Week 20 Fetal Development: Anatomy Scan and Halfway Milestone
Welcome to the halfway point of your pregnancy! At 20 weeks, your baby is about the size of a banana and this week typically brings the exciting anatomy ultrasound. You may start feeling fetal movement, and your baby's development has reached impressive milestones with all major organs functioning.
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Your Baby's Development at 20 Weeks
At the halfway point of pregnancy, your baby has achieved remarkable development milestones. All major organ systems are not only formed but functioning at increasingly sophisticated levels. Your baby now looks unmistakably human and is becoming more active and responsive to external stimuli.
Major Achievements This Week
- Sensory Development: All five senses are developing and functional
- Brain Growth: Rapid brain development with billions of neurons forming
- Movement Coordination: More coordinated and purposeful movements
- Digestive Function: Swallowing amniotic fluid and producing meconium
- Immune Development: Immune system beginning to function
- Sex Determination: External genitalia clearly visible on ultrasound
Sensory System Development
Hearing
Can hear sounds from outside the womb, including your voice, heartbeat, and music
Taste
Taste buds are fully formed and can distinguish different flavors in amniotic fluid
Touch
Responds to touch, may grab umbilical cord or touch face with hands
Sight
Eyelids are still fused but retina is developing light sensitivity
Smell
Olfactory system is developing, though not fully functional until after birth
The Anatomy Ultrasound (18-22 weeks)
The anatomy scan, also called the mid-pregnancy ultrasound or level 2 ultrasound, is typically performed between 18-22 weeks, with 20 weeks being the most common timing. This detailed examination provides crucial information about your baby's development and health.
What the Anatomy Scan Reveals
Growth and Size
- Biparietal diameter (head width)
- Head circumference
- Abdominal circumference
- Femur length (thigh bone)
- Estimated fetal weight
Organ Assessment
- Heart structure and function
- Brain development and ventricles
- Spine alignment and development
- Kidney function and bladder
- Stomach and digestive system
Physical Features
- Facial profile and features
- All four limbs and digits
- Sex determination (if desired)
- Overall body proportions
- Movement and positioning
Pregnancy Assessment
- Placental position and function
- Amniotic fluid levels
- Umbilical cord structure
- Cervical length
- Uterine structure
Preparing for Your Anatomy Scan
- Timing: Schedule between 18-22 weeks for optimal visualization
- Duration: Allow 30-60 minutes for the examination
- Preparation: No special preparation usually required
- Support Person: Most facilities allow partners to attend
- Questions: Prepare any questions you want to ask
- Sex Reveal: Decide beforehand if you want to know the sex
Fetal Movement at 20 Weeks
For many women, 20 weeks marks the beginning of consistently feeling fetal movement. These first noticeable movements, called "quickening," are an exciting milestone in your pregnancy journey.
What Fetal Movement Feels Like
Early fetal movements are often described as:
- Fluttering: Light, butterfly-like sensations
- Bubbling: Similar to gas bubbles or stomach rumbling
- Gentle Taps: Light poking or patting sensations
- Rolling: Smooth, wave-like movements
- Quickening: Sudden, brief movements
Movement Patterns at 20 Weeks
- Frequency: May feel movements several times per day
- Timing: Often more noticeable when you're resting
- Response to Stimuli: May increase with sounds, touch, or after meals
- Position Dependent: More noticeable in certain positions
- Variability: Some days more active than others
Factors Affecting Movement Detection
Maternal Factors
- Previous pregnancies (experienced mothers feel movement earlier)
- Body weight and abdominal wall thickness
- Activity level and position
- Attention and focus on sensations
Pregnancy Factors
- Placental position (anterior placenta may muffle movements)
- Amniotic fluid levels
- Baby's position and size
- Baby's sleep-wake cycles
For more detailed information about fetal movement patterns and monitoring, visit our comprehensive fetal movement guide.
Size and Physical Development
Your baby has grown tremendously and now measures about the size of a banana. The proportions are becoming more baby-like, and detailed features are clearly visible on ultrasound.
Size Measurements at 20 Weeks
Crown-to-Rump Length
166mm (approximately 6.5 inches)
Weight
300 grams (approximately 10.6 ounces)
Visual Comparisons
Banana, large carrot, or small cantaloupe
Detailed Physical Development
Facial Development
- Eyes are well-formed but still closed
- Eyebrows and eyelashes are growing
- Nose and lips are fully formed
- Ears are in final position and fully functional
- Facial expressions are developing
Body Proportions
- Head is still large but more proportionate
- Arms and legs are properly proportioned
- Torso is lengthening and filling out
- Neck is well-defined
- Overall appearance is increasingly human-like
Skin and Hair
- Skin is becoming less transparent
- Vernix caseosa (protective coating) is forming
- Lanugo (fine hair) covers the body
- Hair on the head may be visible
- Fingerprints and footprints are forming
Limb Development
- Arms and legs move actively
- Fingers and toes are fully developed
- Nails continue to grow
- Joints are flexible and functional
- Muscle development is advancing
Your Body at 20 Weeks Pregnant
At 20 weeks, you're likely experiencing the most comfortable phase of pregnancy. Your energy has likely returned, morning sickness has usually subsided, and you're beginning to show a noticeable baby bump.
Physical Changes
- Baby Bump: Clearly visible and growing upward from pelvis
- Uterus Size: About the size of a cantaloupe, reaching navel level
- Weight Gain: Typical gain is 8-10 pounds by this point
- Breast Changes: Continued growth and darkening of areolas
- Skin Changes: Possible pregnancy glow, linea nigra may appear
Internal Changes
- Blood Volume: Increased by about 25-30%
- Heart Rate: Elevated by 10-15 beats per minute
- Blood Pressure: Often at lowest point of pregnancy
- Lung Capacity: Beginning to be affected by uterine growth
- Digestive System: Continued slowing due to progesterone
Postural Changes
- Center of Gravity: Beginning to shift forward
- Back Curvature: May increase to accommodate growing belly
- Joint Loosening: Relaxin hormone affecting ligaments
- Gait Changes: May begin to waddle slightly
- Balance: May notice slight changes in balance
Common Symptoms at 20 Weeks
The second trimester is often called the "honeymoon period" of pregnancy because many uncomfortable early symptoms have resolved. However, some new symptoms may appear as your body continues to change.
Positive Changes
- Increased Energy: Most women feel more energetic
- Reduced Nausea: Morning sickness typically resolved
- Better Mood: Hormones stabilizing, mood improving
- Improved Appetite: Interest in food returns
- Better Sleep: Less interrupted sleep than first trimester
- Pregnancy Glow: Increased circulation creating healthy appearance
New or Continuing Symptoms
- Round Ligament Pain: Sharp pains on sides as uterus stretches
- Braxton Hicks Contractions: Mild, irregular uterine tightening
- Backache: Lower back pain from postural changes
- Heartburn: May develop as uterus presses on stomach
- Constipation: Continued slow digestion
- Nasal Congestion: Pregnancy rhinitis may persist
- Increased Appetite: Growing baby's nutritional needs
Skin and Appearance Changes
- Linea Nigra: Dark line down center of abdomen
- Melasma: Dark patches on face (pregnancy mask)
- Stretch Marks: May begin appearing on belly, breasts, hips
- Spider Veins: Small red veins may appear
- Skin Tags: Small skin growths in friction areas
- Dry Skin: Stretching skin may become itchy
Medical Disclaimer: This information is for educational purposes only and should not replace professional medical advice. Every pregnancy is unique, and development can vary between individuals. Always consult with your healthcare provider about your specific pregnancy, any concerns you may have, and appropriate prenatal testing options.