Week 5: The Heart Beats

A magical week! The tiny heart begins beating at around 80 beats per minute. It may be the most moving moment in early pregnancy — inside your body, a tiny heart is beating for the very first time.

At the same time, the nervous system is developing rapidly, and the first hints of arms and legs are appearing. Your baby is the size of a sesame seed — only about 2 millimeters long — but an incredible amount is happening in there. Three cell layers are working at full speed to build the foundation for all the organs.

This week also marks the start of a period of many physical changes for you. Morning sickness, fatigue, and tender breasts are common companions over the coming weeks. For many, this is the week they take a pregnancy test and get confirmation. You are officially pregnant — congratulations!

Baby's Development

The embryo is developing at an impressive pace this week:

Heart beats: The primitive heart tube begins to pulse at about 80 beats per minute. It will increase to over 150 in the coming weeks
Neural tube forms: The foundation for the brain and spinal cord is under development. Folic acid is essential for this process
Arm and leg buds: Small protrusions that will become arms and legs begin to grow from the body
Three cell layers: The embryo now has ectoderm (skin and nerves), mesoderm (muscles and skeleton), and endoderm (organs)
Placenta develops: The placenta and umbilical cord are forming and will soon take over nutrient supply from the yolk sac
Facial structures begin: The very first structures of the eyes, nostrils, and mouth start to take shape as small indentations and folds
Circulatory system: The first blood vessels form and connect the embryo to the uterine wall
Size: The embryo measures about 2 mm from crown to rump, roughly the size of a sesame seed

What Is Happening With the Nervous System?

The neural tube is one of the very first structures to form. It starts as a flat sheet of cells that folds into a tube. The upper part becomes the brain, and the lower part becomes the spinal cord.

The neural tube closes over the next two to three weeks, and this is why folic acid is critically important right now. According to WHO and ACOG, women should take 400 micrograms of folic acid daily from when they plan to conceive and throughout the entire first trimester. Folic acid reduces the risk of neural tube defects such as spina bifida by up to 70 percent. If you have not started folic acid yet, it is not too late — start today.

The First Heartbeat

The heart is the first organ to start functioning in the embryo. In week 5, it is not yet a complete heart but a simple tube that pulses rhythmically to pump blood through the tiny body. This primitive heart tube will over the coming weeks fold and divide into four chambers.

The heartbeat can sometimes be seen on an early ultrasound from week 6, and it is one of the most reliable signs of a viable pregnancy. The tiny heart will continue to beat faster and faster, reaching over 150 beats per minute by weeks 8–9.

Your Body

Morning sickness: Many people start to feel nauseous now. It can come at any time of day, not just in the morning
Tender breasts: Breasts may feel swollen, tender, and heavier than usual due to increased blood flow and hormonal changes
Fatigue: An overwhelming tiredness is completely normal. The body is using enormous energy to build the placenta and support the embryo
Heightened sense of smell: Many pregnant people find their sense of smell becomes much stronger, which can intensify nausea
Bloated feeling: Even though the bump is not visible yet, you may feel bloated and tight in your clothes
Mood swings: hCG, progesterone, and estrogen are rising rapidly and can cause emotional swings
More frequent urination: Even in week 5, increased blood flow to the kidneys can mean more trips to the bathroom

Hormones in Week 5

The hormone hCG (human chorionic gonadotropin) is what makes the pregnancy test positive. It roughly doubles every 48 hours in early pregnancy and is the main cause of morning sickness. Progesterone keeps the uterine lining intact and is important for supporting the pregnancy. Estrogen stimulates growth of the uterus and breasts.

hCG levels in week 5 are typically between 18 and 7,340 mIU/ml, but values vary greatly from person to person. The most important thing is that the level rises steadily, not the exact number. Your midwife or doctor can take blood tests to monitor this if needed.

Good to Know

Morning sickness affects about three in four pregnant people. It is uncomfortable, but actually a good sign — it means the hormones are doing their job. Nausea is usually worst between weeks 6 and 12 and eases for most people after the first trimester.

Small, frequent meals can help. Try to eat a little before getting out of bed in the morning. Dry crackers, toast, or nuts can ease nausea. Ginger tea or ginger capsules are also a safe option recommended by major health bodies.

Remember that folic acid is especially important right now. The neural tube closes over the coming weeks, and adequate folate intake significantly reduces the risk of spina bifida. Folic acid is found naturally in dark green vegetables, citrus fruits, beans, and legumes, but supplements are also recommended.

