Fetal Development – Month By Month Guide


Baby’s Development Month by Month

Intrauterine development of the baby was a mystery until recently. Even today, there are many unknown facts related to fetal development, in spite of the scientific and technical advancements. It is fascinating how a simple microscopic cell evolves over a period of nine months to become a fully developed baby.

One resource that many pregnant women turn to is a guide that depicts the development of the fetus. It’s exciting to see and read about what the baby looks like and how the body is developing. Each month brings new and thrilling changes.

Pregnancy Month by Month

Month 1

Conception occurs when the egg gets fertilized by a sperm. The cell that is formed by this merger is called zygote, which undergoes cell division and gets implanted in the uterine wall forming an embryo.

During the First Month i.e. first 4 weeks of pregnancy a woman isn’t showing yet and really hasn’t begun to feel any of the major changes that accompany pregnancy. Her breasts may be a bit tender and she may have a bout of morning sickness, but the baby has yet to grow enough for her to feel or see it. During the first month, the fetus is very small, on average about a quarter of an inch like a Poppy seed.

month 1 fetal developement

Month 2

The second Month (week 5 to 8), is often when a woman really realizes she is pregnant. Many women have irregular menstrual cycles so they don’t seek medical advice until they’ve missed a second period. In the first 2-8 weeks of pregnancy, the embryo grows very quickly. From this period begins the cell division that favors the formation of organs. This is the period of maximum vulnerability for the embryo.

All organs are forming now – face (mouth, nose, eyes, teeth buds), liver, kidneys, digestive tract, upper and lower limb buds. Also now begin to develop sexual organs. At eight weeks the embryo is about 2-3 centimeters and weighs about 2 grams. You should consult your doctor about caution regarding exercise, food, medicines and drinks to reduce the risk of miscarriage in this period. By end of Month 2 fetus size is normally similar to a Raspberry.
month 2 fetal developement

Month 3

During the third month (Week 9 to 13), the expectant mother may begin to show visible signs of pregnancy. Her clothes will become tight and she’ll turn to the maternity clothing aisle for her wardrobe. At the end of the third month of pregnancy the fetus is about 5.5 cm and 14 grams. At this time of pregnancy, baby’s sex can be determined. Most body functions are formed: baby eats and breathe through the placenta. Baby also begins to grow nails, fingers and toes. The expecting mom still does not feel fetal movements.
By end of Month 3 fetus size is normally similar to a Peach.
month 3 fetal developement

Month 4

Fourth month (week 14 to 17) of pregnancy is the beginning of second trimester. During this period the head and body hair appears in the fetus. The fetus begins to resemble more and more a human being. The baby’s skin is very pale, translucent pink. The fetus begins to practice breathing. She can move her mouth and feet. Ears and vocal cords are developing. By the end of the fourth month the fetus has grown to about 13 cm and 140 grams. Many pregnant women believe that this is the best time of pregnancy.
By end of Month 4 fetus size is normally similar to an Onion.
month 4 fetal developement

Month 5

The Fifth Month (week 18 to 21) also brings some changes to both the mother and the fetus. Her increasing waistline is a clear indicator that the baby is growing. During this month the fetus also develops hair. One of the most amazing events for the expectant mother during the fifth month of pregnancy is that she will begin to feel the baby moving inside of her.

This is truly amazing for both parents as the father can now truly share in the experience by placing his hand on the woman’s stomach to feel a “kick”. By the end of the fifth month, the fetus will have grown to about 25 centimeters and 450 grams. The fetus is fully developed, and ready to gain weight and grow in height in the next periods of pregnancy.
By end of Month 5 fetus size is normally similar to Cantaloupe (or Banana).
month 5 fetal developement

Month 6

By the Sixth Month (week 22 to 26) the fetus is well developed and is averaging a length of about 35 centimeters. The fetus also weighs close to 900 grams and will be active during certain parts of the day. One funny note during the sixth month of gestation is that the fetus can hiccup, a trait that lasts for an entire lifetime.
By end of Month 6 fetus size is normally similar to an Eggplant.
month 7 fetal developement

Month 7

The Seventh Month (Week 27 to 30) is when the mother really begins to anticipate the arrival of her new baby. It’s steadily growing and changing each day. Its weight will have increased to 1,500 grams by this point and it may be up to 40 cm long. The baby is now fully formed and can recognize hearing his mother’s voice. Baby’s eyes are fully formed; only lungs need time to be fully developed. Babies born at this stage can survive but they are considered premature and will need lots of extra care and attention. They will also have to spend weeks in the hospital as their bodies mature and develop.
By end of Month 7 fetus size is normally similar to a Squash.
month 7 fetal developement

Month 8

The Eighth Month (week 31 to 35) brings with it still more exciting changes. This month the baby will grow by leaps and bounds and may reach a weight of up to 2500 grams and length of 51 centimeters. The baby’s brain really develops during this month as well. When the baby kicks it’s even possible for others to notice the mother’s stomach moving. She can sit still and her stomach will move all by itself. Well actually, it is the baby’s movements causing the commotion.

Baby eyes will stay open when she is awake and closed when she sleeps. Baby’s sleeping hours often do not coincide with those of the mother. Therefore, the mother may have insomnia caused by increased activity of baby during the night.
By end of Month 7 fetus size is normally similar to a Honeydew.
month 8 fetal developement

Month 9

Once the Ninth Month (week 36 to 40) arrives everyone, including the baby, is ready for the big day. The baby continues to grow and gain weight, reaching dimensions term average of 3.5 kilograms and 51 centimeters. The process of brain development is not completed, but it continues during childhood and adolescence. The baby will move into the head-down birth position. All of its organs have matured and it is ready to enter the world kicking and screaming. By end of Month 9 baby’s size is normally similar to a Watermelon.
month 9 fetal developement

Starting with 37 weeks, birth can trigger anytime, so during the ninth month of pregnancy you should go for weekly medical checks and get familiar with the first stages of labor, so that you can call your obstetrician and get yourself admitted to the hospital for delivery.

Beautiful video showing how a baby develops during pregnancy.

Getting the regular scans done during pregnancy is very important for a trouble free pregnancy and delivery. The above given information for baby’s development month by month during pregnancy is general information.


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