Fetal Development

People often ask the question “When does an embryo or fetus become human?” This is an important question, as the killing of a human is murder. Fetuses and embryos actually are biologically complete individual humans from the moment of conception. However during the pregnancy fetuses develop in the human form. Development occurs much more rapidly than most people realize, and the fetus eventually gains the ability to live without its mother during the late second trimester.

  1. The first section describes The First Trimester, the first three months after conception, when an embryo first takes human form and gains human features.
  2. The Second Trimester describes the second three months after conception, when the fetus’ organs begin to function. It is during this stage that viability is reached.
  3. The Third Trimester describes the last three months of pregnancy until the birth of the child.
    Note: Abortion is still legal during the third trimester
  4. This section describes Viability, which is the state when the fetus is capable of living without his or her mother. This page talks about the importance of viability and gives information on when it occurs.
    Note: Abortion is still legal after viability

The First Trimester

Day One

Human life biologically begins at the moment of conception. This is a contested yet undeniable truth. At the moment of conception a new human is created in his or her complete form. There has never been a human with the same genetic code. There will never again be a human with the same genetic code. This “baby” only has half the genetic code of his or her mother; it is not merely a piece of her. This baby, if left under normal conditions, will grow into a human as individual as anyone alive today. This baby is already its own person.

“To accept the fact that after fertilization has taken place a new human has come into being is no longer a matter of taste or opinion … it is plain experimental evidence.” -Father of Modern Genetics” Dr. Jerome Lejeune1
“By all the criteria of modern molecular biology, life is present from the moment of conception.” – Dr. Hymie Gordon, Chairman, Department of Genetics at the Mayo Clinic1
“The exact moment of the beginning of personhood and of the human body is at the moment of conception.” – Dr. McCarthy de Mere, medical doctor and law professor, University of Tennessee1“I am no more prepared to say that these early stages represent an incomplete human being than I would be to say that the child prior to the dramatic effects of puberty … is not a human being.” – Dr. Alfred Bongiovanni, University of Pennsylvania School of Medicine1“To say that the beginning of human life cannot be determined scientifically is utterly ridiculous.” – Dr. Richard V. Jaynes1“Conception confers life and makes that life one of a kind.” -Dr. Landrum Shettles, the “Father of In Vitro Fertilization”1

The Next Three Months

After the first day, biological development into human form progresses very rapidly. Two weeks after conception, the embryo has a developing brain and rudimentary heart.3 Three weeks after conception, the baby has a working heart, the beginning of vertebrea, a closed circulatory system separate from the mother’s, developing eyes and ears and the beginning of lungs.3 Around the 25th day, lungs are fully developed, and the heart begins to beat. The heart circulates blood throughout the fetus’ body; blood completely different and often incompatible with that of the mother.2 The baby’s developed systems are already separate from those of the mother; one month after conception it is no longer a part of her.

Five weeks after conception, the embryo has developed smaller organs such as a bony jaw3, and by six weeks, it has fully developed a vertebral column , ribs3, a four-chambered heart, fingers, and nostrils2. The baby also has a developing nervous system, and brainwaves are recorded at an average of 40 days after conception.2 Death is often defined as the cessation of brainwaves, and it follows that the presence of these brainwaves guarantees the individual life of the fetus.

By 7 weeks, the baby has developed a pancreas, a bladder, kidneys, a tongue, and a larynx,2 and muscles begin to appear.3 By eight weeks, the embryo has ears, fingers, and toes, and all key bodyparts are developed or developing.3

Nine weeks into the pregnancy (about 2 months), the baby can feel pain4. In ten weeks, the baby has developing fingernails, and also begins to move by itself2. By eleven weeks the baby has the fingerprints that will identify it for the rest of its life. Twelve weeks after conception, the baby’s gender can easily be determined, it is able to swallow, and its kidneys are able to make urine2.

Fourteen weeks into pregnancy, the fetus has fully developed legs. It can kick, sleep, and move its head.

“…and so by the close of the first trimester the fetus is a sentient, moving being. We need not speculate as to the nature of his psychic attributes, but we may assert that the organization of his psychosomatic self is well under way.”
–Dr. Arnold Gesell, Yale (The Embryology of Behavior, Harper Bros., 1945)


“When doctors first began invading the sanctuary of the womb, they did not know that the unborn baby would react to pain in the same fashion as a child would. But they soon learned that he would.”- Dr. A. Liley, Prof. of Fetology, University of Aukland, New Zealand

“By 13.5 to 14 weeks, the entire body surface, except for the back and the top of the head, are sensitive to pain.” -The Development of the Brain by S. Reinis and J. Goldman

“The fetus needs to be heavily sedated. The changes in heart rate and increase in movement suggest that these stimuli are painful for the fetus.”-Valman & Pearson, “What the Fetus Feels,” British Med. Jour., Jan. 26, 1980

“. . . the hub of the needle in the woman’s belly has jerked. First to one side. Then to the other side. Once more it wiggles, is tugged, like a fishing line nibbled by a sunfish. It is the fetus that worries thus.” -R. Selzer, “What I Saw in Abortion,” Esquire, pp. 66-67

In 1984, President Ronald Reagan stated his belief that abortions are painful to the fetus. This statement received strong support from American physicians.


