Pregnancy Week by Week: Your Complete Guide From Bump to Baby

Pregnancy is a journey like no other. In just 40 weeks, a single fertilized egg transforms into a fully formed human being — and your body goes through incredible changes to make it happen.

Whether you just saw those two pink lines or you are well into your third trimester, understanding what happens at each stage can help you feel more in control and less anxious. This guide walks you through every major milestone, from conception to delivery day.

Not sure how many weeks you are? Use our free due date calculator or how far along am I tool to find out.

First Trimester (Weeks 1-13): The Foundation

The first trimester is all about building the foundation. Your baby goes from a cluster of cells to a tiny fetus with all major organs formed. For you, it often means morning sickness, fatigue, and a lot of adjusting.

Weeks 1-4: Conception

Surprisingly, you are not actually pregnant during weeks 1 and 2. Pregnancy is dated from the first day of your last period, so conception typically happens around week 2-3. Once the egg is fertilized, it travels down the fallopian tube and implants in the uterus.

What is happening:

• Ovulation occurs around day 14 of your cycle
• Sperm fertilizes the egg within 24 hours of ovulation
• The fertilized egg (zygote) divides into a blastocyst
• Implantation occurs 6-12 days after conception
• The placenta begins to form

Symptoms you may notice: Light spotting (implantation bleeding), mild cramping, breast tenderness. Most women do not realize they are pregnant yet.

Tip: Start taking a prenatal vitamin with at least 400mcg of folic acid if you are trying to conceive. Use our ovulation calculator to identify your fertile window.

Weeks 5-8: The Heart Begins to Beat

This is when most women discover they are pregnant. A home pregnancy test can detect hCG (the pregnancy hormone) by week 4-5.

Baby's development:

• The neural tube (which becomes the brain and spinal cord) is forming
• The heart begins to beat around week 6 — it is about the size of a poppy seed
• Arm and leg buds appear
• The embryo is about the size of a blueberry by week 8

Common symptoms: Morning sickness (nausea at any time of day), fatigue, frequent urination, food aversions, heightened sense of smell, mood swings.

Key appointments: Schedule your first prenatal visit. Your doctor will confirm the pregnancy, check your blood type, and run initial blood work.

Weeks 9-13: The End of the First Trimester

Baby's development:

• All major organs have begun to form
• Fingers, toes, and fingernails are developing
• The baby starts to move (though you cannot feel it yet)
• By week 12, the baby is about the size of a passion fruit
• The genital tubercle begins to differentiate — this is when nub theory can start to apply

Common symptoms: Morning sickness may begin to ease. You might notice a small baby bump starting. Increased appetite is common as nausea fades.

Key appointments: First trimester screening (optional), which includes a blood test and nuchal translucency ultrasound around weeks 11-13. This is also the window for NIPT blood testing, which can tell you your baby's gender with 95-99% accuracy.

Exciting milestone: If you have a scan at 12 weeks, this is when you can try nub theory for an early gender prediction! Our professional analysis service can analyze your ultrasound using multiple methods.

Second Trimester (Weeks 14-27): The Golden Period

Most women consider the second trimester the best part of pregnancy. Morning sickness typically fades, energy returns, and you start to feel your baby move. It is also when your belly really starts to show.

Weeks 14-17: Energy Returns

Baby's development:

• The baby is growing rapidly — from 3 inches to about 5 inches
• Hair begins to grow on the head
• Bones are hardening from cartilage
• The baby can make facial expressions
• Eyes are sensitive to light

Common symptoms: Growing appetite, round ligament pain (sharp pains on the sides of your belly), skin changes (the "pregnancy glow" or acne), nasal congestion.

Weeks 18-22: Feeling Movement

This is the moment many parents have been waiting for — the anatomy scan at 18-22 weeks.

Baby's development:

• You will likely feel the first flutters of movement (called "quickening") around weeks 18-22 for first pregnancies, or 16-20 for subsequent ones
• The baby is about 10 inches long by week 20 — halfway there!
• A protective coating called vernix covers the baby's skin
• The baby can hear sounds from outside the womb

Key appointments: The anatomy scan ultrasound at 18-22 weeks is the most detailed scan of your pregnancy. The sonographer checks all major organs, the placenta, and amniotic fluid levels. This is also when gender can be confirmed with high accuracy through direct visualization.

Exciting milestone: This is the most reliable time to find out your baby's gender through ultrasound. If you want an earlier prediction, our gender prediction service uses methods like Ramzi theory, nub theory, and skull theory to give you results weeks before your anatomy scan.

Weeks 23-27: Viability and Preparation

Baby's development:

• The baby weighs about 1.5-2 pounds by week 27
• Lungs are developing but not yet mature
• The baby has a regular sleep-wake cycle
• Eyes open for the first time around week 26-27
• Fingerprints have formed

Common symptoms: Braxton Hicks contractions (practice contractions), swelling in feet and ankles, back pain, heartburn, trouble sleeping.

Tip: If you have not started your hospital bag checklist, now is a good time to begin gathering items.

Third Trimester (Weeks 28-40): The Home Stretch

The final stretch is both exciting and uncomfortable. Your baby is putting on weight, and your body is preparing for delivery.

