Week 11: Growing Strong - Bones, Muscles, and Movement

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Skeletal System Development

Week 11 brings significant changes to your baby's skeletal system. The process of ossification (bone formation) begins as cartilage structures start to harden into bone. This process will continue throughout pregnancy and even after birth, but the foundation is being laid now⁷.

The skull bones remain soft and separate to allow for brain growth and easier passage through the birth canal. The fontanelles (soft spots) won't close completely until your baby is 12-18 months old.

Muscle Development and Movement

Your baby's muscles are becoming stronger and more coordinated. While you can't feel them yet, your baby is making more frequent and varied movements. These include stretching, yawning, and even thumb sucking. These movements are crucial for proper muscle, bone, and joint development⁸.

The development of muscle tone and reflexes indicates that the nervous system is maturing. The connection between the brain and muscles is becoming more sophisticated, preparing for the coordinated movements needed after birth.

Rapid Growth Phase

Your baby now measures about 4.1 cm (1.6 inches) from crown to rump and weighs approximately 7 grams. This represents significant growth from just a few weeks ago. The head is still large relative to the body, but the proportions are gradually becoming more human-like.

The limbs are elongating and developing distinct segments. Fingers and toes are completely separated, and tiny fingernails and toenails are forming. Your baby can even make a fist and might be caught sucking their thumb on an ultrasound.

Digestive System Maturation

The digestive system continues to mature this week. The intestines, which have been developing within the umbilical cord, begin to move into the abdominal cavity. The stomach is producing digestive juices, and the liver is beginning to function more effectively.

Your baby regularly swallows amniotic fluid, which helps develop the digestive system and provides practice for feeding after birth. The kidneys are also becoming more efficient at filtering waste and producing urine.

Recipe: Bone-Building Calcium Bowl

Ingredients

• 1 cup Greek yogurt (plain)
• 1 tbsp chia seeds
• 1 tbsp almond butter
• 1/2 cup berries (blueberries or strawberries)
• 1 tbsp honey
• 2 tbsp granola
• 1 tbsp ground flaxseed

Instructions

1. Layer yogurt in a bowl
2. Mix in chia seeds and let sit for 5 minutes
3. Top with berries, granola, and flaxseed
4. Drizzle with honey and almond butter
5. Excellent source of calcium, protein, and omega-3s for bone development

Sources:

1. Holzer, L.A., et al. (2013). “Fetal bone development”
2. Reissland, N., et al. (2011). “Fetal movement patterns”