Your complete pregnancy week by week guide — from week 1 through week 40. Dr. Sanjana L, a leading gynaecologist in HSR Layout & Attibele, walks you through fetal development, weekly symptoms, scans, antenatal checkup schedules and warning signs at every stage of pregnancy.
Pregnancy Week by Week Guide — From Week 1 to Week 40
Pregnancy is one of the most extraordinary journeys a woman can experience. Across 40 weeks, a single fertilised cell becomes a fully formed baby — while your body adapts in ways you never imagined.
This comprehensive pregnancy week by week guide is written by Dr. Sanjana L (MBBS, MS OBG, Gold Medalist, FRM RGUHS, FMAS), a trusted pregnancy doctor in HSR Layout and pregnancy doctor in Attibele, with over 10 years of obstetric experience at Health Nest and Raghava Multispeciality Hospital. It is designed for expecting mothers across Bangalore — HSR Layout, Sarjapura, Electronic City, Koramangala, Attibele, Chandapura and beyond — who want a clear, week-by-week roadmap of pregnancy care in HSR Layout and Attibele.
For a deeper dive into the early weeks, read Dr. Sanjana's first trimester pregnancy guide and early signs of pregnancy before missed period guide.
How Pregnancy Is Dated
Pregnancy is dated from the first day of your last menstrual period (LMP), not from the day of conception. This is because most women know the date of their last period but not the exact day of ovulation. So the first 2 weeks of your "pregnancy" actually pass before conception even occurs.
A full-term pregnancy lasts about 40 weeks (or 280 days) from LMP, divided into three trimesters:
- First trimester: Weeks 1 to 12
- Second trimester: Weeks 13 to 27
- Third trimester: Weeks 28 to 40+
First Trimester (Weeks 1 to 12) — Building Foundations
The first trimester is when most fetal development happens. By the end of week 12, all major organs have formed. This is also when most early antenatal checkups in HSR Layout and antenatal checkups in Attibele start.
Week 1 and 2: Pre-Conception
Your body is preparing for ovulation. The uterine lining thickens. Egg release (ovulation) typically occurs around day 14 of a 28-day cycle. Conception happens within 24 hours of ovulation, when sperm meets egg in the fallopian tube. Tip: Start folic acid 400 to 800 mcg daily if you are trying to conceive.
Week 3: Fertilisation
The fertilised egg (zygote) divides as it travels down the fallopian tube. Genetic blueprint is set — sex, eye colour, hair, height. You will not feel anything yet.
Week 4: Implantation
The blastocyst implants into the uterine lining. hCG production begins. You may notice implantation bleeding (light spotting) or mild cramps. A home pregnancy test typically becomes positive at the very end of this week.
Week 5: Heart Begins to Form
The embryo is the size of a sesame seed (around 2 mm). The neural tube (future brain and spinal cord) is forming. Pregnancy symptoms — sore breasts, fatigue, frequent urination, nausea — may start. Book your first antenatal checkup in HSR Layout or Attibele this week.
Week 6: First Heartbeat
The embryo is about 5 mm. Tiny limb buds appear. The first heartbeat is sometimes detectable on a high-quality transvaginal pregnancy scan in HSR Layout. Morning sickness peaks for many women.
Week 7: Limbs Lengthen
The embryo is around 1 cm. Eyes, nostrils and ears begin to take shape. Many women experience strong food aversions and exhaustion.
Week 8: Baby Looks Like a Baby
The embryo (now called a fetus) is around 1.5 cm. Fingers and toes are forming. Heartbeat is now consistently visible on pregnancy ultrasound in HSR Layout. The first formal dating scan is usually done now.
Week 9: Major Organs Forming
The fetus is around 2.3 cm. All major organs are present in early form. The placenta is taking over hormone production from the corpus luteum.
Week 10: External Genitalia Develops
The fetus is around 3 cm. External genitalia begin to form (still not visible on ultrasound). Nausea may start to ease for some women.
Week 11: Movement Begins
The fetus is around 4 cm and starts making small movements (you cannot feel them yet). Bones are beginning to harden.
Week 12: First Trimester Ends
The fetus is around 5.5 cm and weighs about 14 grams. The NT (nuchal translucency) scan and dual marker test is done between week 11 and 13 weeks 6 days to screen for chromosomal abnormalities (Down syndrome). Risk of miscarriage drops sharply after week 12.
Second Trimester (Weeks 13 to 27) — The Golden Period
The second trimester is often called the most enjoyable phase of pregnancy. Energy returns, nausea usually subsides, and the bump starts to show. Most women in prenatal care in HSR Layout report feeling their best between weeks 14 and 24.
Week 13: Vocal Cords Form
The fetus is around 7 cm. Vocal cords develop. Many women feel a noticeable energy boost.
