Week 4 Pregnancy: The First Formation of Your Baby

In Week 4 of pregnancy, your baby is starting to form. The fertilised egg has implanted in the uterine lining and is now called an embryo. During this crucial stage, the embryo begins to develop and take shape, laying the foundation for future growth. You may start to experience early pregnancy symptoms such as nausea, fatigue, and tender breasts. This week is significant as your body and baby undergo rapid changes, marking the true beginning of your pregnancy journey.

Curious about how fertilisation happened? Discover the journey of conception and early cell division in week 3 of pregnancy, when your baby first begins developing.

Week 4 body changes

At this stage, you may notice a missed period, indicating the early signs of pregnancy. The placenta continues to develop, increasing the production of human chorionic gonadotropin (hCG), the hormone crucial for pregnancy.

hCG signals the ovaries to cease the monthly release of egg cells, effectively stopping your period. In the first month of pregnancy, the embryo further embeds itself into the lining of the uterus. The bodily changes you experience may resemble premenstrual symptoms, as this is the time when you would typically expect your period.

During this week, your body is undergoing significant changes, and you may experience symptoms similar to premenstrual syndrome (PMS).

Week 4 pregnancy symptoms

Some of the pregnancy symptoms you'll experience in the fourth week are similar to those of premenstrual syndrome (PMS), and since your period is due soon, they can easily be mistaken for each other. These symptoms include:

• Tiredness
• Nausea
• Aching and tingling breasts
• Morning sickness (which can happen at any time of the day)
• Metallic taste in your mouth
• Constipation
• Increased frequency of urination
• Increased bloating or gas

Your baby at week 4

At 4 weeks pregnant, your baby's brain and heart are starting to develop. Blood vessels are forming, and circulation is beginning. The umbilical cord, which will connect your baby to you, is also starting to grow. Let's take a closer look!

The embryo has three layers that will become different parts of your baby's body:

1. The endoderm will develop into the digestive system, pancreas, liver, and lungs.
2. The mesoderm, the middle layer, will form the muscles, skeleton, heart, and blood vessels.
3. The ectoderm, the outer layer, will turn into the skin, teeth, and nervous system.

At this stage, the amnion sac and yolk sac also begin to form. These structures protect the embryo and provide blood until the placenta is fully developed. This intricate process ensures your baby has the necessary support for healthy growth.

Testing for pregnancy 

Your hCG levels (the pregnancy hormone) are now high enough to test for pregnancy using a home test kit or by visiting your doctor. If you tested during week three and got a negative result, try again now, especially if you’ve missed your period. Detailed tests like blood tests and ultrasounds to check for conditions such as Down syndrome and Trisomy usually happen later in the first trimester, but it's good to start your prenatal care early.

Most obstetricians and gynaecologists suggest waiting until at least 6 weeks for the first visit, but it’s better to come in sooner for early prenatal care.

When should you see a doctor to confirm your pregnancy?

Discovering you're pregnant is an exciting moment, but it's essential to know when to seek professional medical care. If you've taken a home pregnancy test and received a positive result, here's guidance on when to consult a doctor:

1. After a positive home test

   • Generally, wait about a week before booking an appointment with a gynaecologist. This allows time for the pregnancy to be visible on an ultrasound scan, typically around 6-7 weeks of gestation.

   • If you have irregular menstrual cycles, consider seeing a doctor sooner to confirm the pregnancy and assess its viability.

2. Immediate medical attention

   • Seek medical care promptly if you experience any unusual symptoms such as vaginal bleeding, severe abdominal pain, or extreme nausea, regardless of how far along you think you are.

At Thomson Medical, we understand the importance of timely and comprehensive prenatal care. Our team of obstetricians and gynaecologists at Thomson Specialists and Thomson's Women Clinic are here to support you from the moment you suspect you're pregnant. Remember, every pregnancy is unique, and our team is here to address your individual needs and concerns.

Request an appointment with Thomson Medical today to begin your pregnancy journey with compassionate care and support.

Curious about what’s next in the upcoming weeks? Read more about the formation of your baby in week 5!

FAQ

What are the recommended tests and screenings for 4 weeks of pregnancy? 

At 4 weeks of pregnancy, the primary focus is on confirming the pregnancy. Here are the typical tests recommended:

• Home pregnancy test 

  • This test checks for the presence of the hormone hCG in urine, which indicates pregnancy. It is most reliable after a missed period.

• Blood test for hCG

  • A blood test can detect pregnancy earlier than a urine test and measure the precise levels of hCG, which can provide insight into the health of the pregnancy.

While these initial tests are fundamental at 4 weeks pregnant, more comprehensive screenings and scans typically begin after week 6. These later tests include ultrasounds, blood type testing, and urine analysis, which help confirm the pregnancy's health and progression. 

Is it normal to bleed at week 4 of pregnancy? 

Light bleeding or spotting can be relatively common at week 4 of pregnancy. However, it's important to understand the possible reasons and consult with your obstetrician/gynaecologist if you have concerns. Some of the reasons might include: 

• Implantation bleeding

  • Light spotting as the fertilised egg embeds into the uterine lining.

• Hormonal changes

  • Hormonal shifts in early pregnancy can cause light bleeding or spotting.

• Cervical changes

  • Increased cervical blood flow can cause light bleeding, especially after intercourse or a pelvic exam.

• Subchorionic haemorrhage 

  • Bleeding between the gestational sac and uterine wall, usually detected via ultrasound.

• Early pregnancy loss

  • Heavier bleeding with cramping and tissue passage, possibly indicating miscarriage; consult a doctor.

The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Book an appointment with Thomson Medical today.