Baby Development Month by Month
A baby grows and develops an amazing amount in just nine months. Here’s a short summary of how your baby’s development occurs during pregnancy.
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Month 1 – Week 1-4
After an egg has been fertilized and implants into the uterine lining, a sac grows around it. This becomes the amniotic sac and will hold the amniotic fluid and cushion the embryo. The placenta also forms during this month. This will bring nutrition and support to the baby from the mother.
The face and eyes begin to develop, and the heart begins to beat. By the end of the 4th week, your baby will slightly smaller than a grain of rice! B vitamins play a crucial role in you and your baby’s development and your health during pregnancy. Vitamin B6 and Folic Acid (Vitamin B9) are especially important for early development, so make sure you are getting the right amounts of these.
Month 2 – Week 5-9
At two months pregnant, your baby’s face continues its development. Buds that will eventually be limbs begin to develop. Organs such as the brain, sensory organs, and the digestive tract begin to take shape. The cartilage in the embryo begins to be replaced by bone. By the end of the second month, your baby is about 1 inch long! After about 6 weeks, your baby’s heartbeat can be detected with an ultrasound. It is never too soon to start taking prenatal vitamins and omega 3’s and fish oil to help your baby have a healthy development. The American Pregnancy Association recommends Nordic Naturals’ selection of supplements including:
- Vitamin D3
- Ultimate Omega
- Children’s DHA Xtra
- Artic-D Cod Liver Oil
Month 3 – Week 10-14
The limbs, as well as the hands, feet, fingers, and toes, become well developed. The fingernails and toenails begin to form. The external ears and teeth begin their development as well. Though reproductive organs haven begun to form, they can’t yet be determined on an ultrasound or sonogram. By the end of the 3rd month, your baby is fully formed (with all organs and extremities present), he or she weighs about an ounce and is 4 inches long!
After the 3rd month of development, the chance of miscarriage drops considerably.
Month 4 – Week 15-19
Hair, eyelids, eyelashes, and nails become well developed. The heartbeat is now clearly audible through a Doppler instrument. The teeth become denser, and the baby begins to stretch, yawn and make other movements. The reproductive organs are now visible on an ultrasound. Your baby can now stretch, suck their thumb, yawn, and make super cute faces.
This is the month that his or her nervous system develops. Their reproductive system also fully develops meaning your doctor can tell you whether you are having a girl or boy via ultrasound. By the end of the 4th month, your baby is about 6 inches long and weighs 4 ounces!
Month 5 – Week 20-24
This month you may start to feel the baby move. Hair growth continues on the baby’s head and body. The shoulders and back become covered with a thin hair called lanugo. A thick substance, called vernix caseosa, covers the skin to keep it protected from the exposure to amniotic fluid. This layer will shed before the baby is born. At the end of month 5, your baby is about 10 inches long and can weigh anywhere from .5 lbs – 1 lb!
If your baby is born prematurely after the 23rd week, he or she will be kept in the NICU for a better chance of survival.
Month 6 – Week 25-30
The skin is still translucent yet reddish and wrinkled. His or her fingerprints and toe prints become well developed. The baby’s eyelids become parted, and the eyes can be opened. Your baby will respond to external stimuli such as sounds by increasing their pulse or moving. This is when you may experience your baby’s hiccups in jerk-like motions. At the end of month 6, your baby is about 12 inches long and can weigh close to 2 lbs!
Month 7 – Week 26-29
During this month, your baby will continue to grow and develop the existing organs and systems. In addition, a layer of fat will begin to be stored. At this stage, hearing is fully developed. He or she will react to sound, pain, and light and often changes position. The amount of amniotic fluid that cushions the baby begins to decrease as the baby grows larger. At the end of this month, your baby is about 14 inches long and can weigh between 2 – 4 lbs!
If born prematurely after week 27, your baby has a better chance of survival.
Month 8 – Week 30-34
The baby continues to mature during this month, adding to fat stores and experiencing a rapid development of the brain. The baby can see at this stage and will begin to kick more. Most of the internal organs and systems are fully developed, but the lungs still need time to mature. By month 8, your baby is close to 18 inches long and can weigh close to 5 lbs!
Month 9 – Week 35-40+
The lungs become mature during this time in preparation for birth. Reflexes become more coordinated, allowing the baby to respond to sounds, blink, grasp, and turn his or her head. The baby may move less during the last few weeks and will move into a position for birth, with the head down near the birth canal. Your baby is now about 18-20 inches long and can weigh at least 7 lbs!
A Happy Momma = A Happy Baby
Pregnancy is such an exciting time for mom and baby. Getting plenty of rest, maintaining a healthy, balanced diet and avoiding stress is especially important for you and baby. You can start bonding with your baby during pregnancy in several ways now. Below are some recommended books for you to learn more about how your body changes while your baby develops inside throughout pregnancy. Remember, a happy momma makes for a happy baby.
Recommended Books On Baby Development Month By Month and Pregnancy: