4 Weeks Pregnant

You’re in the very early stages of your pregnancy, but your body is already kicking into gear, working around the clock to support and nurture the growing baby-to-be that’s beginning to make itself at home in your uterus.

Your little one is still tiny—almost microscopic—but she’s very busy. Read on to learn about your baby’s early developments, the changes you may start noticing in your own body, and everything you can expect at the 4-week mark.

At 4 weeks pregnant, your baby is starting her transformation from a tiny cluster of cells into an embryo. Here’s a rundown of what’s happening to your (very) little one.

From blastocyst to embryo

However, a lot is happening right now on the cellular level. Your fertilized egg has completed its journey to your uterus and implanted itself in your uterine lining. That’s where it is right now. 1 This process establishes the connection between you and the baby, which will provide the nutrients she needs to grow.

Following implantation, the fertilized egg—now called a blastocyst—divides itself into two layers:

• Epiblast: This layer will eventually form the embryo and ultimately become all the organs, tissues, and systems in your baby’s body. Key among these is the neural tube, the foundation of your baby’s brain and spinal cord.
• Hypoblast: This layer will develop into supportive structures, such as the yolk sac, which will provide nutrients until your placenta is functional. Once it’s fully formed, your baby will share your own blood supply, and the placenta will manage nutrient delivery and waste removal.

Alongside these layers, the blastocyst will also form something called the amniotic sac, which will protect your baby-to-be as she grows.

At this early stage, your baby is just about the size of a poppy seed, measuring approximately 1 mm (0.04 in) in length. However, she’ll grow much bigger very soon.

What does a 4-week ultrasound look like?

You probably won’t have an ultrasound this week. Four weeks is just about the earliest it’s possible to confirm your pregnancy, so your first prenatal visit is a couple weeks in the future.

That said, if you did have an ultrasound, you might see a small, fluid-filled sac called the gestational sac. 2 Your baby herself would be too small to be detected at this stage.

You won’t be able to see your developing embryo or detect the fetal heartbeat until you’re at least 6 weeks pregnant. 3

Your body is changing rapidly to support your pregnancy, even if you’re not feeling many pregnancy symptoms yet. Let’s take a look at some of the early signs of pregnancy you might start noticing in the coming days:

Nausea

Nausea, known as morning sickness, is arguably the most infamous early pregnancy symptom. It probably won’t hit you just yet, although that isn’t guaranteed—it hits some women earlier than others.

If it does, hang in there. Morning sickness typically doesn’t last long past the first trimester. 4

Breast tenderness

Your hormones will surge in your early pregnancy, which may lead to breast tenderness, soreness, or a sense of “fullness.” This symptom can feel similar to premenstrual tenderness, though it may be more intense and longer-lasting.

Fatigue

Your body will release progesterone, a pregnancy hormone, which may leave you feeling unusually tired, even with a regular sleep routine. This symptom can be annoying, but it isn’t anything to worry about, and it doesn’t mean you’re getting sick. 5

Mild cramping or spotting

You may experience mild cramping or light spotting due to the egg embedding itself in your uterine lining. This is called implantation bleeding. It can either be light pink or brown, and is usually less intense than a normal period.

Bloating and digestive changes

Hormonal shifts, especially that surge in progesterone, can slow your digestion and make you retain more water than usual. This, in turn, can lead to feelings of discomfort in your abdomen, such as bloating, gas, and fullness.

Don’t confuse this with the development of your “baby bump,” which is still a ways away and will be caused by your uterus shifting and growing to accommodate your baby. You’ll probably need to wait sometime between weeks 12 and 16, which is when you’ll start to show in your pregnancy.

Mood swings and emotional sensitivity

This is another symptom you can blame on your hormones. Your spiking levels of estrogen and progesterone may impact your body’s ability to regulate your mood, leading to mood swings or heightened emotional sensitivity.

At this point, your hormonal balance has changed enough that a home pregnancy test will return accurate results (before week 4, there’s a good chance that taking one will result in a false negative).

This means you can finally confirm what you may already suspect. Here’s when you should test and how to interpret what you see:

When to test for accurate results

The earliest you can take a pregnancy test is usually on the first day of your missed period. By this time, your levels of human chorionic gonadotropin (hCG), the hormone that pregnancy tests look for, will typically be high enough to return clear results.

Testing earlier than this can lead to faint or unclear results, as your hCG levels may still be low.

On that note, it’s best to test first thing in the morning. This is generally when your urine will be most concentrated (because you haven’t had anything to drink all night). Avoid testing later in the day, especially if you’ve had a lot of water recently, since the better-hydrated you are and the more diluted your urine is, the fainter the result will be.

What does it mean if you see a faint line on your test?

If you see a faint line on your pregnancy test, it usually indicates a positive result, as the test has detected at least some hCG in your urine. The result is probably faint because you tested a little early and your hormones haven’t had as much time to rise yet.

Repeat the test in a few days just to be sure. If you are, in fact, pregnant, your hCG levels will continue to steadily increase, leading to a clearer positive line the next time around.

False negatives and retesting

False negatives can occur if you test too early, such as a few days before your missed period or immediately after implantation.

The good news is that hCG levels double approximately every 48 hours in early pregnancy. If you get a negative result but are still pretty sure you’re pregnant, you can find out whether it was a false negative by waiting 2–3 days and trying again. 6

Even though it’s still early days, you can start preparing for your pregnancy. Here are a few steps you can take right now:

Scheduling your first prenatal appointment

Once you have a positive pregnancy test in hand, it’s time to schedule your first prenatal appointment.

