By: Vaishnavi Raju | Date: February 17, 2021

Second Trimester of Pregnancy- How The Fetus Develops Week By Week?

"The lungs, heart, and blood system of the baby develops in the second trimester of pregnancy".

The second trimester of pregnancy stretches from the 13th week to the 27th week of gestation. During the second trimester of pregnancy, the fetal development happening week by week is very rapid. You may start to feel the baby’s movement as your bumps grow in size. The second trimester of pregnancy is a crucial phase where fetal development has many stages. In the second trimester morning, sickness and tiredness ease. The fetus develops functioning organs, nerves, and muscles.

What is the second trimester of pregnancy?

The middle part of your pregnancy is called the second trimester. This phase is very crucial in the aspect of fetal development stages. During these times fetal development week by week becomes very rapid and changes occur almost daily. At the beginning of the second trimester, the baby is 3 inches in size. During the second trimester of pregnancy, the baby grows up to 9 inches. You will start feeling the movement of the baby in the second trimester of pregnancy. During the starting of the second trimester, the baby’s head is the biggest part of the body. In this phase, fetal development progresses rapidly month by month.

What happens in 4th month of pregnancy?

In the 4th month of pregnancy fetal development is rapid. In the 4th month, the nervous system of the baby starts functioning. Fetal development in the 16th week is fast and you can now feel the baby’s movements.

Fetal development week by week

Week 13

The baby starts making Urine and releases in amniotic fluid. Skull and long bones are formed.

Week 14

The baby’s neck becomes more defined. Red blood cells start forming in the baby’s spleen.

Week 15

The baby grows rapidly in the 15th week of pregnancy. The bone development continues and the baby’s scalp hair becomes visible.

Week 16

In the 16th week of fetal development, the baby’s skin gets thicker and the head is erect. You can feel the baby’s movements.

Week 17

At 17th-week toenails begin to develop. Your baby’s heartbeat becomes more audible.

How does a fetus grow in the 5th month of pregnancy?

By the end of 5th month, the baby starts to move rapidly. At this phase, your baby is about 10 inches long.

Fetal development chart

Week 18

The baby starts hearing sounds in the 18th week. Your baby’s digestive system has started working. Fetal development during this phase of pregnancy is about 5.5 inches.

Week 19

In the 19th week during the second trimester of pregnancy, the growth slows. A greasy coating called vernix caseosa covers the baby. It protects the baby’s skin from amniotic fluid.

Week 20

Second-trimester pregnancy symptoms change week by week. In the 20th week, you may feel the quick movements of the baby. Your baby is regularly sleeping and waking.

Week 21

The baby begins to suck its thumb. The fetus is covered with fine hair.

Week 22

The baby’s eyebrows and hair are visible in the 22nd week. Brown fat is forming now.

What changes occur in the 6th month of pregnancy?

Fetal development calculator can tell you that by the end of the 6th month your baby is 12 inches long. The baby’s skin is reddish and veins are visible.

Fetal development timeline week by week

Week 23

In this phase of the second trimester of pregnancy, the baby begins to have rapid eye-movements. Fingerprints and footprints begin to develop and the babies begin hiccupping.

Week 24

The baby’s skin is wrinkled, translucent, and pink. The baby now weighs 630 grams.

Week 25

Your baby might be able to respond to the sounds. Your baby spends most sleep time in REM (Rapid- eye movement)

Week 26

The baby’s lungs are developing. Lungs produce surfactant to protect from collapsing and sticking together.

Week 27

The baby’s nervous system is maturing at the 27th week. Your baby is gaining fat.

How quickly does the baby grow in the second trimester?

In the second trimester of pregnancy, your fetus will be about 13 to 16 inches long. It now weighs about 2 to 3 pounds. Fetal development during the second trimester includes-

• Your baby starts hearing sounds from outside.
• Your baby will have fingerprints and footprints by the end of the second trimester of pregnancy.
• The Baby’s face looks more human and the head has hair.
• The babies begin to develop some antibodies.
• By the end of 5th month, the baby is half the length of a new-born.
• Lungs are developed and early breathing movement begins.
• The fetus develops reflexes like swallowing and sucking.
• The brain develops in the second trimester of pregnancy.
• The baby starts sleeping and waking up.
• Rapid growth in fetal size and weight.
• The baby responds to certain stimuli.
• The baby’s sex is clear.
• The baby’s digestive system will start to function.

What things should be managed during the second trimester?

In the second trimester, fetal development day by day is very important. During this phase, you need to take many precautions for proper fetal development.

What to do

• Continue to take prenatal vitamins
• Exercise regularly
• Eat a nutritious diet high in fruits, vegetables, low-fat protein, and fiber.
• Drinking a lot of water.

What to avoid

• Avoid strenuous exercise
• Avoid caffeine and alcohol
• Quit Smoking
• Avoid raw fish consumption
• Avoid unpasteurized dairy products consumption

When to consult a doctor?

You must visit your doctor for regular check-ups during the second trimester of pregnancy. During the second trimester of pregnancy, the doctor checks fundal height, fetal heartbeat, swelling, weight gain, blood pressure, urine protein levels, and glucose levels. You should see your doctor immediately if you experience vaginal bleeding, severe headache, abdominal pain, and vomiting.

The bottom line

Fetal development happens rapidly week by week in the second trimester of pregnancy. By the end of the second trimester of pregnancy the baby’s hearing, heartbeat, breathing, and all other functions start. The fetus now begins to grow in length and weight.