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What to expect in the first weeks of pregnancy

Your pregnancy test is positive. With that result comes many questions: What early pregnancy symptoms should I expect? When will pregnancy symptoms start? What’s happening inside of me right now? What has happened so far? Is what I’m experiencing normal? 

Whether you’re overjoyed with the knowledge that you’re pregnant or you’re filled with anxiety — or a mix of both — not knowing what is happening or what to expect can feel overwhelming. Here, we share what’s occurred since your last menstrual cycle (spoiler alert: It’s a lot!) and what you can expect through the first few weeks of your pregnancy. 

Pregnancy timeline: Symptoms and what to expect


2-3 weeks since last menstrual period (doctors refer to this as 2-3 weeks pregnant) 

  • Ovulation and conception2,4
  • Single-cell zygote becomes a blastocyst (ball of cells)2,4
  • No pregnancy symptoms2

3-4 weeks since last menstrual period (doctors refer to this as 3-4 weeks pregnant)

  • Blastocyst, now called an embryo, implants in uterus2,4
  • Pregnancy hormone hCG now present in urine after implantation4,7
  • Implantation symptoms: Slight cramping, spotting or nothing at all4,7

5 weeks since last menstrual period (doctors refer to this as 5 weeks pregnant)

  • Embryonic period begins2
  • hCG levels continue to rise7
  • Early pregnancy symptoms remain possible7

The first four weeks of pregnancy

You’ve probably heard that pregnancy lasts about 40 weeks. However, during the first two weeks of how doctors date your pregnancy, you’re actually not pregnant — yet (while this may sound confusing, bear with us). Week one of the pregnancy timeline starts on the first day of your last menstrual period. This means that at two weeks into the timeline, if you haven’t ovulated yet, you’re definitely not pregnant. Rather, your body is preparing for the chance of pregnancy, just as it does during every menstrual cycle.5,6 

Ovulation which is when a mature egg is released from your ovary, typically occurs 12 to 16 days before your next period. Fertilization may occur if the egg meets a sperm in the fallopian tube. The egg and sperm combine to form a single cell called a zygote. The zygote then travels through the fallopian tube, dividing and multiplying, forming a ball of cells called a blastocyst. Around four weeks into pregnancy, the blastocyst implants itself in the lining of the uterus, which is thick with tissue with a good blood supply, just in case implantation occurs. And when implantation does occur, that blood supplies vital nourishment to what is now called the embryo.1,2,3,5 

Early pregnancy symptoms

Slight cramping and spotting can sometimes occur during implantation.4,7 You might confuse this cramping and spotting with the start of your period. But once implantation occurs, the placenta will begin producing the pregnancy hormone hCG.4 This hormone has several important tasks, including producing estrogen and progesterone to maintain your uterine lining. This production of progesterone also prevents menstruation and the start of a new cycle.4 Your missed period is often one of the first signs of pregnancy.6,7

But even before you miss your period, rising levels of hCG can confirm the pregnancy. The Clearblue®  Early Detection Pregnancy Test provides early detection of the pregnancy hormone, so you can test 6 days sooner than your missed period.8 

You can also thank a combination of increasing hormones for early pregnancy symptoms, which may include:6,7

  • Fatigue
  • Tender, more sensitive breasts that may grow larger
  • Nausea and/or vomiting (also called morning sickness, although it can occur at any time)
  • Mood swings
  • Constipation and/or an increased need to urinate
  • Food cravings or aversions
  • A heightened sense of smell
  • Headaches
  • Heartburn
  • Bloating

You may be experiencing some of these early pregnancy symptoms, but don’t worry if you’re not. Some women are overcome with fatigue and/or nausea throughout their first trimester, while others experience few pregnancy symptoms. Both experiences are normal. 

5 weeks pregnant

By now you’ve likely had a positive pregnancy test or you’ve realized you need to take a home pregnancy test due to a missed period and/or early pregnancy symptoms. No one has to know you’re pregnant except you and your healthcare professional; most women don’t start showing until the second trimester, which begins at 12 weeks. Although the embryo is only about the size of a sesame seed, big changes are happening. 

At five weeks pregnant, the embryonic period starts. According to The American College of Obstetricians and Gynecologists, between weeks five and eight of pregnancy, the brain and spine begin to form, cardiac tissue starts to develop, parts of the face begin to take shape, the inner ear develops, and arm and leg buds form, complete with webbed fingers and toes. The digestive tract also appears as a long tube, all in an embryo only about a half-inch long.1, 2, 3, 4

After having a positive pregnancy test, it’s important to make an appointment with your ob-gyn so you can receive proper guidance, instruction and monitoring. Your ob-gyn can also give you additional information on what to expect during the remainder of your pregnancy.

  1. Changes During Pregnancy (n.d.), The American College of Obstetricians and Gynecologists, retrieved April 12, 2021, from https://www.acog.org/womens-health/infographics/changes-during-pregnancy.
  2. Fetal development (n.d.), MedlinePlus, U.S. National Library of Medicine, retrieved April 12, 2021, from https://medlineplus.gov/ency/article/002398.htm.
  3. How Your Fetus Grows During Pregnancy (n.d.), The American College of Obstetricians and Gynecologists, retrieved April 12, 2021, from https://www.acog.org/womens-health/faqs/how-your-fetus-grows-during-pregnancy?utm_source=redirect&utm_medium=web&utm_campaign=int.
  4. Pregnancy Calendar: A week-by-week guide (n.d.), KidsHealth from Nemours, retrieved April 12, 2021, from https://kidshealth.org/en/parents/week1.html.
  5. Pregnancy week-by-week, NHS, retrieved April 12, 2021, from https://www.nhs.uk/pregnancy/week-by-week/.
  6. Stages of pregnancy (n.d.), Office on Women’s Health, U.S. Department of Health & Human Services, retrieved April 12, 2021, from https://www.womenshealth.gov/pregnancy/youre-pregnant-now-what/stages-pregnancy.
  7. Week-by-week guide to pregnancy (n.d.), NHS, retrieved April 12, 2021, from https://www.nhs.uk/start4life/pregnancy/week-by-week/1st-trimester/week-4/.
  8. 71% of pregnancies can be detected 6 days before the missed period (5 days before the expected period).