Weeks 28-32: Rapid Growth

Baby's development:

• The baby's brain develops rapidly, forming billions of neurons
• Fat accumulates under the skin, giving the baby a rounder appearance
• The baby can blink, dream (REM sleep), and practice breathing movements
• By week 32, the baby is about 16-17 inches long and weighs 3.5-4 pounds

Common symptoms: Shortness of breath (your uterus is pushing against your diaphragm), frequent urination returns, Braxton Hicks contractions increase, stretch marks may appear.

Key appointments: Third trimester screening, glucose tolerance test (if not done already), and regular checkups every 2 weeks.

Weeks 33-36: Getting Into Position

Baby's development:

• The baby typically moves into a head-down position in preparation for birth
• Lungs are nearly mature
• The baby practices sucking and grasping
• By week 36, the baby is considered "early term" if born

Common symptoms: Pelvic pressure, difficulty sleeping, increased vaginal discharge, nesting instinct kicks in.

Tip: Pack your hospital bag by week 35-36. Install the car seat. Review your birth plan with your provider.

Weeks 37-40: Ready to Meet Your Baby

Baby's development:

• The baby is full-term at 39 weeks
• Average birth weight is 7-7.5 pounds
• The baby continues to gain about half a pound per week
• Most of the lanugo (fine body hair) has shed

Common symptoms: Strong Braxton Hicks, cervical dilation and effacement begins, "lightning crotch" (sharp pains as the baby presses on nerves), loss of the mucus plug, nesting reaches peak intensity.

Signs of labor: Regular contractions that get stronger and closer together, water breaking, lower back pain that comes and goes in waves.

Key Appointments Timeline

Week	Appointment	Purpose
6-10	First prenatal visit	Confirm pregnancy, blood work, due date
11-13	First trimester screening	Nuchal translucency, optional NIPT
11-13	Dating scan	Confirm gestational age
18-22	Anatomy scan	Detailed organ check, gender confirmation
24-28	Glucose screening	Check for gestational diabetes
28	Rh antibody test	For Rh-negative mothers
32-36	Growth scan (if needed)	Check baby's growth and position
36	Group B Strep test	Vaginal/rectal swab
37-40	Weekly checkups	Cervical checks, fetal monitoring

Pregnancy Symptoms by Trimester

Symptom	First Trimester	Second Trimester	Third Trimester
Morning sickness	Yes (peaks week 9)	Fading	Usually gone
Fatigue	Yes	Improves	Returns
Breast tenderness	Yes	Improves	May return
Frequent urination	Yes	Better	Yes (worse)
Heartburn	Sometimes	Yes	Yes
Back pain	No	Sometimes	Yes
Swelling	No	Mild	Yes
Braxton Hicks	No	Sometimes	Yes
Shortness of breath	No	Sometimes	Yes

Early Gender Prediction During Your Pregnancy

If you want to know your baby's gender before your 18-20 week anatomy scan, here is a timeline of when different methods become available:

Week	Method	Accuracy	Type
6+	Ramzi Theory	Varies	Ultrasound analysis
10+	NIPT Blood Test	95-99%	Medical (blood draw)
11-14	Nub Theory	80-95%	Ultrasound analysis
Any	Skull Theory	Varies	Ultrasound analysis
18-20	Anatomy Scan	95-99%	Medical (ultrasound)

Our Full Comprehensive package applies all three prediction theories to your ultrasound for the strongest possible early prediction. Not sure which week you are in? Use our how far along calculator to find out.

Tips for a Healthy Pregnancy

Nutrition

• Take a daily prenatal vitamin with folic acid, iron, and DHA
• Eat a balanced diet rich in fruits, vegetables, lean protein, and whole grains
• Stay hydrated — aim for 8-10 glasses of water per day
• Avoid raw fish, unpasteurized cheese, deli meats, and excessive caffeine
• Read our complete guide on foods to eat during pregnancy

Exercise

• Aim for 30 minutes of moderate exercise most days (walking, swimming, prenatal yoga)
• Avoid contact sports, hot yoga, and activities with fall risk
• Kegel exercises help prepare for delivery
• See our guide on safe exercises during pregnancy

Sleep

• Sleep on your side (left side is recommended) after the first trimester
• Use a pregnancy pillow for support
• Aim for 7-9 hours per night
• Check our pregnancy sleep tips for more advice

Mental Health

• Hormonal changes can cause mood swings — this is normal
• Talk to your partner, friends, or a therapist if you feel overwhelmed
• Prenatal depression affects 1 in 7 women — seek help if needed
• Join a pregnancy support group (online or in person)

Preparing for Baby's Arrival

By your third trimester, you should have:

1. Packed your hospital bag
2. Installed the car seat
3. Set up the nursery (or at least a bassinet)
4. Chosen a pediatrician
5. Discussed your birth plan with your provider
6. Prepared meals for the freezer
7. Arranged help for the first few weeks postpartum

Fun Ways to Pass the Time

Waiting for your baby can feel endless. Here are some fun things to try:

• Take our Old Wives' Tales gender quiz for 15 fun predictions
• Try the Chinese gender predictor based on your age and conception month
• Start a baby name shortlist with our 2026 baby names guide
• Browse gender reveal ideas for when you find out
• Get an early gender prediction with our professional analysis service

Disclaimer

This article is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider for personalized guidance about your pregnancy. Every pregnancy is different, and the timelines described above are general guidelines, not strict rules.

Want to know your baby's gender early? Upload your ultrasound → and get a professional prediction report starting at $9.99.