Week 23: Development of the Immune System
The twenty-third week is a time of active development of your baby's immune system.
Baby size: Grapefruit (85-90 mm)
Baby development
Dances in the Belly and Lung Development
Your baby is getting stronger, and his movements are no longer gentle nudges but real "dances". You can clearly feel when he flips or wiggles.
What’s happening this week:
- Lungs: Production of surfactant is a key event. Blood vessels in the lungs are also actively developing.
- Movements: They become more intense, and you can feel them regularly.
- Skin: It is still reddish and wrinkled, as subcutaneous fat is just beginning to accumulate.
- Eyes: Rapid eye movement (REM sleep phase) begins, indicating the development of dreaming!
Your fetus now weighs over 500 grams, and its length is almost 30 centimeters.
Changes for mom
New Lines on the Body and Comfort Tips
Your belly continues to grow confidently, which can lead to some discomfort and visible skin changes.
What you may notice:
- Dark line on the abdomen (Linea Nigra): It may become even more noticeable. This is a normal phenomenon that will disappear after delivery.
- Low back and pelvic pain: Increased weight and joint relaxation can cause discomfort.
- Swelling: Mild swelling of the legs and arms may persist.
- Forgetfulness: The "pregnant brain" can still make its presence known.
These and other changes are a normal part of pregnancy. To learn more, read our article "Physical Changes of the Body During Pregnancy".
Overview
Week 23: Baby Prepares for the First Breath
At the twenty-third week your baby reaches an important milestone — his lungs begin producing surfactant. This special substance will help the alveoli stay open after birth and make the first independent breath.
He is now the size of a large eggplant or a grapefruit. His hearing becomes even sharper, and he can not only hear your voice but also distinguish it among other sounds. Your daily conversations are the best way to connect with him.
For you this week is a time of active belly growth and possibly new sensations. You may feel a bit clumsy due to a shift in your center of gravity, so it’s important to move carefully.
Preparing for breathing is one of the most important steps on the road to independent life. Every day your baby diligently trains to be ready to meet you.
You continue to enjoy the benefits of the second trimester. To learn more about this period, check out our detailed guide "Second Trimester: What You Need to Know".
Tips for mom
Self‑Care and Preparing for the Future
Now it’s important to focus on your comfort and continue planning the next steps.
What to do:
- Wear a maternity support belt. If you feel back pain, a special supportive belt can greatly relieve it.
- Do stretching exercises. Light stretching helps reduce muscle and joint soreness.
- Drink plenty of water. This helps reduce swelling and is important for overall well‑being.
- Start looking for a pediatrician. This is a great time to gather recommendations and choose a doctor for your baby.
Physical activity can significantly improve your well‑being. Read about safe exercises in the article "Physical Activity and Exercises".
Tips for partner
Future Dad: Support and Involvement
Your participation in preparing for the baby’s arrival makes this journey easier and more joyful for both.
Your contribution to the shared effort:
- Help her stay comfortable. Offer a back massage, assist with putting on shoes, and support her during walks.
- Search for a pediatrician together. Your opinion matters. Read reviews together and compile a list of candidates.
- Talk to the baby. Tell her stories or simply talk about your day. She can hear you.
- Be patient and attentive. Your emotional support is what she needs most.
Finding “the right” doctor for the child is a responsible step. Helpful tips can be found in the article "How to Find Your Pediatrician: Selection Criteria".
Checklist
Your Action Plan for Week 23
We continue moving confidently and calmly.
- ✅ Start looking for a pediatrician for the upcoming baby.
- 🤰 Consider purchasing a maternity support belt.
- 💧 Monitor your water balance to reduce swelling.
- 🎵 Play music for the baby regularly or sing to her.
- 📝 Begin compiling a list of items for the maternity hospital.
- 📚 Get inspired for preparation by reading the article "Packing the Hospital Bag".