fetal development library

Fetal Development answers your questions about the changes that take place in the womb during pregnancy. Learn about each of the three trimesters and the developmental milestones that occur in each.

Conception

Featured Article: Conception

Sperm plus egg equals zygote. That’s the simple story. There’s actually a lot more to it than that. A whole lot more. Watch this detailed animation to see exactly what happens during conception. See more »

Conception

Conception

Sperm plus egg equals zygote. That’s the simple story. There’s actually a lot more to it than that. A whole lot more. Watch this detailed animation to see exactly what happens during conception.

See more »

Placental Formation

From the earliest stages of its development, the growing embryo requires nutrition, oxygen, and waste removal. All of this is accomplished by the placenta.

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How A Fetus Grows

The journey of the fetus through pregnancy is a complex and fascinating miracle that scientists have broken into three phases -- the three trimesters that represent a nine-month pregnancy. Learn how a fetus grows

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Embryonic and Fetal Development

Watch the development of the embryo from weeks 3 to 8 and the development of the fetus from weeks 8 to 40.

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Fetal Ear Development

During the fifth month, the baby's outer ears are almost fully developed. Watch how they form.

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Formation of twins

Twins are rare and special, and they happen in about 1% of all pregnancies. 30% are identical and 70% are fraternal twins.

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Heart Formation

The heart is the first organ to form in a fetus’ body. Watch how it develops over nine months.

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How does the baby come out?

How can you explain how babies come from inside the mother to the outside world? This kid-friendly animation gives a simple overview of labor contractions and birth.

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How does the baby eat and breathe in the uterus?

While the baby is living inside the mother's body, she nourishes it through the umbilical cord. This simple animation shows how a baby gets nutrition while inside the womb.

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Human Face Formation

The development of the face is a fascinating process that has many changes taking place over a short amount of time.

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Makin' Babies

Whether you're trying to explain the "birds and the bees" to your five-year-old or you and your spouse are wondering how to decipher that ultrasound image of your soon-to-be child -- this is the page for you.

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Nervous System Formation

The most critical stage of development for the embryo’s nervous system are the third and fourth weeks of pregnancy.

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Pregnancy

This animation illustrates the many changes that occur in both the mother and developing baby during the three stages or trimesters of pregnancy.

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Skeletal Formation

A baby’s skeleton begins as fragile membranes and cartilage, but after three months start turning into bone in a process called ossification.

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Ultrasound

Ultrasound is one of the most useful procedures in monitoring the baby’s development in the uterus.

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Understanding Ultrasound Fetus Images

To the untrained eye, it can be difficult to make any sense of an ultrasound image. This interactive animation demonstrates how a fetus would appear at different stages of pregnancy.

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Where do babies come from?

Need help explaining where babies come from? This simple animation gives a kid-friendly overview of how babies are made.

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Will the baby be a girl or a boy?

The creation of a zygote is a complex process. Watch what happens as sperm and egg combine to create offspring. This animation walks you through the process.

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