4 weeks pregnant? Baby development milestones, symptoms, tips, & more

Shweta Das

Created by Shweta Das
Updated on Feb 17, 2022

4 weeks pregnant Baby development milestones symptoms tips more

At 4 weeks, you’re about to complete the first month of your pregnancy.

Your baby is settling deeper into your uterine lining and your body is beginning a series of changes to support your baby’s development over the next 36 weeks, give or take a few. 

At 4 weeks pregnant, one of the earliest symptoms that you could experience is a missed period. It’s interesting to note that while your egg may have been fertilized in the last 2 weeks, your pregnancy start date is calculated from the start of your last menstrual period. 

At this time, the levels of progesterone hormone increase in your system to sustain your pregnancy. You can usually get a clear positive if you take a urine pregnancy test now.

As your baby develops, your body also starts producing more and more human chorionic gonadotropin (hCG). This hormone appears in your blood within 7-11 days after conception. It is formed by the cells that eventually turn into the placenta. 

Here’s more information about your baby’s growth, the symptoms you may experience, and the tips you could follow at 4 weeks pregnant.

How big is your baby at 4 weeks pregnant?

At 4 weeks pregnant, your baby is microscopic in size--smaller than a poppy seed. 

In the 4th week of your pregnancy, your baby is a collection of cells known as a blastocyst. This tiny ball of cells experiences rapid development this week and preps for all the crucial development it will undergo in the next 6 weeks. 

By the end of the 4th week of your pregnancy, around half of the blastocyst cells will form an embryo, smaller than a poppy seed in size. The other half of the cells will turn into the amniotic sac and work to keep your baby safe and provide nourishment for his/her growth.

It is interesting to note that while your baby is incredibly small at this stage, a lot of his/her traits, such as eye color, hair color, and sex, have already been determined by the chromosomes.

How fast is your baby growing at 4 weeks pregnant?

At 4 weeks pregnant, your baby is growing fast:

  • The cells start multiplying quickly and taking up different functions. Over the next 6 weeks, the two layers of your embryo, the hypoblast, and the epiblast will begin to develop into all the organs of your baby. 

  • Your body starts adapting to provide more nourishment to your baby. Your embryo’s outer cells tunnel into your uterine lining and spaces start forming within this layer for your blood to flow in so that nutrients and oxygen can reach your growing baby.

  • The amniotic sac containing amniotic fluid encloses your baby and will cushion them as they grow. The yolk sac will develop your baby's first red blood cells and blood vessels.

Does your baby have a heartbeat at 4 weeks pregnant?

Your baby, a little blastocyst at this stage, doesn’t have a heartbeat yet. 

At 4 weeks pregnant, your baby starts developing a blood vessel, which, over the coming weeks, will form the heart and the circulatory system. While the heart will continue to grow until Week 10, it could start beating as soon as Week 5 or 6.

Symptoms at 4 weeks pregnant

At 4 weeks pregnant, you may not notice many changes in your body. You may not even realize that you’re pregnant if you haven’t kept a close track of your menstrual cycle or if your periods are irregular. However, increased levels of hormones can cause you to experience some of the more common pregnancy symptoms at 4 weeks.

While most early symptoms of pregnancy don't start until around Week 6, you could experience the following symptoms at 4 weeks pregnant: 

Tender or swollen breasts

Breast tenderness or soreness could be one of the early signs of pregnancy. You may experience this around Week 4 to Week 6 and it could last through the first trimester. 

At 4 weeks pregnant, you could also notice the following changes: 

  • Your breasts grow bigger or heavier 

  • Your nipples darken

  • Some prominent blue or purple veins develop on your breasts


Extreme tiredness or exhaustion is one of the most common symptoms at 4 weeks pregnant. It most likely occurs due to the rapid increase in progesterone levels during early pregnancy. It affects nearly all expecting mothers in the first trimester. 


At 4 weeks pregnant, you could experience mild cramps. These implantation cramps occur as your fertilized egg implants deeper in the lining of your uterus. However, severe cramping or pain along with bleeding during early pregnancy could be a sign of something serious, such an ectopic pregnancy or a miscarriage. Consult your doctor in such a case, if only to rule out any problems.

Bleeding or spotting

You could also get light bleeding along with cramps during Week 4 of your pregnancy. This pregnancy discharge is a result of implantation and is completely normal. However, consult your doctor if:

  • If you experience heavy bleeding, like a period or even heavier

  • If the bleeding lasts longer than a couple of days

  • If you’re worried for any reason about the bleeding

Gas or bloating

Increased progesterone levels at 4 weeks pregnant could also slow down your digestion. This results in gas, bloating, or a feeling of discomfort in your gut. 

Mood swings

You could experience mood swings at 4 weeks pregnant. These could occur due to increased levels of hormone, stress, or exhaustion. Mood swings could get intense during the first trimester. It is better to consult your doctor if your mood swings: 

  • Get more frequent or intense

  • Last longer than 2 weeks

Nausea or vomiting

Morning sickness could hit you any time of the day. While it usually begins when you’re around 6 weeks pregnant, you could have it as early as 4 weeks. You could experience just nausea, or have vomiting along with it. 

