[OnyxCougar]

Week 5:
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.

(This is when pregnancy tests can start picking up the hormone and give a positive reading.)

Week 8:
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.

Week 11:
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.

Week 12:
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.

(source: pregnancyguideonline.com)


After 12 weeks (the first trimester) it is medically a "fetus" and a little person in there. Before that time, it's classified as an embryo, basically, a clump of cells.

Most states (check yours) specify that 12 weeks is the latest abortion is allowed except for medical reasons. It's also much more expensive and difficult on the mother's body, because instead of vaccuuming the baby out (D&C), they have to hack it up first due to the bones getting more dense.

from religioustolerance.org
First trimester surgical, and medically induced abortions: Most abortions are elective procedures performed sometime during the first two months of pregnancy when the fetus is one inch or less long. Over 90% of abortions are done during the first trimester (i.e. the first three months). They total about 1.2 million/year in the US -- a number that is gradually decreasing. In almost all cases, there is no medical reason why the pregnancy needs to be terminated. The abortion is chosen simply because the woman does not want to have a baby.

edit: changed zygote to embryo.