Second Trimester Ultrasound Pictures

Second Trimester: Week By Week

The second trimester starts from week 13 and ends at week 27 of your pregnancy. Below is the weekly calendar of events about your baby’s development during this time.

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• Your baby starts to produce urine and release it into the amniotic sac. This forms the amniotic fluid (1).

• Your baby’s bones start to harden in their skeleton, especially the long bones and that of the head.

• The skin still looks thin and transparent but will thicken soon.

Week 14

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• Your baby’s neck starts to appear more defined.

• The lower limbs become well developed.

• Red blood cells start forming in the baby’s spleen.

• The baby’s gender may start to become apparent this week.

• Your baby might be approximately 3.5 inches long and weigh about 45 grams.

Week 15

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• You may be able to see your baby’s bone development in the ultrasound images in the coming few weeks.
• The scalp hair pattern of the baby also starts forming.

Week 16

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Week 17

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• The toenails begin to appear.
• Your baby starts to become more active by rolling and flipping.
• Your baby’s heart starts to pump about 100 pints of blood every day.

Week 18

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• Ears begin to stand out from the sides of the head.
• Your baby may be able to start hearing.
• The digestive system has developed and started working.
• The eyes start to face forward.
• Your baby is 5.5 inches long and weighs about 200 grams.

Week 19

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• The pace of growth slows down a bit at this stage (3).
• Vernix caseosa begins to form which a cheeselike coating that covers the baby. It protects the baby’s skin against chafing, abrasions, and hardening due to exposure to amniotic fluid.
• The uterus and the genitals start to form for girls.

Week 20

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• You may start to feel your baby’s movements, also called quickening.
• Your baby has regular sleep and wake cycles.
• Your baby is approximately 6.5 inches long and weighs about 320 grams.

Week 21

• Your baby is now covered with lanugo which is fine downy hair.
• The sucking reflex of the baby starts to develop.

Week 22

• The hair and eyebrows of the baby start to become visible.
• Brown fat which maintains body heat also forms.
• For boys, testes begin to descend.
• Your baby will be about 7.5 inches long and weigh about 460 grams.

Week 23

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• The baby shows rapid eye movements (4).
• Ridges begin to form in the soles of the feet and palms of the hand which will later develop into footprints and fingerprints.
• Your baby starts to hiccup which will cause jerking movements.

Week 24

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• The baby’s skin appears pink to red because of the visible blood vessels. The skin also looks wrinkled and translucent.
• Your baby is approximately 8 inches long and weighs around 630 grams.

Week 25

• Baby starts to respond to familiar voice with movements (5).
• Spends most of his/her time sleeping in rapid eye movement (REM).

Week 26

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• Your baby’s lungs are developing. A substance called surfactant is produced by the lungs that allow the air sacs to inflate and keeps them from collapsing while they deflate.
• Your baby is around 9 inches from crown to rump and weighs about 820 grams.

Week 27

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• It marks the end of the trimester.
• The nervous system continues to develop and mature.
• Your baby’s skin starts to look smoother because of fat production.

Your baby has grown and developed a great deal from the beginning of week 13 until now. You are now one step closer to holding the little munchkin in your arms as you have only one more trimester to go. Be sure to make the most of each day as this is the time you will cherish forever. So, drink plenty of water, eat healthy food, and follow up with your doctor’s appointment to deliver a healthy and happy baby.