Your uterus has shed its lining through your period and is now preparing a lush new bed of blood-rich tissue designed to house a growing fetus. Your eggs are ripening in one of the ovaries and preparing to release one.

Sperm meets egg within the fallopian tube and the miracle of life begins. Although several sperm may penetrate the egg's outer layer, only one sperm will enter the ovum and fertilize it. In the middle of the ovum, the chromosomes of mother and father splash about and bits of information from both begin to form the chromosomes of your baby. At the moment of conception, your baby's gender is determined thanks to the sex chromosomes in the father's sperm. If you don't like the gender of your baby, blame dad.

Taking root! Implantation occurs. Once the blastocyst gets to the uterus, it searches for a spot to settle down. Blastocyst means "sprout pouch," and these cells begin to divide into two groups - those that form the placenta and those that form the baby. The blastocyst will burrow itself into the lining of the uterus which is called implantation.

The developing embryo has three layers. In the top layer (ectoderm), the neural tube will form which will further develop into the nervous system (brain, spinal cord, skin and hair). In the middle layer (mesoderm), the heart and circulatory system, bones, muscles, kidneys and reproductive organs will develop - eventually. At this stage, however, the heart and primitive circulatory system will rapidly form. In fact, the circulatory system is the first organ system to function. In the inner layer (endoderm), a simple tube will develop into the intestines, liver, pancreas and bladder.

My Heart Belongs to You! The first heartbeats have begun! The baby is now an embryo and is about 1/17 of an inch long. Growth is very rapid this week. The umbilical cord develops. The eyes and ears begin to form as well as an opening for the mouth. The heart has begun to pump blood and most of the other organs are well under construction. Buds form on the body that will become the arms and legs.
Exciting week!

I'm Tiny But Gaining Fast!
The baby is about 1/3 of an inch, the size of a grain of rice. Development of the arms and legs continue although the fingers and toes haven't yet formed. The brain is growing as well as the lenses of the eyes, nostrils, intestines, pancreas and bronchi

An ultrasound done at this stage should show a fluttering heartbeat. Elbows begin to form in the arms and fingers start to develop. The leg buds begin to show feet with tiny notches for the toes. The face continues to change as the ears, eyes and the tip of the nose appear. The intestines start to form in the umbilical cord. Teeth develop under the gums.

Cartilage and bones begin to form. The basic structure of the eye is well underway and the tongue begins to develop. The intestines start to move out of the umbilical cord and into the abdomen as the body grows and makes room. The fingers and thumb have appeared but are short and webbed.

I'm Swimming! The baby has begun moving inside the womb although it's too small for mom to notice. Most of the joints are formed now - elbow, wrist, knee, shoulder, and ankle as well as the hands, fingers, feet and toes.

Changes in Mom

The morning sickness may start to ease a bit. This week, we'll blame moodiness and a blotchy complexion on those wild hormones. Have heart ~ this is only temporary.

I'm a Fetus!

Starting with this week, the baby is now called a fetus. The most critical part of the baby's development is over. This is a period of rapid growth, and the baby is about an inch or so in length at the beginning of the week and will be about 2 inches by the end of the week. The baby's head is about half its length. The eyelids will fuse shut, and the irises will begin to develop. Sometime during this week or the next week, blood will begin to circulate between the baby and uterus and the placenta starts to function.

Changes in Mom

Your uterus is the size of a small grapefruit already! You may find that your appetite is better as your nausea subsides even though certain smells may bother you.

By this point, nearly all of the organs and structures of the fetus are formed. They will continue to grow and develop until delivery. Fingers and toes have separated and hair and nails begin to grow. The genitals begin to take on their gender characteristics. Amniotic fluid begins to accumulate as the baby's kidneys begin to produce and excrete urine. The muscles in the intestinal walls begin to practice peristalsis - contractions within the intestines that digest food.

Changes in Mom

Around this week, your uterus will shift up and forward as it grows. The good news is it won't be pressing on your bladder so much and those bathroom visits will get less frequent. Enjoy this while you can because by the third trimester, the uterus will grow large enough to sit on your bladder once again. Morning sickness is usually getting better by this time, and you may be less tired. Headaches and light-headedness are common now thanks to the increased blood volume but be sure to discuss these symptoms with your care provider.