Size:

Length: Less than .1 inch (1.5 mm)

The first month of pregnancy is actually the 2 nonpregnant weeks after you started your last period, plus the first 2 weeks you are pregnant.

• About 2 weeks after your last period started, a sperm joined with an egg in your fallopian tube. The fertilized egg quickly grew into a tiny ball of cells.
• About 6 days after it started growing, the ball of cells attached to the wall of your uterus. (This was about 3 weeks after your last period started. We call this "3 weeks of pregnancy.")
• At 4 weeks of pregnancy, the cells have flattened into a three-layered disc. Each layer has different types of cells. These are the building blocks that will quickly grow into an embryo's organs, tissues, and bones.

This is a critical time for staying away from drugs, alcohol, radiation, and other chemicals. These things change how cells grow.

Size:

Length: About .5 inch (11-14 mm), head to buttocks (crown to rump)

The second month of pregnancy is a time of amazing development for the tiny embryo.

• The embryo starts out looking like a tiny seed, then a tadpole with a tail, and then more human by the end of the month.
• When you are 6 weeks pregnant, your embryo has the beginnings of a brain, eyes, ears, heart, lungs, liver, and other organs. There are tiny bumps where arms and legs will grow.
• When you are 8 weeks pregnant, the heart and brain have divided into their major parts. Your embryo has webbed fingers and arms that bend at the elbow. The legs and feet will take a little more time to grow. Muscles will soon start working.

This month is a critical time for staying away from drugs, alcohol, radiation, and other chemicals. These things change how cells grow, while your baby's brain, heart, arms, legs, eyes, ears, and other organs start to take form.

Size:

Length: 2.4 inches (61 mm), head to buttocks (crown to rump)

Weight: .5 ounces (13.3 g)

• When you are 10 weeks pregnant, your embryo has nearly all of the body structures that an adult has. The brain is now more complex. After this point, we call this tiny being a fetus.
• This month, the tiny fetus starts moving the head and jaw, grasping, moving the tongue, and stretching. Eyelids are covering the eyes, and fingernails are starting to grow.
• At the end of this month, the fetus starts a big weight gain.

This month is a critical time for staying away from drugs, alcohol, radiation, and other chemicals. These things change how cells grow, while your fetus's arms, legs, eyes, ears, teeth, palate, and genitals start to take form and grow.

An important time for testing

• If you are worried about Down syndrome, you may be able to have a special ultrasound and a blood test as early as 10 weeks. If this screening finds signs of possible problems, you have time to decide about more testing.
• When you are 10 to 12 weeks pregnant, you can have a chorionic villus sampling if you are worried about genetic problems. This test can give you some of the same information that an amniocentesis does, but much earlier.

Size:

Length: 4.7 inches (120 mm), head to buttocks (crown to rump)

Weight: 3.7 ounces (104.5 g)

• This month, the face has become more "human." The eyes have moved from the sides of the head to the front. The ears have moved from the neck to the sides of the head.
• By the end of 14 weeks of pregnancy, sex organs are starting to develop. It will be a few weeks before you can tell a boy from a girl with an ultrasound.
• By now, your fetus may have started thumb-sucking, and is rolling, kicking, and moving around a lot.
• If this is not your first pregnancy, you might be feeling your fetus move. The first flutters you feel are called "quickening." It takes a little longer to happen in a first pregnancy.
• You might now be able to hear the heartbeat with a Doppler heart monitor.

An important time for testing

• When you are 15 to 20 weeks pregnant, you can get a triple or quad serum screen. This is a simple blood test for signs of a possible birth defect.
• When you are 15 to 20 (usually around 16) weeks pregnant, you can have an amniocentesis to check for birth defects and genetic problems.

Size:

Length: 6.3 inches (160 mm), head to buttocks (crown to rump)

Weight: .66 pound (304 g)

• This is a time of very rapid growth, especially from 15 to 18 weeks of pregnancy.
• By now, the head is no longer so big compared to the rest of the body.
• You can see bones on ultrasound by the end of week 17.
• At this size, your fetus is still small enough to change position a lot-from head-down to feet-down, or even sideways.
• If this is your first pregnancy, you will start to feel your fetus move. The first flutters you feel are called "quickening."
• At the end of this month, the fetus starts building up body fat.

An important time for testing

• When you are 15 to 20 weeks pregnant, you can get a triple or quad serum screen. This is a simple blood test for signs of a possible birth defect.
• When you are 15 to 20 (usually around 16) weeks pregnant, you can have an amniocentesis to check for birth defects and genetic problems.

Size:

Length: 8.3 inches (210 mm), head to buttocks (crown to rump)

Weight: 1.33 pound (598.5 g)

• This month, the fetus is still building up body fat and starting to put on a lot of weight.
• At this size, a fetus is still small enough to change position a lot-from head-down to feet-down, or even sideways. You will feel more movement or less movement at certain times of the day and night.
• At 23 weeks of pregnancy, the eyes show rapid eye movement.
• In rare cases, babies survive birth at 22 weeks, but generally, the lungs cannot yet breathe air.

Size:

Length: 9.8 inches (250 mm), head to buttocks (crown to rump)

Weight: 2.1 pounds (950 g)

• For most of this month, a fetus is putting on a lot of weight.
• At this size, a fetus can still move around a lot-from head-down to feet-down, or even sideways. You will notice more movement or less movement at certain times of the day and night.
• At about 24 weeks of pregnancy, the lungs are starting to make surfactant, which helps the lungs breathe air.
• With every week after 22 weeks, a baby is a little more likely to survive after birth. A baby born before 26 weeks is not yet equipped to breathe air. Starting at week 26, the chances of healthy survival get better.
• Around 28 weeks, the eyelids are open, hair is growing well on the head, and fat under the skin is making the skin less wrinkly.

Size:

Length: 11.8 inches (300 mm), head to buttocks (crown to rump)

Weight: 4.4 pounds (1995 g)

• The fetus is putting on a lot of weight this month.
• At this size, a fetus is still small enough to change position a lot-from head-down to feet-down, or even sideways. You will notice more movement or less movement at certain times of the day and night.
• By 32 weeks of pregnancy, light can dilate the pupils in the eyes.
• The lungs and central nervous system are working well enough that a baby born this month can breathe and keep fairly warm with medical support. With every additional week, the chances of healthy survival get better.

Size:

Length: 12.6 inches (320 mm), head to buttocks (crown to rump)

Weight: 5 pounds (2300 g)

• Until week 36 of pregnancy, your fetus is probably still small enough to change position a lot-from head-down to feet-down, or even sideways. You will notice more movement or less movement at certain times of the day and night.
• By the end of this month, the skin is pink and smooth. The arms and legs look chubby.
• If your baby is born at a healthy weight during this month, chances of healthy survival are very good.

Size:

Length: 14.2 inches (360 mm), head to buttocks (crown to rump)

Weight: 7.1 pounds (3230 g)

• Your baby is full-term when you have finished 37 weeks of pregnancy.
• By the time a baby is born at term, fat makes up 16% of body weight. The baby's growth has slowed in the last days before birth.
• At this size, your baby does not have much room to move around. You will probably notice less "big" movement than before.
• Your pregnancy is called "post-term" or overdue when you have finished 42 weeks of pregnancy. This is 2 weeks after your due date. Risks go up for the baby, so delivery is recommended.