Many congratulations on the arrival of a little one to complete your family. You and your partner must be extremely excited about embarking on this beautiful journey of motherhood, and you must also be curious about how your baby will grow and develop inside you.

First-time mothers have millions of questions about the baby developing inside them, how it will grow, and will you be able to feel its movements. Now, you can always take a little peek at the ultra-sound, but we’ve created this comprehensive guide to walk you through all the developmental phases of the life growing inside you.

Fetal Development by Month
Credit: MedMD

Here’s everything you need to know about your baby’s growth, from conception to birth:


Fertilization takes place when a sperm comes in contact with an egg and successfully penetrates it, experts also refer to this as conception. When this takes place, it completes the entire genetic makeup of the baby, even its sex. It takes nearly three days following the conception for the fertilized egg to quickly begin dividing into multiple cells.

Then, it gets transfers into the uterus by passing through by fallopian tube, and finally, it becomes attached to the uterine wall. Finally, the placenta starts to develop, which basically nurtures and nourishes the baby.

Development at 4 Weeks

After four weeks are complete, your baby’s structures have started to develop, and his neck and face have emerged. At this point, the heart and the blood vessels are still developing, while the liver, lungs and stomach have begun to form. If you take a pregnancy test at four weeks, it will read positive.

Development at 8 Weeks

At 8 weeks, your baby is likely to be little more than half an inch long, and its ears and eyelids have started to form.

You can even see the tip of its nose, along with well-formed legs and arms. The toes and fingers also become for evident and grow longer.

Development at 12 Weeks

At this point, your baby is nearly 2 inches tall and it will make itself noticed by making tiny movements of its own accord. You will begin to feel that the top of your uterus has risen atop of your pubic bone.

Moreover, with the help of certain instruments, your doctor will be able to detect the heartbeat of the baby, and the sex organs will also become more evident.

Development at 16 Weeks

At 16 weeks, the baby is likely to 4.3-4.6 inches tall, and nearly 3.5 ounces heavy, which is why you’ll be able to feel your uterus top nearly 3 inches beneath your belly button.

Now, the heart and blood vessels of the baby are well-formed, and its eyes can blink. Moreover, it’s toes and fingers have also developed their fingerprints.

Development at 20 Weeks

Now the baby is nearly 10 ounces heavy and its height is likely to be a bit more than 6 inches. By this time, you can feel your uterus levelled up with you belly button. During this period, women are like to experience quickening, which is basically the sensation of your baby moving inside you.

The baby is now capable of yawning, sucking its thumb, making facial expressions and even stretching in your belly.

Get Ready for the Ultrasound

The doctors usually perform an ultrasound for women who are at least 20 weeks. This ultrasound will allow the doctor to ensure whether the placenta is attached adequately and if it is healthy, along with ensuring the healthy growth of the baby inside you.

The ultrasound will allow you to feel the heartbeat and movement of the baby, legs and arms. At 20 weeks, you can also find out if your baby is boy or a girl.

Development at 24 Weeks

At this point, your baby is nearly 1.4 pounds heavy and it is capable of recognising sounds, which can be indicated by its movements or an increase in the baby’s pulse.

You can detect tiny movements if the baby takes hiccups. Moreover, the baby might even be capable of sensing that it is upside down within your womb as the inner ear is well-formed at 24 weeks.

Development at 28 Weeks

At 28 weeks, the baby should weigh nearly 2 pounds and 6 ounces heavy, and it is capable of changing its positions within the womb. If a woman has had to make a premature delivery at 28 weeks, it is highly likely that the baby would be born healthy and normal. However, it is better to prevent this and you can always consult your doctor about all the preterm labour symptoms so you can prevent it.

Also, it is highly advisable for you to sign up for birthing classes at this point. Attending some birthing classes will help you prepare yourself for all the complications related to childbirth, such as labour, the process of delivering your baby and of course, looking after your new-born baby.

Development at 32 Weeks

At 32 weeks, your baby is nearly 4 pounds heavy and you can feel a lot of movement because the baby is often changing its positions. Layers of fat are beginning to emerge under the baby’s skin, which will make its skin less wrinkly and smoother. From this point until the delivery, your baby is likely to gain nearly half of its birth weight.

Be sure to consult your doctor about making a fetal movement chart, along with understanding the dynamics of breastfeeding. At this point, you will be able to detect the emergence of a yellowish fluid emerging out of your breasts, which doctors refer to as colostrum.

The colostrum occurs to basically indicate that your breasts are preparing to create milk. At this point, it is essential to make an appointment with your doctor after every two weeks.

Development at 36 Weeks

It is essential to understand that the overall growth rate of your baby is just as essential as the actual weight because babies also tend to differ in sizes as they size is influenced by several factors. For instance, the number of babies the mother is carrying, the size of its parents, and of course, the gender of the baby itself.

Research reveals that the average size of the baby at 36 weeks should be nearly 18.5 inches, and its weight should be around 6 pounds. At this point, the brain of the baby is fastly developing, and its lungs are fully formed. The head of the baby should be faced downwards into your pelvis, and when you have completed 37 weeks of your pregnancy, your baby will be considered at ‘term.

Basically, if your baby is born during the 37-39 week period, it will be an early term baby, if you give birth between 39-40 weeks, it will be at term, and if it’s born during 41-42 weeks, it will be a late term baby.

Time to Give Birth!

At the end of the 40th week, mothers are likely to mark deliver the baby. You can calculate your delivery date by using the first day you got your last period. Based on your last period, your pregnancy is likely to last for 38-42 weeks, while a full-term delivery tends to take place after 40 weeks are complete.

There are certain post-term pregnancies, which tend to last more than 42 weeks, but they’re not considered too late. It is likely that the due date might be incorrect, but doctors always deliver the baby by the 42nd week in order to keep both, mother and child safe. In certain circumstances, doctors are left with no choice but to induce labor.


Women & Infants Hospital of Rhode Island: First Trimester

Mayo Clinic: Pregnancy Week by Week

Office on Women's Health: Stages of Pregnancy


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