Week 14: Facial Expressions Begin
The fetus is around 8 cm. It can squint, frown, and grimace. The thyroid gland begins producing its own hormones.
Week 15: Hair Follicles Appear
The fetus is around 10 cm. Hair patterns and skin pigment begin developing. Some women notice darkening of the linea nigra (line down the abdomen).
Week 16: Sex Visible on Ultrasound
The fetus is around 12 cm. External genitalia are now developed enough to potentially identify sex on ultrasound (note: prenatal sex determination is illegal in India under the PCPNDT Act).
Week 17: Skeleton Hardens
The fetus is around 13 cm. Bones transform from cartilage to actual bone. The umbilical cord thickens.
Week 18: First Movements (Quickening)
First-time mothers may feel "quickening" — the first faint flutters of fetal movement — between weeks 18 and 22. Mothers who have been pregnant before often feel it earlier (15 to 17 weeks).
Week 19: Vernix Caseosa
The fetus is around 15 cm. A protective waxy coating (vernix) covers the skin to protect it from amniotic fluid.
Week 20: Halfway Point — Anomaly Scan
The fetus is around 16 cm and weighs around 300 grams. The detailed anomaly scan (TIFFA scan) is done between weeks 18 and 22 to check fetal anatomy in detail — heart, brain, spine, kidneys, limbs. This is one of the most important scans in pregnancy care in HSR Layout and Attibele.
Week 21: Taste Buds Develop
The fetus is around 27 cm (head to heel). Taste buds develop and the fetus swallows amniotic fluid, getting accustomed to flavours from the mother's diet.
Week 22: Eyebrows and Eyelashes
The fetus is around 28 cm. Fine hair (lanugo) covers the body. Movements feel stronger.
Week 23: Hearing Develops
The fetus is around 29 cm. Hearing is developing — your baby can now hear muffled sounds from outside the womb. Some parents start playing music or talking to the bump.
Week 24: Lungs Begin to Mature
The fetus is around 30 cm and weighs around 600 grams. Lungs begin producing surfactant. The point of viability — survival outside the womb (with intensive care) is increasingly possible from this week.
Week 25: Reflexes Develop
The fetus is around 34 cm. Startle reflex develops. Eyes may begin to open.
Week 26: Eyes Open
The fetus is around 35 cm and weighs around 800 grams. Eyelids open and the fetus can blink. Brain activity surges.
Week 27: End of Second Trimester
The fetus is around 36 cm and weighs around 1 kg. Lung development continues. The glucose tolerance test (GTT) is usually done between weeks 24 and 28 to screen for gestational diabetes. Read more about high-risk pregnancy management if your GTT is abnormal.
Third Trimester (Weeks 28 to 40) — Final Preparation
The third trimester is when growth speeds up dramatically. Antenatal visits become more frequent — typically every 2 weeks from week 28 and every week from week 36. Pregnancy care in HSR Layout and pregnancy care in Attibele during this stage focuses on growth monitoring and birth planning.
Week 28: Brain Surface Develops
The fetus is around 37 cm and weighs around 1.1 kg. Brain develops its characteristic grooves and folds. Iron supplements are usually started.
Week 29: Bones Strengthen
The fetus is around 38 cm. Bones continue to harden. Mother's calcium needs increase.
Week 30: Increasing Movements
The fetus is around 40 cm and weighs around 1.4 kg. Movements should be felt regularly — start counting movements daily.
Week 31: Bone Marrow Production
The fetus is around 41 cm. Bone marrow takes over red blood cell production from the liver and spleen.
Week 32: Baby Settles Head-Down
The fetus is around 42 cm and weighs around 1.7 kg. Most babies start moving into a head-down position. Growth scan in HSR Layout is usually done around this time to assess fetal weight, position and amniotic fluid.
Week 33: Skull Stays Soft
The fetus is around 43 cm. Skull bones remain soft and unfused — to allow passage through the birth canal during delivery.
Week 34: Lungs Almost Mature
The fetus is around 45 cm and weighs around 2.1 kg. Lungs are nearly fully developed. Babies born now usually breathe independently.
Week 35: Increasing Weight Gain
The fetus is around 46 cm and weighs around 2.4 kg. Most weight gain in the final weeks is fat — preparing for life outside the womb.
Week 36: Term Approaches
The fetus is around 47 cm and weighs around 2.6 kg. Antenatal visits become weekly. Group B Streptococcus (GBS) test, hospital bag preparation, birth plan discussion, and choice of normal versus painless delivery are all reviewed. Read more about painless delivery in HSR Layout and Attibele.
Week 37: Early Term
The fetus is around 48 cm and weighs around 2.9 kg. Delivery any time from now is considered "early term" but generally safe.
Week 38: Full Term
The fetus is around 49 cm and weighs around 3.1 kg. Vernix and lanugo are mostly shed. Baby is fully ready.
