How your baby grows and changes in the second trimester


By the time your second trimester begins, your baby has already progressed remarkably. What started as a mere clump of cells has grown into a tiny being who can now stretch, hiccup, and even sigh in your womb. Over the course of your second trimester, your baby’s growth will only gain speed as he or she races toward delivery day. Let’s take a look at some of the changes your little one’s making during these three months:

Measurements: At the start of your second trimester, your baby will weigh about 1 ounce and measure 3-4 inches in length from crown to rump. By the end of this trimester, your little one will weigh 2.5-3 pounds and measure almost 10 inches in length.

Breathing: While your baby doesn’t breathe in utero, he or she will begin practicing the movements around week 14 to prepare for life in the real world. By week 17, he or she is breathing out amniotic fluid and you may notice his or her tiny chest rising and falling on an ultrasound. By week 26, your baby can inhale and exhale.

Movements: Your little one will begin bending and flexing fingers, hands, feet, and toes. While you may not notice it yet, your baby is pretty active in there – flipping, kicking, and rolling around. If you’re a first time mom, you may not pick up on these movements until week 20 or later.

Protective layer: Your new son or daughter is developing a layer of very fine hair that covers his or her entire body. Once born, your baby may appear to be covered in tiny soft feathers. This is called lanugo. It helps keep your little one warm and to regulate body temperature. Your baby will naturally lose this in the weeks after birth.

Hearing: Your baby’s hearing develops by week 17. Between weeks 17-20, he or she can hear your voice and heartbeat–and may even startle at loud noises outside of your body. Later on, around week 23, your baby will improve at telling the difference between noises happening inside and outside of your body.

Reproductive organs: If you’re growing a little girl, her ovaries will produce more than 2 million eggs in the second trimester. This number will decrease drastically before birth. If your baby is a boy, his prostate gland starts forming at week 18.

Touch and taste: Around week 18, your little one begins to develop his or her unique fingerprints. Just a few weeks later, your baby’s tongue begins to develop tastebuds. Between weeks 20-22, your baby’s brain advances to allow your little one to experience touch. Take a look during the anatomy scan and you may see your baby rubbing his or her cheek or even sucking a thumb. Your little one may even respond to your touch now. Try giving your belly a gentle poke while you talk to your baby. You’ll be surprised to find your little one just might respond with a kick!

Survival: By week 24, your baby has a 25 percent chance of surviving outside the womb, thanks to the production of white blood cells and the partial development of baby’s lungs.

Teeth: Around week 25, your little one’s permanent teeth begin to form within the gums–though you won’t see them until your child turns 6 or 7 years old and loses his or her baby teeth.

Spine: Your baby’s spine starts to take shape slowly over the course of the second trimester to support your little one’s body as he or she continues to grow.

Facial features: At week 25, your baby’s nostrils take shape and open. A few weeks later and he or she can open his or eyelids and may even respond to a bright light shone outside your body. During this time, your little one is accumulating fat beneath his or her skin, resulting in a chubbier and rounder appearance.

Read more: The first trimester: How your baby takes shape

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