Baby is the size of a bell pepper
👶 Baby's development
The baby hears well and reacts to sounds. The brain actively builds neural connections.
💛 How mom feels
Most moms feel movement by now. Lower back pain may appear. Sleep on your left side.
📖 Tip of the week
The anatomy scan — the most important ultrasound of all. The doctor carefully examines every organ, takes measurements, and checks the placenta. You may find out the sex — if the baby cooperates!
🔬 Detailed baby development
- The fetus's ears are now in their final position and it can begin hearing sounds from outside the womb
- Myelin (a protective coating) starts forming around the nerves, essential for signal transmission
- If female, the uterus and fallopian tubes are formed; if male, the genitals may be visible on ultrasound
- The fetus yawns, stretches, and makes facial expressions frequently
- Vernix caseosa (a waxy, protective coating) begins to form on the skin
- The fetus is about 14.2 cm long and weighs approximately 190 grams, roughly the size of a bell pepper
🤱 What mom may feel
- Fetal movements (kicks, punches, rolls) become more distinct and recognizable
- Leg cramps, especially at night, become more common
- Lower back pain may increase as the belly grows and posture changes
- Dizziness or lightheadedness from blood pressure changes and the growing uterus pressing on blood vessels
- Increased appetite and food cravings continue
🏥 Tests and check-ups
The mid-pregnancy anatomy scan (also called the morphology or anomaly ultrasound) is typically scheduled between weeks 18-22. This detailed ultrasound examines all fetal organs, measures growth, checks the placenta position, amniotic fluid volume, and can reveal the baby's sex. This is one of the most important prenatal ultrasounds.
💡 Tips for this week
- Stretch your calf muscles before bed and stay hydrated to help prevent nighttime leg cramps
- Eat magnesium-rich foods (bananas, nuts, dark chocolate, leafy greens) as magnesium deficiency can contribute to cramps
- Start talking, singing, or playing music to your baby — hearing is developing
- Consider a prenatal support belt if back pain becomes bothersome
❓ Frequently asked questions
What does the anatomy scan check for?
The anatomy scan systematically examines the brain, spine, face, heart, stomach, kidneys, bladder, limbs, and other organs for structural abnormalities. It also measures the baby, checks placenta position, and evaluates amniotic fluid levels. It typically takes 30-45 minutes.
Can the baby hear me talking?
Yes, from around 18 weeks the inner ear is developed enough to detect sound. The baby can hear your heartbeat, blood flow, digestion, and increasingly, external voices and music. Studies show babies recognize their mother's voice at birth.
Are leg cramps a sign of something wrong?
Leg cramps are usually a normal, if unpleasant, part of pregnancy caused by pressure on nerves, fatigue, and possibly mineral deficiencies. However, persistent swelling or pain in one leg should be reported as it could indicate a blood clot.
Will I find out the sex at the anatomy scan?
Most ultrasound technicians can determine the sex at the anatomy scan if the baby is in a cooperative position. Let your provider know beforehand if you do or do not want to know. Accuracy at this stage is typically over 99%.
📝 Week 18 of pregnancy: what's happening
At week 18, your baby is approximately 14.2 cm long and weighs around 190 g — about the size of a sweet potato. The nervous system is maturing rapidly, with nerves being covered in a protective layer called myelin which speeds up nerve signal transmission — this process continues well into childhood. Your baby’s genitalia are now fully formed and may be visible on ultrasound. The digestive system is practising its function as the baby swallows amniotic fluid, which is processed by the gut.
By now, most women are clearly showing a bump and fetal movements may be felt more regularly, though patterns are not yet consistent. You might notice Braxton Hicks contractions beginning — these are painless, irregular tightenings of the uterus that serve as practice for labour and are entirely normal. Skin changes are common at this stage; the pregnancy glow reported by many women is due to increased blood volume and oil production, though others may experience acne or skin dryness instead. Your hair may feel thicker and more lustrous due to hormonal effects slowing normal hair shedding.
The anomaly scan (20-week scan) is typically offered between weeks 18 and 21 — you should receive your appointment letter soon if you haven’t already. This detailed ultrasound examines your baby’s structure and checks the position of the placenta. It looks at the brain, spine, heart, kidneys, and limbs to identify any structural differences. Preparing a list of questions in advance is a good idea, and you may wish to bring a support person to the appointment.
Ensure your diet is rich in calcium (found in dairy products, fortified plant milks, broccoli, and almonds) to support your baby’s rapidly developing skeleton. If you are experiencing heartburn, try eating smaller, more frequent meals, avoiding lying down immediately after eating, and propping up the head of your bed slightly. Sleeping on your left side from this stage onwards is recommended as it improves circulation to the placenta and kidneys — a pregnancy pillow can make this much more comfortable. Begin researching infant feeding options so you feel well informed before your baby arrives.
⚠️ When to see a doctor
- Vaginal bleeding of any amount
- Severe headache or vision changes
- Severe abdominal or lower back pain
- Swelling of face and hands (possible preeclampsia)
- Decreased or absent fetal movement after 20 weeks
- Blood pressure above 140/90
Sources
- WHO recommendations on antenatal care (2016)
- ACOG Practice Bulletins
- Williams Obstetrics, 26th Edition
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