Since abortion advocates must concede that abortion kills a living human being, many try arguing that embryos and early fetuses aren't developed enough to be morally significant. The following timeline will help put such claims in better perspective.
FERTILIZATION
At the moment of fertilization, a new and unique human being comes into existence with its own distinct genetic code. Twenty-three chromosomes from the mother and twenty-three chromosomes from the father combine to result in a brand-new and totally unique genetic combination. Whereas the heart, lungs, and hair of a woman all share the same genetic code, her unborn child, from the moment of fertilization, has a separate genetic code that is all its own. There is enough information in this tiny zygote to control human growth and development for the rest of its life.
EIGHT DAYS (from fertilization)
At about eight days after conception, the fertilized ovum (called a blastocyst) implants in the lining of the uterus. It emits chemical substances which weaken the woman's immune system within the uterus so that this tiny "foreign" body is not rejected by the woman's body.
THREE WEEKS (from fertilization)
By the third week of pregnancy (approximately 21 days after fertilization), the heart begins to beat, pumping blood throughout the body, and the brain begins dividing into three primary sections (forebrain, midbrain, and hindbrain).
Illustrated Timeline of Prenatal Development (click below to enlarge)
Copyright ?? 2005 Nucleus Medical Art, Inc. All rights reserved. www.nucleusinc.com
FOUR WEEKS (from fertilization)
Arms and legs begin taking shape at four weeks, and the embryo is now surrounded and protected by the amniotic sac.
FIVE WEEKS (from fertilization)
Permanent kidneys appear during the fifth week, and the external portions of the ear begin to differentiate. Hands and wrists are also beginning to take shape.
SIX WEEKS (from fertilization)
By the sixth week, the brain emits waves which register on an EEG (electroencephalogram). This is the legal standard for determining if someone is alive after birth. The heartbeat can be heard with an ultrasonic stethoscope, the embryo responds reflexively to stimulus and may be able to feel pain. Bone ossification begins at this point as well.
SEVEN WEEKS (from fertilization)
Startle responses can be observed after 7 weeks, and female ovaries are now identifiable. Fingers and toes are now distinctly separated, and knee joints are present.
EIGHT WEEKS (from fertilization)
By the eighth week of pregnancy, every organ is present and in place. Ninety percent of the structures found in an adult human being can now be found in this tiny embryo which is only about an inch and a half long. The brain, at this point, makes up almost half of the embryo's total body weight, and 75% of 8-week embryos demonstrate right-hand dominance. Intermittent breathing motions (though there is no air present in the uterus) occur, the kidneys begin producing urine, and male testes are releasing testosterone. As the skin thickens, it loses much of its transparency.
Photographic Timeline of Prenatal Development (click below to enlarge)
The prenatal photographs shown above were taken by famed Swedish photograper Lennart Nilsson and are displayed here for educational, non-commercial purposes in accordance with the doctrine of "fair use".
NINE WEEKS (from fertilization)
The eyelids close at this point, and fetuses are now capable of sucking their thumb, swallowing amniotic fluid, grasping objects and responding to touch. The uterus can be recognized in female fetuses and external genitalia become more recognizable.
TEN WEEKS (from fertilization)
Fingernails, toenails and unique fingerprints all appear .
TWENTY-ONE WEEKS (from fertilization)
Viability generally begins at 21-weeks (barely 1/2 of full gestation) when a baby has a 15% chance of survival outside the womb.
3D and 4D Ultrasound of a Twenty-Four Week Fetus (click below to enlarge)
The fetus initiates labor by stimulating the adrenal cortex to secrete a hormone that induces the mother's uterus to begin contracting. It is the fetus who determines when it's time for birth.
