By the time you’re four weeks pregnant, you can usually get a clear positive on a urine pregnancy test.

It’s a funny thing, but your egg may have only been fertilized in the last two weeks. Still, the dating for pregnancy begins with the start of your last menstrual period.

By entering this date into a due date calculator, you can estimate the day your little one might enter the world.

The Pregnancy Quiz: Am I Pregnant?

Changes in your body

changes in your body

Your baby has just implanted into your uterine lining. Your body is now beginning the incredible series of changes that will take place over the next 36 weeks, give or take a few.

Weight Gain During Pregnancy
If you’re starting pregnancy at a healthy weight, or a body mass index (BMI) between 18.5 and 24.9, you should plan to gain between 25 and 35 pounds over the course of your pregnancy. If you’re starting pregnancy with a BMI below 18.5, your doctor may recommend gaining 28 to 40 pounds during your pregnancy. If you’re starting pregnancy with a BMI above 30, your doctor may recommend that you gain 11 to 20 pounds over the course of your pregnancy.

One of the earliest physical signs you’ll experience is a missed period, which indicates that your progesterone levels are taking over your hormonal balance to sustain your pregnancy.

As your baby develops, your body will produce more and more human chorionic gonadotropin (hCG) as well. This hormone is present in your blood as soon as seven to 11 days after conception. It comes from the cells that eventually turn into the placenta.

At four weeks, normal levels should range between five and 426 mIU /ml.

Your baby

week 4 baby

Your baby is currently a collection of cells called a blastocyst. Development this week is rapid. Around half of these cells will become an embryo the size of a poppy seed by the week’s end. The other half of the cells work to keep your baby safe and nourish its growth.

The size may sound impossibly small, but what’s even wilder is that many of your child’s characteristics, such as eye color, hair color, sex, and more, have already been determined through its chromosomes.

Twin development at week 4

Your first trimester symptoms may be amplified if you’re carrying twins. After all, you have two bundles of joy, so you’re more likely to have higher hormone levels. You may even suspect you’re pregnant sooner than if you were carrying one baby. You can take a pregnancy test this week to find out, but you won’t know the number of babies until your first doctor’s appointment, which is usually around week 8. Your first appointment might happen sooner if you had fertility treatment.

If you’ve had fertility treatments for pregnancy, you may also have your human chorionic gonadotropin (hCG) and progesterone levels confirmed with a blood test. There's nothing to see on an ultrasound yet, but high hCG and progesterone levels may give you a clue that you’re carrying multiples.

4 weeks pregnant symptoms


At this early stage, you might not notice much going on with your body. In fact, some women don’t know that they’re pregnant for weeks if they aren’t keeping close track of their menstrual cycles or if their cycles tend to be irregular.

On the other hand, by week 4 of your pregnancy you may experience the following:

  • breast tenderness
  • exhaustion
  • frequent urination
  • nausea
  • heightened sense of taste or smell
  • food cravings or aversions

Overall, the symptoms in week four often mimic your normal premenstrual symptoms. So much so that many women swear their periods will start at any moment.

Here are some home remedies for common early pregnancy symptoms:

  • To relieve sore breasts, wear a supportive bra during the day and to bed if it helps.
  • Tiredness can be quelled by taking a catnap in the afternoon. Exercise can also give you a much-needed boost of energy when you’re feeling sluggish.
  • You may want to moderate your liquid consumption if you’re finding yourself in the bathroom too often. Don’t cut back too much, though, because you need the hydration now more than ever.
  • Nausea is uncommon this early, but if you do experience it, try eating small, frequent meals and avoiding foods that trigger sickness. Many women find relief while snacking on carbohydrates and tart foods.

The Best Nausea Remedies for Morning Sickness

Things to do this week for a healthy pregnancy


Once your pregnancy test turns positive, you’ll want to call your doctor or midwife to set up your first prenatal appointment. Don’t worry if the due date is far in the future. Most women are seen for the first time around week eight.

Depending on your care provider’s protocol, you may also need to head into the office to have some preliminary blood work that will confirm pregnancy and check your hormone levels. One test will check your hCG. This number should double about every 48 to 72 hours. The other will check your progesterone levels.

Both tests are repeated at least once to assess the increase in numbers.

Even at week four, it’s never too early to start healthy habits. Try eating whole foods, avoiding smoking and alcohol, and, if you aren’t already, start taking a prenatal vitamin.

Exercise is also a great way to ease pregnancy symptoms and keep your body and baby healthy. Typically any activity you were doing before pregnancy is safe to continue in the first trimester. For vigorous exercise, you may want to consult with your doctor about certain modifications that might be necessary.

When to call the doctor


While you shouldn’t worry, it’s important to know that miscarriage rates are high in early pregnancy. Researchers estimate that up to 20 percent of known pregnancies end in miscarriage, many of which happen around the time a woman expects her period to start.

At week four, miscarriage is called a chemical pregnancy since the embryo cannot be detected on ultrasound, only through blood and urine testing.

Signs of miscarriage include cramping, spotting, and heavy bleeding. If you experience these symptoms, don’t necessarily fear the worst. As the blastocyst buries deeper into your lining, you may have spotting and discomfort. In other words, not all blood means miscarriage is imminent.

The best way to gauge what’s going on is to keep an eye on yourself and speak with your doctor about the symptoms you are encountering.

The waiting game

The first weeks can seem difficult and like a major waiting game. It’s easy to compare notes with friends and family. Keep in mind that each pregnancy and each woman is unique. What may have worked or been an issue for someone else might not apply in your situation.

If you ever have questions or concerns during pregnancy, your first resource should be your care provider. They’re used to frequent calls and even “silly” questions, so ask away!