It is also completely normal to feel ambivalent or worried at first. Many feelings are in play, and it is okay to take time to process the news. Talk to someone you trust if you need to.

Exercise is still safe and recommended in early pregnancy. Take walks, swim, or do yoga — moderate activity is good for both you and the baby. Avoid contact sports and activities with a high risk of falling.

Folic Acid and Supplements

Folic acid is the single most important supplement in early pregnancy. According to WHO and ACOG, all people who are pregnant should take 400 micrograms of folic acid daily throughout the entire first trimester.

Why Is Folic Acid So Important?

Folic acid (vitamin B9) is essential for cell division and the development of the neural tube — the structure that becomes the baby's brain and spinal cord. The neural tube closes between weeks 5 and 7, and a deficiency of folic acid during this period increases the risk of neural tube defects such as spina bifida and anencephaly.

Other Important Supplements

According to WHO and ACOG, these supplements are recommended for pregnant people:

Folic acid: 400 micrograms daily through the entire first trimester
Vitamin D: 10–15 micrograms (400–600 IU) daily throughout pregnancy — especially important when sun exposure is limited
Iodine: Important for the baby's brain development. Found in dairy products, fish, and iodized salt. Many pregnant people do not get enough iodine through diet alone
Iron: Iron needs increase through pregnancy. Your midwife checks iron levels at prenatal appointments

You do not need to buy expensive prenatal supplements. A simple folic acid supplement and vitamin D are sufficient for most people. Talk to your midwife or doctor about your individual needs.

Prenatal Care — What to Expect

In week 5 it is too early for the first prenatal appointment, but you should:

Book an appointment with your doctor or midwife for confirmation of pregnancy and planning of care
Continue with folic acid — 400 micrograms daily (WHO recommendation)
Avoid alcohol, tobacco, and drugs — no amount of alcohol has been shown to be safe in pregnancy according to CDC and WHO
Check your medication list — some medications are not safe during pregnancy. Contact your doctor before stopping any regular medications

The first prenatal appointment with your midwife or doctor is usually between weeks 8 and 12. At this appointment, blood tests are taken, blood pressure is measured, and you receive information about pregnancy. Most healthcare systems provide prenatal care for all pregnant people.

Use the due date calculator to estimate your expected delivery date based on the first day of your last period.

Diet and Nutrients

Key Nutrients in Week 5

Folic acid: 400 micrograms daily. Most important right now for neural tube development
Iron: Iron needs increase early. Good sources include lean meat, beans, and dark leafy greens
Vitamin D: 10–15 micrograms daily throughout pregnancy
Iodine: Important for the baby's brain development. Found in dairy products, fish, and iodized salt
Water: Drink at least 1.5 liters daily to support the increased blood production

Foods to Avoid

Pregnant people should avoid:

Alcohol in any amount
Raw and undercooked meat (risk of toxoplasmosis)
Soft and mold-ripened cheeses (risk of listeria)
Refrigerated smoked and cured fish (risk of listeria)
Liver and pâté in large amounts (too much vitamin A)
Fish with high mercury content (shark, swordfish, king mackerel, large tuna)

Good Food Choices in Early Pregnancy

These are good foods for pregnant people:

Lean meat and fish (well-cooked)
Eggs (fully cooked)
Pasteurized dairy products
Whole grain products, bread, and oatmeal
Fruit and vegetables (at least five portions daily)
Beans, lentils, and other legumes
Nuts and seeds (good sources of healthy fats)

For Your Partner

Show understanding for fatigue and nausea — it is not laziness, it is hard work the body is doing
Help with cooking, especially if food smells trigger nausea
Be a good listener — early pregnancy can bring up many feelings
Offer to make breakfast in bed, especially on days with a lot of nausea
Read up on pregnancy — understanding makes it easier to be supportive
Be prepared that your partner may need much more sleep than usual

Tips for Week 5

Eat often and in small amounts: Small meals every two to three hours can keep nausea at bay
Keep snacks by the bed: Dry crackers or toast before getting up can ease morning sickness
Rest when your body signals it: Fatigue is nature's way of telling you your body needs extra rest
Try ginger: Ginger tea, ginger capsules, or ginger biscuits are safe and can ease nausea
Start folic acid: If you have not already — start today. It is the most important supplement in early pregnancy
Follow the pregnancy: Check the pregnancy timeline to follow the baby's development week by week

When to Contact a Doctor

Contact your doctor or midwife if you experience:

Severe vomiting making it impossible to keep food or fluids down (may be hyperemesis)
Bleeding that increases in amount or is bright red
Severe, cramping abdominal pain, especially on one side (may indicate ectopic pregnancy)
Dizziness or fainting
Fever over 38°C (100.4°F)

Light spotting or brownish discharge in early pregnancy is fairly common and often results from the embryo attaching to the uterine lining (implantation bleeding). It is usually harmless, but contact your doctor for reassurance.