Most doctors recommend booking this for around week 8, although if you have any abnormal symptoms or health concerns, there’s no harm in getting seen sooner (e.g., if your family history contains a lot of pregnancy complications, etc.).

When you get seen, your provider will run through what you can expect from your pregnancy, answer any questions you have, and conduct a few tests, including a blood pressure check. They may also take a blood sample and perform an ultrasound, too, although that depends on how they feel your pregnancy is progressing so far.

How to choose a healthcare provider

Before you can actually make your booking, you need to pick a healthcare provider. It might surprise you to learn that you don’t actually have to get seen by a doctor, although many women do.

You have two options:

• OB-GYN: An OB-GYN is a physician (a doctor) who specializes in pregnancy and childbirth. You should get seen by a specialized physician if your pregnancy is considered “high-risk,” e.g., if you’re over 35 or have a chronic condition like diabetes.
• Certified Nurse-Midwife (CNM): Midwives provide prenatal care and deliver babies in low-risk pregnancies. If you want less “medical”-feeling care, you can opt for a midwife instead of a doctor, although midwives collaborate with OB-GYNs if and when they encounter complications.

If your pregnancy isn’t high-risk, there’s no right answer here. Ask around and see if your friends and family members have any recommendations.

Will you find out your due date during your prenatal visit?

Yes, your doctor or midwife will probably calculate your due date when you see them. However, if you like, you can also get a head start on this yourself.

How to calculate when your baby will be born

Determining your estimated due date (EDD) is a simple process. All you need to know is the first day of your last menstrual period (LMP). Pregnancy is generally calculated as lasting 40 weeks from this point, even though conception technically occurs about 2 weeks later.

Here’s how to calculate your approximate due date:

1. Start with the first day of your last menstrual period.
2. Add 280 days (40 weeks) to that date.

For example, if your last period began on January 1, your estimated due date will be October 8. Remember, this is an estimate, and only about 5% of babies are born on their exact estimated due dates. Most births occur within a 2-week range before or after the EDD. 7

More simply, you can plug in your last menstrual cycle dates into a due date calculator or pregnancy tracker and get a due date estimation, too.

A little extra self-care can make a big difference in supporting your health and your baby’s development. Follow these tips:

Take a prenatal vitamin

Taking a prenatal vitamin is very important. A key component in prenatal vitamins is folic acid, which helps prevent neural tube defects during the first few weeks of pregnancy. 8

Look for a prenatal vitamin that contains at least 400 mcg of folic acid, along with other important nutrients like iron, calcium, vitamin D, choline, and omega-3 fatty acids. If morning sickness hits you hard or you just have trouble swallowing pills, consider chewable or liquid options instead.

Eat well and stay hydrated

Eating a balanced diet provides the energy and nutrients you need in your early pregnancy. Focus on adding these nutrient-dense foods to your pregnancy diet:

• Leafy greens and whole grains for folate and fiber
• Lean proteins like poultry, fish, beans, and tofu
• Dairy products or fortified non-dairy alternatives for calcium
• Healthy fat sources like avocados, nuts, and olive oil

Eat small, frequent meals throughout the day to stabilize your blood sugar and reduce your queasiness.

Staying hydrated is just as important as eating right—you need water to support your blood volume (which will increase throughout your pregnancy) and your amniotic fluid production. Try to drink at least eight glasses a day, or more if you’re particularly active or live in a warm climate.

Avoid harmful substances and activities

You probably already know that when you’re pregnant, you need to avoid certain substances and activities that can pose risks to your baby’s development.

• Alcohol: There’s no safe level of alcohol for pregnant women, so make sure to avoid it entirely.
• Smoking and drugs: Both smoking and recreational drugs can increase the risk of complications, including low birth weight, premature birth, and other developmental issues.
• Overheating: Avoid activities that could cause your body to overheat, such as soaking hot tubs, saunas, or intense exercise in hot weather. This can pose a risk to the baby, especially during the early weeks of development.

It’s also important to familiarize yourself with the foods you should avoid during pregnancy if you haven’t done so already.

Manage your early symptoms naturally

Here are a few ways to manage some of the more common symptoms of early pregnancy without resorting to taking medication:

• Bloating: Avoid carbonated beverages and, as mentioned, try eating smaller, more frequent meals. Light exercise, like walking, swimming, or doing prenatal yoga, can also help.
• Nausea: Eat small snacks throughout the day and keep bland foods, such as crackers or toast, on hand. Many women also swear by ginger tea or ginger candy.
• Fatigue: Rest as much as possible, and try to go to bed early. If you’re able to take naps, do so whenever you need.

Overall, just listen to your body and adapt your routine to support it (as well as your growing baby!) There are times when it makes sense to tough it out, but right now, you want to be nice to yourself.

If you’ve been trying to get pregnant, week 4—when you can finally confirm you’re expecting—might be one of the most exciting periods of your life. Remember to breathe!

Some of the less pleasant symptoms of pregnancy, such as fatigue and morning sickness, will probably hit you soon, but with any luck, they’ll come and go before you know it. If you have a partner you can lean on, do that. After all, you’ll never have a better excuse to make them take on extra housework.

Take care of yourself, and do your best to relish this moment. Your baby is still tiny, but she won’t stay that way for long. In just eight months, you’ll meet her for real!