Week 39: Active Term
The fetus is around 50 cm and weighs around 3.3 kg. The brain continues developing rapidly — this is why obstetricians prefer to wait for spontaneous labour rather than scheduling an early elective induction.
Week 40: Estimated Due Date
The fetus is around 51 cm and weighs around 3.5 kg. Only about 5 percent of babies are born exactly on the due date. Most arrive between week 38 and week 41.
Week 41 and 42: Post-Term
If labour does not begin by week 41, induction is usually planned. Beyond week 42, the placenta becomes less efficient and risks rise — Dr. Sanjana plans labour induction or caesarean delivery as appropriate.
Antenatal Checkup Schedule in Bangalore
A standard antenatal checkup schedule in HSR Layout or antenatal checkup schedule in Attibele with Dr. Sanjana L:
| Trimester | Visit Frequency | Key Investigations |
|---|---|---|
| Weeks 6 to 12 | Every 4 weeks | Dating scan, baseline blood and urine, NT scan + dual marker |
| Weeks 13 to 27 | Every 4 weeks | Anomaly scan (18 to 22 weeks), GTT (24 to 28 weeks) |
| Weeks 28 to 35 | Every 2 weeks | Growth scan, iron and calcium, Tdap vaccine |
| Weeks 36 to 40 | Every week | GBS test, position check, birth plan, induction planning if needed |
Key Pregnancy Tests Trimester by Trimester
First Trimester
- Beta-hCG, blood group and Rh, complete blood count
- TSH (thyroid), fasting and post-meal blood sugar, vitamin D
- Urine routine and culture
- Hepatitis B, HIV, VDRL screening
- Dating ultrasound (6 to 8 weeks)
- NT scan + dual marker (11 to 13 weeks 6 days)
Second Trimester
- Quad marker test (15 to 18 weeks, optional if dual marker not done)
- Anomaly / TIFFA scan (18 to 22 weeks)
- Glucose tolerance test (24 to 28 weeks)
- Repeat haemoglobin
Third Trimester
- Growth scan (28 to 32 weeks)
- Doppler ultrasound (36 weeks, if indicated)
- GBS test (35 to 37 weeks)
- Repeat haemoglobin and platelet count
- Pre-delivery anaesthesia review
Warning Signs by Trimester — When to Call Your Pregnancy Doctor
Most pregnancies progress smoothly. Call Dr. Sanjana immediately if you experience any of the following:
First Trimester Warning Signs
- Heavy bleeding (more than spotting)
- Severe one-sided pain with shoulder tip pain or fainting (possible ectopic)
- Persistent vomiting that prevents eating or drinking for 24 hours
- High-grade fever
Second Trimester Warning Signs
- Bleeding or fluid leak from the vagina
- Severe abdominal pain or contractions before 24 weeks
- Sudden severe headache, blurred vision, or upper abdominal pain (possible early preeclampsia)
- Reduced fetal movements after week 20
Third Trimester Warning Signs
- Reduced fetal movements (less than 10 movements in 2 hours)
- Sudden swelling of face, hands or feet, with headache or visual changes
- Heavy bleeding or watery fluid leak
- Severe abdominal pain or regular contractions before 37 weeks
- High blood pressure (above 140/90)
Lifestyle and Wellness Tips by Trimester
First Trimester Lifestyle
Start prenatal yoga in HSR Layout or Attibele under a qualified instructor. Eat small frequent meals to manage nausea. Sleep 8 to 9 hours. Avoid raw fish, soft cheeses, alcohol, smoking and second-hand smoke. Limit caffeine to 1 cup daily. Stay well hydrated.
Second Trimester Lifestyle
Continue prenatal yoga and brisk walking 30 minutes a day. Add iron-rich foods (greens, dates, jaggery) and calcium (milk, ragi, curd). Sleep on your left side from week 20 onwards to improve placental blood flow. Begin perineal massage from week 34 if planning vaginal delivery.
Third Trimester Lifestyle
Practise breathing exercises and pelvic floor exercises daily. Take frequent breaks at work, keep your feet elevated. Avoid long-distance travel after week 34. Pack your hospital bag by week 36. Discuss pain relief options — including painless delivery in HSR Layout and Attibele — with Dr. Sanjana well in advance.
Frequently Asked Questions
How is pregnancy dated week by week?
Pregnancy is dated from the first day of your last menstrual period (LMP). A dating ultrasound between 6 and 8 weeks confirms accuracy. If LMP is uncertain or cycles are irregular, the ultrasound dating overrides the LMP.
Which trimester is the most critical?
The first trimester (weeks 1 to 12) is most critical for fetal organ development and most miscarriages occur in this window. The third trimester is most critical for fetal growth, gestational diabetes, and preeclampsia monitoring.
How many ultrasound scans are needed during pregnancy?