You could also develop the following at 4 weeks pregnant:

  • A heightened sense of taste or smell

  • Food aversions or cravings

Note: The symptoms that you may experience at 4 weeks pregnant are often similar to regular premenstrual symptoms and you may feel like you’re about to start your period.

Symptoms if you’re 4 weeks pregnant with twins

If you’re carrying twins, your first trimester symptoms may get amplified. You’re more likely to have higher levels of hCG, progesterone, and other hormones, and you could even suspect you’re pregnant sooner than others. 

At 4 weeks pregnant, you can’t determine the number of babies you’re carrying or see anything on an ultrasound. However, high hCG and progesterone levels could indicate that you’re carrying twins or multiples. You will be able to confirm this at your first prenatal appointment with your Doctor, which is usually around Week 8. This appointment could be scheduled earlier if you had fertility treatment.

Learn more about twin pregnancy symptoms here.

What’s your belly like at 4 weeks pregnant?

While you most likely don’t look pregnant yet, your 4 week pregnant belly might feel a little bloated. 

At this stage, you need to take care of yourself and your baby. 

Your baby is already rapidly developing at 4 weeks, and needs all the nourishment for his/her proper growth. If you’re not already, start taking a prenatal vitamin with folic acid in consultation with your Doctor. Folic acid is known to help prevent birth defects in developing babies.

Also, as your pregnancy progresses, try wearing looser clothes to feel more comfortable in your daily routine.


Tips to relieve symptoms at 4 weeks pregnant 

If you’re experiencing the early symptoms of pregnancy, follow these home remedies to get some relief:

  • If you’ve got tender or sore breasts, try wearing a supportive bra during the day and to bed.

  • If you feel exhausted, try going to bed early and taking a nap during the afternoons. Exercises like walking and prenatal yoga can also help increase your energy levels.

  • If you experience frequent urination, try to moderate your fluid intake. However, don’t cut back too much, because you need to stay hydrated during pregnancy.

  • If you’re nauseous, gaseous, or bloaty, or you feel discomfort in your gut:

    • Eat small, frequent meals throughout the day.

    • Eat slowly and chew well.

    • Avoid food that triggers nausea or bloating.

    • Don't drink too much water during meals.

    • Avoid carbonated beverages, gum, and sorbitol (artificial sweetener).

    • Do exercises like go on walks and practice prenatal yoga. 

    • Snack on carbohydrates and tarty foods if that helps.

    • Wear comfy clothes.

While these are general guidelines, in case you have specific queries regarding your pregnancy or your baby’s development, ask our expert panel of Doctors for advice.

Things to avoid at 4 weeks pregnant

At 4 weeks pregnant, your baby is most vulnerable to anything that could affect his/her development. To prevent any growth and development issues, avoid the following during this time:

  • Alcohol

  • Smoking

  • Drugs

  • Unsafe chemicals

  • Medicines that are not pregnancy-safe

  • Overheating

While these are broad guidelines, in case you have specific concerns about your pregnancy or your baby’s growth, ask our Doctors for advice.

When to Consult a Doctor

When your pregnancy test is positive and your pregnancy is confirmed, schedule your first prenatal appointment at your Doctor’s. 

If you just realized that you could be pregnant, use a home pregnancy test kit to confirm your pregnancy. For the most accurate results, wait until a few days after you miss your period and use the first pee of the morning for the test since the hCG levels are the most concentrated then.

For a prenatal appointment

Usually, you should schedule your first prenatal visit within 8 weeks of your last menstrual period. However, this should be arranged earlier if you have a medical condition, have had pregnancy problems in the past, or are experiencing symptoms such as vaginal bleeding, abdominal pain, or severe nausea and vomiting.

In case of a possible miscarriage

In Week 4, a miscarriage is known as a chemical pregnancy. This is because the embryo cannot be detected by ultrasound. It is only detectable through blood and urine testing.

While you shouldn’t worry about it, it is important to know that the rate of miscarriages is high in early pregnancy, many of which happen around the time a woman expects her period to start.

The best way to gauge what’s going on is to keep a track of your body changes and speak with your doctor about your symptoms.

Signs of a miscarriage include: 

  • Cramping

  • Spotting

  • Heavy bleeding

Experiencing these symptoms doesn’t necessarily mean that you need to fear the worst. You could also have spotting, bleeding, or a feeling of discomfort as the blastocyst buries deeper into your uterine lining during early pregnancy. 

What’s next?

Now that you’re 4 weeks pregnant and are well-versed with what’s on hand, check out the sections below.

Know more about what to expect throughout your pregnancy.

Get a quick look at what’s in store for you in the coming months with our day-by-day pregnancy calendar.

Calculate your estimated due date.

Use our Baby Due Date Calculator to determine your expected due date. This free tool predicts your due date based on the date of your last period and the length of your typical menstrual cycle. 

Remember that your expected due date is just an estimate and you could deliver any day a week or two before or after. 

Consider antenatal screening for genetic disorders

You could take simple blood- or saliva-based antenatal screening test to check whether your baby is at risk of getting any genetic disorders, such as cystic fibrosis or sickle cell disease.


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