Author & Reviewer Dr. Anuja Dokras, MBBS, DNB (Obs & Gynae)
Oxford-trained specialist in Infertility & Women’s Health.
Founder of LMP Calculator.
“The fourth week of pregnancy is an exciting time. This is the week when your period is due and the first reliable signs of pregnancy appear. In this guide, we will explore what is happening inside your body during this decisive week and which symptoms you should pay close attention to.”
Introduction: Why is the Fourth Week of Pregnancy So Important?
First, it’s essential to understand how doctors count the fourth week of pregnancy. It is the fourth week from the first day of your Last Menstrual Period (LMP). This means it is the time approximately 2 weeks after conception (fertilization).
This week is crucial because:
- Implantation is complete: The embryo is now securely attached to the uterine wall.
- hCG hormone levels are rising rapidly: This is the hormone that pregnancy tests detect.
- Your period is due: This is the week when your period will either arrive or be missed.
Part 1: The Biggest and Most Definitive Sign of Week 4
1. A Missed Period
- What It Is: If you have a regular menstrual cycle, missing your period this week is the clearest and most reliable sign of pregnancy.
- The Science Behind It: After implantation, your body begins producing the hormone hCG (Human Chorionic Gonadotropin). This hormone signals the ovaries to continue producing progesterone, which prevents the uterine lining from shedding, and thus, your period does not arrive.
Doctor’s Advice: “If your period does not arrive on its due date, this is the best time to take a pregnancy test. It is the most decisive sign of this week.”
Part 2: What’s Happening Inside Your Body in Week 4?
This week, the embryo that was just a cluster of cells a few days ago is now deeply nestled into your uterine lining.
- Embryo’s Development: It is now dividing into two layers: the epiblast and the hypoblast, which will eventually form all of the baby’s organs and body parts.
- Formation of the Amniotic Sac and Yolk Sac: These supportive structures, which will nourish and protect your baby throughout the pregnancy, are also beginning to form.
- Production of hCG: The early placenta cells are rapidly releasing the hCG hormone into your bloodstream, triggering the onset of pregnancy symptoms.
Part 3: Other Symptoms You Might Feel in Week 4
Due to the rising levels of hCG and progesterone, you may begin to experience the following symptoms:
2. Mild Abdominal Pain or Cramping
- How It Feels: You might feel light cramping or a pulling sensation in your lower abdomen. This often feels similar to period cramps but is usually milder.
- The Science Behind It: This can be due to the uterus expanding and reacting to the implantation of the embryo.
Expert Opinion – Dr. Anuja Dokras: “Mild cramping is normal, but if the pain is severe, concentrated on one side, or accompanied by heavy bleeding, it could be a sign of an ectopic pregnancy, and you should contact your doctor immediately.”
3. Fatigue
- How It Feels: You may feel much more tired than usual, even if you are getting enough sleep.
- The Science Behind It: This fatigue is caused by high levels of progesterone and the extra work your body is doing to support the embryo.
4. Breast Tenderness
- How It Feels: Your breasts may feel swollen, heavy, or painful to the touch. This symptom may become more pronounced than it was in the previous week.
5. Early Nausea (“Morning Sickness”)
- How It Feels: You might start to feel a slight queasiness or nausea at any time of day, but especially in the morning. Certain smells can make it worse.
6. Bloating
- How It Feels: The progesterone hormone can slow down your digestion, making you feel bloated and gassy, much like you might before your period.
Part 4: Your Action Plan: What to Do in Week 4
1. Take a Home Pregnancy Test
- The Time is Right: Since your period is now officially missed, the hCG levels in your urine should be high enough for a home test kit to easily detect them. Use your first-morning urine for the most accurate result.
- What a Positive Result Means: A positive result means you are almost certainly pregnant.
2. Contact Your Doctor
- Once you have a positive home test, call your doctor to schedule your first prenatal appointment. The doctor can confirm the pregnancy with a blood test and guide you on the next steps.
3. Start Healthy Habits
- If you haven’t already, now is the perfect time to start taking a prenatal vitamin with folic acid.
Conclusion: The Start of a New Journey
Dr. Anuja Dokras’s Final Message:“Week 4 marks the official start of your pregnancy journey. A missed period and a positive pregnancy test are the first concrete proofs you’ve been waiting for. Embrace these early symptoms, as they are signs that your body is doing something amazing. Now is the time to prioritize your health and seek professional medical care.”
Disclaimer: This article is for general informational purposes only and should not be considered a substitute for professional medical advice. Always consult your doctor or another qualified health provider with any health concerns.