A typical pregnancy in prenatal care in HSR Layout includes 4 to 5 routine scans: dating scan (6 to 8 weeks), NT scan (11 to 13 weeks), anomaly scan (18 to 22 weeks), growth scan (28 to 32 weeks), and a final scan around 36 weeks. Additional scans may be added for high-risk pregnancies.
When can I feel my baby move?
First-time mothers typically feel movements between weeks 18 and 22. Mothers who have been pregnant before may feel it as early as 15 to 16 weeks. After week 28, movements should be felt daily — count them every day.
Is normal delivery safe in Bangalore at HSR Layout or Attibele?
Yes. Both Health Nest (HSR Layout) and Raghava Multispeciality Hospital (Attibele) are equipped for normal delivery, painless delivery (epidural), and emergency caesarean delivery. Dr. Sanjana L has extensive experience supporting safe vaginal births. Read more about normal delivery in HSR Layout and Attibele and painless delivery options.
When should I switch to a high-risk pregnancy specialist?
You should consult Dr. Sanjana for high-risk pregnancy care in HSR Layout if you have gestational diabetes, hypertension, thyroid disease, age above 35, IVF/IUI conception, twins, or previous preterm delivery. Read more on high-risk pregnancy management.
What vaccines are needed during pregnancy?
Tdap vaccine between weeks 27 and 36 (to protect newborn from whooping cough), influenza vaccine in flu season, and COVID-19 booster as per current guidelines. Live vaccines (MMR, varicella) are avoided during pregnancy.
Can I exercise throughout pregnancy?
Yes — moderate exercise (walking, prenatal yoga, swimming, stationary cycling) is encouraged throughout pregnancy unless your doctor advises otherwise. Avoid contact sports, hot yoga, scuba diving, and any high fall-risk activity.
What should I eat during pregnancy?
A balanced Indian diet with adequate protein (dal, paneer, eggs, chicken, fish), iron-rich foods (greens, dates, jaggery), calcium (milk, ragi, curd), folate (leafy greens), and complex carbs (millets, brown rice). Read Dr. Sanjana's complete pregnancy diet plan with Indian foods.
How much weight should I gain during pregnancy?
Total recommended weight gain depends on pre-pregnancy BMI: 11 to 16 kg for normal BMI, 7 to 11 kg for overweight, 12 to 18 kg for underweight. Steady weight gain (1 to 2 kg in first trimester, then around 0.5 kg per week) is healthier than sudden gain.
When should I pack my hospital bag?
By week 34 to 36. Pack two bags — one for labour (light clothes, mobile charger, snacks, ID, all reports) and one for the postpartum stay (nursing bras, sanitary pads, baby clothes, blankets, baby toiletries).
What is painless delivery and is it safe?
Painless delivery (epidural analgesia) is a safe, well-established technique that uses a tiny catheter in the lower spine to deliver a continuous low-dose anaesthetic during labour. It does not slow labour or harm the baby when administered by a trained anaesthesiologist. Learn more about painless delivery in HSR Layout and Attibele.
Plan Your Pregnancy with Dr. Sanjana L
Every pregnancy is unique. A personalised pregnancy care plan in HSR Layout or pregnancy care plan in Attibele ensures every scan, blood test, vaccination and birth plan decision is tailored to your body, your baby, and your medical history.
Dr. Sanjana L (MBBS, MS OBG, Gold Medalist, FRM RGUHS, FMAS) consults at Health Nest (1162, 24th Main Road, Sector 2, HSR Layout — near Agara Lake) and Raghava Multispeciality Hospital (Attibele — opposite Syndicate Bank). She serves patients from Koramangala, BTM Layout, Sarjapura Road, Electronic City, Chandapura, Hosur Road, Bellandur, Bommanahalli, Singasandra, Kudlu Gate, Anekal, Jigani and across South Bangalore.
Call +91-9449031003 (HSR Layout) or +91-9980031006 (Attibele) to book your antenatal checkup. Or learn more about our complete pregnancy care programme, prenatal screening services, high-risk pregnancy support, normal delivery, painless delivery, caesarean delivery and postnatal care. Continue reading our early signs of pregnancy guide, first trimester pregnancy guide, pregnancy diet plan and normal delivery vs C-section guide for the journey ahead.
Dr. Sanjana L
MBBS MS ( OBG) Gold Medalist FRM ( RGUHS) FMAS
Gynaecologist & Obstetrician at Health Nest, HSR Layout & Raghava Hospital, Attibele, Bangalore
Dr. Sanjana L has over 10 years of experience in obstetrics and gynaecology. She is known for her compassionate, patient-centred approach and consults in English, Hindi, Kannada, and Telugu. She serves patients from HSR Layout, Attibele, Sarjapura, Electronic City, Koramangala, BTM Layout, Chandapura, and Hosur.