Pregnancy lasts approximately 40 weeks, divided into three trimesters. Each week brings new developments for both baby and mother. This guide covers your baby's growth, size comparisons, development milestones, and what you might be feeling at every stage of pregnancy — from Week 1 to Week 40.
Weeks 1-12
The foundation of your pregnancy. Your baby develops from a single cell to a fully formed fetus with all major organs beginning to form.
Weeks 13-27
Often called the "golden trimester." Energy returns, nausea fades, and you may begin to feel your baby move.
Weeks 28-40
The final stretch. Your baby gains weight rapidly and prepares for life outside the womb.
Week
4
Weight
Less than 1g
Length
0.04 inches
The embryo implants in the uterus. The neural tube, which becomes the brain and spinal cord, begins to form.
You may notice a missed period. Some women experience implantation bleeding and early pregnancy symptoms like fatigue.
Week
8
Weight
1 gram
Length
0.6 inches
All major organs have begun forming. Your baby has tiny fingers and toes. The heart is beating at about 150-170 beats per minute.
Morning sickness may peak. Fatigue is common. Your body is producing more blood to support the pregnancy.
Week
12
Weight
14 grams
Length
2.1 inches
First trimester complete. The risk of miscarriage drops significantly. Your baby can open and close their fingers and curl their toes.
Nausea often begins to ease. Energy may start returning. The uterus moves above the pelvic bone.
Week
16
Weight
100 grams
Length
4.6 inches
Your baby can make facial expressions. The skeleton is hardening from cartilage to bone. Hearing is developing.
The "pregnancy glow" may appear. You might feel baby's first movements (quickening) soon.
Week
20
Weight
300 grams
Length
10 inches
Halfway point! Your baby can hear your voice and heartbeat. The anatomy scan typically occurs now. Baby is swallowing amniotic fluid.
Most women are feeling baby movements regularly now. Energy levels are often good.
Week
24
Weight
600 grams
Length
12 inches
Viability week — your baby could survive outside the womb with intensive care. Fingerprints are fully formed. Lungs are developing.
Your belly is noticeably larger. You may experience backaches and sleep difficulties.
Week
28
Weight
1 kg (2.2 lbs)
Length
14 inches
Third trimester begins. Your baby can open and close their eyes. Brain development accelerates. Baby may respond to light.
Braxton Hicks contractions may begin. Shortness of breath is common as baby grows.
Week
32
Weight
1.7 kg (3.75 lbs)
Length
16.7 inches
Your baby is practicing breathing. Bones are hardening (except skull). Baby may be moving into head-down position.
Movement may feel different as space gets tight. Sleep may be challenging. Nesting instinct often kicks in.
Week
36
Weight
2.6 kg (5.7 lbs)
Length
18.7 inches
Baby is considered "early term." Lungs are nearly mature. Baby may "drop" into the pelvis.
Breathing may become easier if baby drops. Pelvic pressure increases. Final preparations for birth.
Week
40
Weight
3.4 kg (7.5 lbs)
Length
20 inches
Full term! Your baby is ready to meet you. All organ systems are mature and ready for life outside the womb.
Watch for signs of labor. Rest as much as possible. Your body knows what to do.
A full-term pregnancy lasts approximately 40 weeks, calculated from the first day of your last menstrual period. This is divided into three trimesters: First trimester (weeks 1-12), Second trimester (weeks 13-27), and Third trimester (weeks 28-40).
Most parents can find out their baby's gender during the anatomy scan ultrasound, typically performed between weeks 18-22. Some blood tests (NIPT) can determine gender as early as week 10.
Most first-time mothers feel their baby move (called “quickening”) between weeks 18-22. Experienced mothers may feel movement as early as week 16. By week 20, most mothers are feeling regular movements.
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