Your Pregnancy Week by Week: A Complete Guide from 1 to 40

Introduction
Welcome to the incredible, transformative journey of pregnancy. Tracking your pregnancy week by week is more than counting down to your due date; it provides a fascinating window into your baby's rapid development and your body's amazing adaptations. This guide walks you through all 40 weeks of pregnancy, explaining what's happening with your baby and the changes you may experience. From the first early signs to the final countdown to meeting your baby, this guide offers evidence-based information, symptom management tips, and reassurance. Whether curious or eager to track milestones, consider this your trusted companion for the next nine months.
The First Trimester: Weeks 1-13
The first trimester is a period of monumental, largely invisible change. It begins on the first day of your last menstrual period, before conception occurs. This foundational period transforms your baby from a tiny cluster of cells into a fully formed, though tiny, human.
Weeks 1-4: Conception and Implantation
During these initial weeks, you are not technically pregnant. Weeks 1 and 2 lead up to ovulation. Conception typically occurs around week 3 when a sperm fertilises an egg, forming a zygote. This rapidly dividing cell bundle becomes a blastocyst that implants into the uterine lining around week 4. Implantation can sometimes cause light spotting, known as implantation bleeding. At this stage, your body starts producing the hormone hCG, which is detectable by home pregnancy tests.
Weeks 5-8: Major Organs Begin to Form
This critical period of embryonic development involves the neural tube (which becomes the brain and spinal cord) beginning to close. The heart starts beating and may be visible via ultrasound around week 6. Tiny buds that will become arms and legs appear. By week 8, all basic organs are in place, though rudimentary.
Key Developments and Early Symptoms
Your body works overtime, producing classic early signs. Fatigue is common as progesterone levels rise. Morning sickness may begin due to hCG. Tender, swollen breasts and frequent urination are typical. Taking prenatal vitamins with at least 400 mcg of folic acid supports healthy neural tube development.
Weeks 9-13: The Embryo Becomes a Fetus
By week 9, the embryo becomes a fetus. The tail has disappeared, and the body begins to straighten. Facial features refine, ears move to their final position, eyelids form, and tooth buds develop. The fetus makes spontaneous movements, though you will not yet feel them. By the end of the first trimester, miscarriage risk drops significantly.
Symptom Management and Your First Prenatal Visit
Nausea and fatigue often peak during this period. If morning sickness prevents you from keeping food or fluids down, consult a doctor online with Apollo24|7. Your first prenatal appointment, usually around weeks 8-10, confirms the pregnancy, estimates your due date, and includes initial blood tests. Apollo24|7 offers convenient home collection for these panels.
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The Second Trimester: Weeks 14-27
Many women find the second trimester the most enjoyable. Early symptoms often subside, energy returns, and a baby bump becomes noticeable. This period is often called the "honeymoon phase" of pregnancy.
Weeks 14-17: The "Honeymoon Period" Begins
The fetus grows rapidly. Lanugo, a fine soft hair, covers the body, and cartilage begins transforming into bone. The fetus can make sucking motions and may find its thumb. For you, energy may increase, appetite returns, and skin may "glow," although some women experience pregnancy acne.
Weeks 18-22: Feeling the First Flutters
During this window, you may feel quickening, the first faint flutters of fetal movement. First-time mothers usually notice this between weeks 18-20. The fetus is now covered in vernix caseosa, a white, protective substance.
The Anatomy Scan: What to Expect
A detailed ultrasound, usually between weeks 18-22, examines the baby's head, abdomen, femur, brain, heart, spine, and organs. Gender may be identified if desired.
Weeks 23-27: Viability and Rapid Growth
By week 24, the fetus reaches "age of viability," meaning survival outside the womb is possible with advanced care. The fetus practices breathing and its senses develop. You may notice more pronounced kicks and jabs.
The Third Trimester: Weeks 28-40+
The final stretch involves the baby gaining weight and refining development for life outside the womb. You may experience increasing physical discomfort and eager anticipation.
Weeks 28-31: Preparing for the Final Stretch
The baby's brain develops rapidly, and it opens and closes its eyes with regular sleep cycles. For you, common symptoms include shortness of breath, heartburn, and Braxton Hicks contractions, which are usually painless and irregular.
Weeks 32-36: Baby Drops and Engages
The baby gains about half a pound a week and likely settles head-down, relieving diaphragm pressure but increasing bladder pressure. Cervical checks for dilation and effacement may begin around week 36.
Common Third-Trimester Discomforts
You may experience swelling in the ankles and feet, backaches, trouble sleeping, and fatigue. Severe or sudden swelling in the face and hands could signal preeclampsia and requires immediate medical attention.
Weeks 37-40+: Full Term and Awaiting Labor
At 37 weeks, pregnancy is full-term. Organs are ready to function independently. Lanugo disappears, and fat stores increase. True labour signs include regular, intensifying contractions, water breaking, and a bloody show. If unsure, consult a doctor on Apollo24|7 for guidance.
Beyond 40 Weeks: What to Expect if You're Overdue
Only about 5% of women deliver on their exact due date. At 41 weeks, pregnancy is considered late; at 42 weeks, postterm. Your doctor will closely monitor the baby with non-stress tests and ultrasounds. Labour induction may be discussed to prevent postterm risks.
Conclusion
The 40-week pregnancy journey is a unique and profound experience, marked by milestones and physical and emotional changes. This week-by-week guide serves as a roadmap for fetal development and maternal changes. Every pregnancy is different; maintain open communication with your healthcare provider, attend prenatal appointments, and listen to your body. Trust your instincts, celebrate each milestone, and seek professional advice when needed. As you approach the final weeks, focus on preparing for childbirth and the joyous arrival of your baby.
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FAQs
Q1. Why are pregnancy weeks counted from the last period?
This method, called gestational age, is used because the exact day of conception is often uncertain. The first day of the last menstrual period is a reliable reference for estimating the due date.
Q2. Is it normal not to feel the baby move every day at 20 weeks?
Yes, particularly for first-time mothers. Consistent daily movements are usually tracked from around 28 weeks, when movements are stronger and more predictable.
Q3. What's the difference between Braxton Hicks and real labour contractions?
Braxton Hicks are irregular, usually painless, and stop with rest or hydration. Real labour contractions become regular, longer, stronger, and closer together, continuing regardless of activity.
Q4. How accurate is a due date?
An estimated due date (EDD) is only that—an estimate. Calculated as 40 weeks from the last period, only about 1 in 20 women deliver on their exact date. Full-term pregnancy ranges from 37 to 42 weeks.
Q5. What should I pack in my hospital bag for delivery?
Pack by 36 weeks. Essentials include ID and insurance information, comfortable clothing, toiletries, phone charger, snacks, a going-home outfit for the baby, and a car seat installed in your vehicle.