Seek urgent medical care if you have severe one-sided abdominal pain, as this may be a sign of ectopic pregnancy. This is an acute condition requiring prompt medical evaluation.

Did You Know?

The tiny heart now beating for the first time is no bigger than a poppy seed! It starts at about 80 beats per minute and will increase to over 150 beats per minute within a few weeks.
Your baby now has three cell layers developing into completely different parts of the body: ectoderm (skin, hair, nails, brain), mesoderm (heart, muscles, skeleton), and endoderm (lungs, liver, digestion).
The neural tube, which is the precursor to the brain and spinal cord, closes during the coming weeks. This is why folic acid is so important right now!
Morning sickness affects about 75 percent of all pregnant people, and despite its name it can come at any time of day. Researchers believe it is linked to rising hCG hormone levels.
In week 5, the embryo still gets all its nutrition from the yolk sac. The placenta gradually takes over this role over the coming weeks.
Your embryo is growing at about 1 millimeter per day this week. That sounds small, but it means it doubles in size in just a few days!

Frequently Asked Questions About Week 5

Is it normal to have no morning sickness?

Yes, absolutely! About 25 percent of pregnant people experience little or no nausea, and this does not mean anything is wrong with the pregnancy. Every body responds differently to pregnancy hormones. Absence of nausea is not a sign that the pregnancy is not developing normally.

Can I keep exercising as normal?

Most people can continue with their usual exercise routine in early pregnancy, with some adjustments. Avoid contact sports and activities with a high risk of falling. Moderate exercise such as walking, swimming, and yoga is safe and recommended by major health bodies. Listen to your body and reduce intensity if you feel tired or nauseous.

Is it dangerous to eat little because of nausea?

In early pregnancy the baby is very small and needs minimal nutrition. Nausea is uncomfortable for you, but the baby does fine even if you do not eat optimally for a few weeks. The most important thing is to stay hydrated. Eat what you can — even if it is just dry crackers and water. Contact your doctor if you cannot keep fluids down for more than 24 hours.

Should I tell anyone I am pregnant already?

It is entirely up to you. Many wait until after week 12, when the risk of miscarriage is lower. But some choose to tell close friends or family early, especially to have someone to talk to if they need support. There are no rules here — do what feels right for you.

Can the pregnancy test show the wrong result in week 5?

A positive pregnancy test is almost always correct. False positives are extremely rare. hCG levels are usually high enough to give a positive result from the day the period is missed, around weeks 4–5. If you get a negative result but suspect you might be pregnant, wait a few days and test again — hCG levels may still be too low.

When can I see the baby on an ultrasound?

The earliest ultrasounds are usually done between weeks 6 and 8, but many prenatal care systems do not offer routine ultrasound until weeks 11–14 (first trimester screening). If you have had complications in previous pregnancies, your doctor may order an early scan. In week 5, the embryo is often too small to see clearly.

What is the difference between counting pregnancy weeks from the last period and from fertilization?

Pregnancy weeks are counted from the first day of the last menstrual period, not from the date of fertilization. This means that in week 5 you are only about 3 weeks past fertilization. This counting method is used because most people remember the date of their last period, while the exact date of fertilization is rarely known. Use the due date calculator to calculate your exact due date.

What are the most common signs of pregnancy in week 5?

The most common signs of pregnancy in week 5 are:

Missed period
Nausea (can start already now)
Tender and swollen breasts
Fatigue and increased need for sleep
More frequent urination
Light spotting (implantation bleeding)
Mood swings
Heightened sense of smell

Many of these symptoms resemble PMS, and that is why a pregnancy test is the only reliable way to confirm pregnancy.

Is it safe to take paracetamol (acetaminophen) in pregnancy?

Paracetamol (acetaminophen) is considered the safest pain reliever during pregnancy. It can be used for headache, fever, or other pain. Use the lowest dose possible for the shortest time necessary. Ibuprofen should be avoided in pregnancy, especially in the third trimester. Always talk to your doctor or pharmacist before taking other medications.

Next week: The face begins to take shape with nostrils, eye lenses, and ear canals!