Week 12: End of the First Trimester
Week twelve marks the end of the first trimester. The risk of miscarriage drops significantly.
Baby size: Lemon (30-35 mm)
Baby development
New Reflexes and Amazing Skills
Your little one is becoming increasingly skillful. Their brain continues to develop, allowing them to acquire new reflexes. They can not only clench fists but also purse the lips and wrinkle the forehead.
What’s happening this week:
- Reflexes: The sucking reflex is developing — your baby may start sucking a finger right inside your belly!
- Digestive system: The intestine, which temporarily developed in the umbilical cord, now returns to the abdominal cavity.
- Vocal cords: The vocal cords begin to form — the basis of your child’s future voice.
- Organs: The pituitary starts producing its own hormones.
All these complex processes occur in a tiny body that weighs only about 14 grams.
Follow this amazing progress in our article "Fetal Development by Weeks".
Changes for mom
The Belly Grows, and Well‑Being Improves
Your uterus continues to grow, and now the doctor can feel its top (the fundus) above your pubic bone. The belly may become slightly noticeable.
What you may notice:
- Decreased frequency of urination: As the uterus rises higher, pressure on the bladder lessens.
- Dizziness: Due to circulatory changes and the effect of progesterone, you may feel mild dizziness, especially when standing up quickly.
- Heartburn: This symptom may still accompany you, as hormones relax the muscles of the digestive system.
- Energy surge: You may feel considerably more lively and active.
Your body is constantly changing. To understand what’s normal, read our article "Physical Changes of the Body During Pregnancy".
Overview
Week 12: End of the First Trimester!
Congratulations! Week twelve is the final chord of the first trimester. You have successfully navigated the most challenging and responsible stage of your baby's development. The risk of miscarriage drops significantly from now on.
Your fetus is now the size of a plum. It is fully formed, and its main job now is to grow, grow, and grow some more.
This is probably a long‑awaited week for you. Energy returns, nausea recedes, and you can truly enjoy how you feel. The uterus rises from the pelvic area into the abdomen, which can lessen pressure on the bladder.
This is a time to celebrate! You’ve done great. Ahead lies the “golden” second trimester, considered the most comfortable phase of pregnancy.
To recall the journey you’ve completed and sum up, check out our overview material "First Trimester: What You Need to Know".
Tips for mom
Time to Announce the News and Return to Activity
With the first trimester ending, many couples choose to share their joyful news with family and friends. It’s also a great time to bring sport back into your life.
Your next steps:
- Think about how to share the news. You can do it in person, by phone, or with a creative photo on social media. Choose the method that feels most comfortable to you.
- Talk to your doctor about physical activity. If there are no contraindications, swimming, prenatal yoga, or simply daily walks will benefit you.
- Focus on nutrition. Your appetite has likely improved. Emphasize protein, calcium, and iron.
- Start photographing the belly. If you haven’t begun yet, now is the time. Take a photo once a week from the same angle — it will be a wonderful memory.
Physical activity is not only beneficial but also enjoyable. Learn more about safe exercises in the article "Physical Activity and Exercises During Pregnancy".
Tips for partner
Celebrate and Plan Together
The end of the first trimester is your shared victory. Celebrate it and start looking toward the future together.
How to be an active participant:
- Celebrate the occasion. Arrange a romantic dinner or simply spend an evening together, discussing your feelings and dreams.
- Join in announcing the news. Be there when she shares the news with loved ones. It’s your shared moment.
- Become her “fitness partner”. Suggest walking together or swimming in a pool.
- Start discussing labor. It may seem far off, but now is a good time to start learning about types of delivery and partner‑assisted births.
Joint planning for the upcoming birth brings you closer. Start by creating a Birth Plan together.
Checklist
Your Action Plan for Week 12
The final touches of the first trimester.
- ✅ Celebrate the end of the first trimester!
- 📢 Announce the news to family and friends, if you’re ready.
- 🏃♀️ Discuss with your doctor and choose a safe form of physical activity for yourself.
- 📸 Take a weekly belly photo.
- 💰 Review the family budget taking into account upcoming baby purchases.
- 🧸 Start gathering ideas for the nursery or a list of essential items. The article about pre‑birth purchases will come in handy.