Themes

Featured Shows

Hooked

Best of Nat Geo in HD

Wild

Locked Up Abroad

DogTown

Taboo

CIA Confidential

Explorer

Inside

Dog Whisperer

Lockdown

Man-Made

World's Toughest Fixes

Dangerous Encounters

Naked Science

America's Wild Spaces

Specials

Hitler's Stealth Fighter

Iran and the West

Secret Lives of Jesus

The Pirate Code

July 4: Exploding the Myths

Who Is the Tribe in the Picture?

Secrets of Jerusalem's Holiest Sites

Secrets of the Knights Templar

Science of Summer

Devil's Bible

Decoding the Dead Sea Scrolls

Doomsday: Book of Revelation

In the Womb: Multiples

OverviewOverviewVideoVideoFactsFactsTime LineTime Line

In the Womb: Multiples

In the Womb: Multiples utilizes groundbreaking technology to take viewers into the extraordinary world of twins, triplets and quadruplets as they develop in utero.

In the Womb: Multiples , Multiples' Womb , Identical twins can each be of a different sex.

In the Womb: Multiples , Inside the Womb , Images show multiple babies inside the womb.

Womb-Multiples_HTML_facts

Facts

Twins are positioned beside one another in the womb

About 95 percent of all multiple births in the United States are twins.
34 out of every 1,000 births in the United States are multiples.
Between 1980 and 1998, the rate of triplets and higher order births in the United States increased by 400 percent. In recent years, this rate has been more stable.
A woman has an estimated one in 64 million chance of conceiving identical quads.
Women reaching the end of their reproductive years are more likely to have a multiple pregnancy.
The window for an egg splitting to form identical twins is very short. If the egg doesn?t split into two separate but identical eggs within the first 14 days after conception, it never will.
The record number of fetuses in a human womb at one time is 15.
It?s estimated that for every 400 sets of fraternal twins, one set is made up of twins who will have different fathers.
At birth, single babies on average weigh more than twins.
Some fetuses spend the first trimester of pregnancy with a companion that later disappears—a phenomenon called the ?vanishing twin syndrome.?
Movements such as kicking, pushing, and what looks like kissing are all documented in twins.
Interaction between twins may be beneficial, helping to accelerate their development.
About half of twins are delivered by Caesarean section (or C-section).

Womb-Multiples_HTML_time-line

Time Line

First Month

During the first two weeks after fertilization, the egg can split into identicals.
Seven to 10 days after fertilization, the egg or blastocyst implants into the uterine wall.
Ten to 14 days after fertilization, the egg, now considered an embryo, is about the size of a poppy seed.
At 21 to 22 days, the heart begins to beat.
The embryo is approximately 0.01 inches (0.36 millimeters) long, smaller than a grain of rice.

Second Month

The brain is creating 2.5 million brain cells every minute it is in the womb; it will have more than 100 billion cells by the time the baby is born.
The uterus expands from the size of a lemon to the size of a grapefruit. The uterus has the ability to ultimately expand to the size of a large watermelon.
The embryo is a little more than half an inch (17 millimeters) long, or the size of a lima bean.

Third Month

Almost all of the parts of the body have formed—eyes, ears, nose, fingers, arms and legs—and continue to grow.
The embryo is now a fetus, weighing 1.5 ounces (42.5 grams) and measuring approximately 2.5–3 inches (6.4–7.6 centimeters).
A mother-to-be will go for her first ultrasound scan at 10 to 14 weeks into the pregnancy.

Fourth Month

The womb is now the size of a small melon. The placenta, the organ that processes food and oxygen for the fetus, is fully functioning.
Arms and legs are fully formed and moving. The mother may begin to feel the fetus' movements, sometimes called "quickening."
The brain is developing neural pathways that allow the fetus to sense other parts of the body and elements in its environment. As the fetus begins to move, it also develops an awareness of the space around it. This awareness or proprioception helps humans navigate the constantly changing world around us. Twins and higher order births develop this sense with the help of their siblings when one kicks or moves and another fetus responds.
The digestive system begins to function and the fetus learns to swallow by drinking some of the amniotic fluid. Some of the flavor from the mother's food will be transferred into the amniotic fluid and can influence the development of taste buds. Since multiples are sampling the same foods in the womb, they may have similar tastes in foods once they grow up.

Fifth Month

A single fetus is halfway to birth, weighing almost one pound (0.45 kilograms) and measuring 7–9 inches (18–23 centimeters).
The fifth month is an important time for a fetus to grow, but for multiples, the presence of two or more fetuses means room to grow is limited. To decrease the likelihood of premature birth, the growth rate for multiples gradually slows after five months in the womb.
A male fetus' penis and scrotal sac are enlarged and look like they are growing out from the fetus' abdomen, and are visible on an ultrasound exam. The testes will not descend until the end of pregnancy.

Sixth Month

The growth rate of multiples tends to slow.
A female fetus' ovaries are developing all the egg cells she will have throughout her lifetime.
The fetus' eyes open for the first time.

Seventh Month

Hair is growing and beginning to develop the color it will have upon birth. Nails have formed on the fingers and toes.
Triplets' growth rate tends to slow. Triplets are frequently born at 34 weeks.

Eighth Month

Twins' growth rate tends to slow.

Ninth Month

Many twins are born at 36 weeks.
The umbilical cord, the baby's lifeline, has grown to almost 2 feet (0.6 meters) long, and the placenta weighs about 1.5 pounds (0.7 kilograms).

Themes

Featured Shows

Specials

In the Womb: Multiples

Ultimate Vette

WORLD WITHOUT HUMANS

HUMAN MACHINE