, along with the hormone chorionic sommatomammotropin, can also cause breast growth during this early stage.
Certain symptoms can be warning signs that something is wrong with the pregnancy. Call your doctor promptly if you have heavy bleeding or abdominal pain or cramping. Bleeding and pain can indicate a possible miscarriage or an ectopic pregnancy -- one that starts to grow in the Fallopian tubes or in another location outside the uterus, such as in the cervix. Ectopic pregnancies can cause life-threatening bleeding if they grow big enough to rupture the Fallopian tube. So be sure to check in with your doctor at the first signs of pregnancy.