What are the Stages of Fetal Development?

Sarah Johnson
8 Min Read

You and your baby have an incredible journey ahead during your pregnancy; in the nine months, the fertilized egg is divided, grows, and develops until your baby gets ready to greet the world and become a part of your family. An average pregnancy will last for around 40 weeks or about nine months. Three trimesters, each lasting roughly three months, make up the entire duration of pregnancy.

Every day, a fetus will spend in the womb for its healthy development until it reaches full term or at least 37 weeks of pregnancy. Modern medicines have made great strides in caring for infants, and the womb is the best place for the baby’s growth. Not all premature babies have health issues, and those born close to their due date have improved outcomes. Here we tell various stages of fetal development.

The Start of Your Pregnancy

Every month during a woman’s childbearing years, an egg matures within the ovary inside the cyst known as a follicle. When the follicle releases the, e.g., in the fallopian tube, it is known as ovulation. The ovulation mainly occurs two weeks into the monthly cycle of a woman. Most of the months, the eggs are not getting fertile by the sperm, and the lining of the uterus gets shed by the vagina into the average menstrual period.

The egg gets fertilized, and this is known as conception. The fertilized egg is mainly known as a zygote, and it divides rapidly into several cells and becomes a blastocyst. It mainly stays in the fallopian tube for around three days and begins its journey to the uterus.

stages of fetal development by trimester

Stages of Fetal Development

When you talk to people studying genetics and fetal development, they look at pregnancy differently. The stages of fetal development by week that they look at are:

  • The germinal stage (weeks 2 to 4)
  • The embryonic stage (weeks 5 to 9)
  • The fetal stage (week 10+)

The Germinal Stage (Weeks 2 to 4)

It is the early stage of development, which is mainly known to most people. It starts when the egg and sperm meet up in the outer third of the fallopian tubes. When the two become one, a zygote results, and it will continue its journey toward the uterus. During this time, the body doesn’t recognize the pregnancy, and it will take seven or more days to travel the tube length and deposit the fertilized egg into the waiting uterus.

The Embryonic Stage (Weeks 5 to 9)

The cells are not considered as the embryo, and now they are distinctly human in origin, and the embryo doesn’t look like what most of us picture when we start thinking about a baby. The embryonic period is quite critical as every organ system is formed.

The Fetal Stage (Weeks 10+)

The fetus is a term which is heard by most of the people. It is the technical name for the baby who is in the fetal state. The fetal stage is less exciting, and everything is present. To get the fetus ready for life outside the womb, there are a lot of refinements and adjustments to make..

The fetus will go from being a one-gram, one-inch being to weighing roughly seven pounds and being approx. Twenty inches long, but the fetal stage is also growing in weight and height.

The organ system needs lots of nuanced changes. The baby’s brain will grow in size and shape, but it is not until the last weeks that the fields of the brain will deepen, and the weight gain into the brain is significant as well.

Fetal Development in the First Trimester

During the first three months of pregnancy, your baby will develop from an egg to a fertilized egg or zygote to a blastocyst or an embryo and then into a fetus. The tasks that are available during the first trimester or stages of fetal development by month generally include the following:

  • Ultrasound: In the first trimester, a nuchal translucency screening by ultrasound will help the doctor assess the baby’s risk of abnormalities. To verify the due date, find out the number of fetuses present, and assess the condition of your uterus and cervix, an ultrasound or photos depicting the phases of fetal development are required..
  • Blood Tests: The tests will measure the plasma protein and the human chorionic gonadotropin.

Complications With Fetal Development

Some things can alter the course of healthy fetal development at the genetic level, and physical issues can interfere. Sometimes, these problems will halt the process altogether, and the baby will stop growing, likely into the germinal stage when the mother doesn’t know that she is pregnant or into the embryonic stage, where she may or may not know that she is pregnant.

Final Verdict

In the above-given article, we have finally covered all the details about the stages of fetal development. We hope this article becomes valuable and helpful for you in understanding all the stages of fetal development. If this article benefits you, please share it with others to make it beneficial for them as well.

Also Read Blog: Secondary Infertility Causes


How many stages of fetal development are there?

Between conception and delivery, there are lots of detailed steps that occur. There are mainly three main stages of fetal development: germinal, embryonic, and fetal.

What are the four stages of embryo development?

The four stages of fetal development during pregnancy are fertilization, blastocyst and implantation, and embryo and fetal development.

When does the fetal stage begin?

At the beginning of the 11th week of pregnancy or the ninth week after conception, your baby’s head will make up about half its length. Your baby’s body is about to catch you, and your baby is now described as a fetus officially.

What is the definition of the fetal stages?

The time during pregnancy during which fetal growth and development take place is sometimes referred to as the fetal period.. The stages of fetal development by trimester and the fetal period begin after ten weeks and then end when the baby is born. The fetal period is one of the longest stages of development during the pregnancy.

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Sarah Johnson, loves helping expecting parents on their journey to parenthood, Sarah has lots of knowledge about her work as a maternity and fertility specialist. She provides personalized care and support to individuals and couples in the path of conception and pregnancy. She writes engaging blogs and articles at pregnancycounselors.com about maternity and fertility. From tips for boosting fertility to handling the ups and downs of pregnancy, her blogs are full of valuable information for women.
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