How your Baby is Developing Week by Week in the Early Stages of Pregnancy

How your baby is developing
Pregnant woman looking at her baby sonography

You probably spend a great deal of time during the early days of your pregnancy wondering what the baby looks like and how he or she is developing. When will you feel the baby move, and how long until they can hear you?

While these dates are estimations, here’s a look at the first few months of pregnancy, and how your baby is coming along week by week.

Weeks one to four 

During the first month after conception, the fertilized egg moves through the fallopian tubes towards your uterus and attaches to the uterine wall. This is known as implantation. Once the egg is implanted, it begins to grow and the placenta forms.

Week five

Have you been getting your folic acid? In the first few weeks of pregnancy you should be eating foods that are rich in folic acid (or folate), including dark green vegetables (broccoli, spinach, peas, and Brussels sprouts), corn, dried peas, beans, lentils, and oranges.

This nutrient is essential to the formation of your baby’s neural tube which becomes the brain, skull and spine. This forms at about the fifth week of pregnancy. At the same time, your baby’s heart and lungs are forming, and the heart begins to beat.

Weeks six to eight

Over the next couple of weeks, your baby’s organs will form, and bones will develop. The heartbeat can be heard on an ultrasound at about six weeks of pregnancy. Tiny buds for the limbs appear with webbed fingers and toes. Your baby’s eyes, ears, and nose begin to develop. Eyelids form shortly after, and they remain closed at this phase.

By the end of your eighth week of pregnancy, all of the baby’s major organs and body systems have begun to develop.

While you may not look pregnant at this point, you will be feeling it. Common pregnancy symptoms include morning sickness – which is nausea or vomiting that can actually occur at any time of the day, changes in appetite, suddenly craving an unusual food or disliking something you normally enjoy, as well as fatigue.

Weeks nine to twelve

Your baby is developing fast now. Buds for their future teeth appear, and their individual fingers and toes begin to form along with soft nails. The baby’s bones and muscles develop, and their intestines begin to form.

By the twelfth week, the baby can move around, although you probably won’t feel it yet at this point. The baby will only be about five centimetres long and weigh about 14 grams or half an ounce.

Into the second trimester

By week thirteen, the baby already has his or her own unique fingerprints. They will be growing fast now, and your abdomen will start to expand as the baby gets larger. Fortunately, the feelings of fatigue and nausea should subside by now.

By week fifteen, your baby will start to be active, and you may begin to feel them moving around. They will alternate between periods of sleep and wakefulness. They can also hear you now, so you can tell them stories or sing songs for them. By week eighteen they should be moving around a great deal.  

By week eighteen an ultrasound may be able to determine the sex of your baby, so you will have to decide going in if you want to know this information or not.

Fetal development generally follows a fairly predictable schedule, but of course the exact timing can vary between expecting mothers. That is why these dates are estimations. You should consult with your healthcare provider if you have any concerns about your baby’s development or questions about the nutritional and lifestyle choices you should be making along the way to ensure a healthy birth.

Peter Harris

Peter Harris is a marketing, branding, and careers expert. He began his career as a travel writer and advertising copy writer, and went on to build the original Canadian content for, serve as the editor-in-chief of Workopolis, and deliver the country its daily news and features as the homepage editor of Yahoo! Canada. He writes and speaks frequently on career, workplace, education, and technology issues as well as on trends and changes in the Canadian job market. He is the co-founder of Yackler, a content marketing start-up, and the father of a challenging, funny, elementary school-aged son.

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