1. U.S. Senate Judiciary Subcommittee Hearing, April 23-24 1981
2. Ohio Department of Health
3. Gray’s Anatomy
4. National Department of Health and Human Services

The Second Trimester

By the end of the first trimester, a fetus has a beating heart, has brainwaves, moves on its own, and has many complete organs. During the second trimester organs complete their formations.

Twenty weeks after conception, babies begin to respond to small stimulations. Earlier during the pregnancy a fetus will respond to pain, however at this time the begins to respond “to a brush on its lips by sucking.”1

Twenty-three weeks (5 months) after conception, the baby is able to think. It begins to dream and is capable of learning.2 A week later, the baby learns to respond to sound. 40% of babies born at this time will reach adulthood.3

Twenty-eight weeks (6 months) after conception, the baby can breath air, and its eyes are open. By this time the fetus can hear. 90% of babies born at this time will reach adulthood.2 There is no question that the baby is now its own person, not a part of its mother. It can learn, think, and live its own life without its mother.


1. “Do You Hear What I Hear?” Newsweek Special Issue, Summer 1991
2. National Department of Health and Human Services
3. Ohio Department of Health

The Third Trimester

By the beginning of the third trimester, a fetus is completely developed, and almost every baby born at any part of the third trimester will live until adulthood. The third trimester is primarily a time for the unborn child to grow in safety within its mother. The baby is fully capable of reacting, feeling pain, and thinking. The final major developmental occurs at thirty-two weeks when fetuses gain the muscle control to firmly grasp objects.1

There is essentially no difference between an unborn third-trimester baby and a born premature baby. Each has the potential and the overwhelming probability to become an individual adult. Each has the genetic code, physical form, fingerprints, etc. that make us unique. Each has the sentient thoughts that make us human. Each can feel pain if it is killed.2

About 39 weeks after the pregnancy begins, most babies are born. After delivery is complete, babies are for the first time granted legal protection from murder. Until the completion of birth, these babies can be and are legally killed through abortion.


1. National Department of Health and Human Services
2. Previous references. See First Trimester and Second Trimester development.


A fetus is defined as being viable if it has the ability to “potentially able to live outside the mother’s womb [that is, can survive], albeit with artificial help.” The most common argument in support of legalized abortion is that a fetus is purely a piece of the mother. However it is absurd to think that this is true if the fetus is not only individual but also can live without his or her mother.

In the fifties viability was reached about thirty weeks after conception. Modern medical technology changed that to twenty-five weeks in the seventies. Now viability continues to be pushed further and further back in the pregnancy and is now as early as nineteen weeks. Here are some examples of viable children: fetuses said to be only parts of their mothers who lived and grew into individual happy healthy people without their mothers:

  • Marcus Richardson – 19 weeks, 6 days – 780 gm – Jan. ’72 – (University Hosp., Cincinnati)
  • Melissa Cameron – 20 weeks – 450 gm – Dec. ’83 – (Sault Ste. Marie Hosp., Cincinnati Enquirer)
  • Kenya King – 21 weeks – 510 gm – June ’85 – (Med. World News, Nov. 11, 1985, p. 119)
  • Suzanne South – 21 weeks, 2 days – 644 gm – July ’71 -(Bethesda Hosp., Cincinnati)
  • Kelly Thorman – 21 weeks – 596 gm – March ’71 – (St. Vincent Hosp., Toledo)
  • Melissa Murray – 22 weeks – 510 gm – June ’83 – (Victoria, Texas – Houston Post)
  • Tracy LaBranch – 22 weeks, 1 day – 538 gm – March ’72 – (Battle Creek Enquirer)
  • Ernestine Hudgins – 22 weeks – 484 gm – Feb. ’83 – (San Diego, Washington Post)
  • Mimi Faulkner – 23 weeks – 484 gm – Nov. ’78 – (San Diego, Boston Herald)
  • Tascha Hudson – 23 weeks – 580 gm – March ’74 – (Brooke Army Hosp.)
  • Simmonne Jayette – 23 weeks – 595 gm – April ’78 – (Montreal Jewish General Hospital)
  • Alicia Ponce – 24 weeks – 644 gm – April ’74 – (Associated Press)

Twenty-one and twenty-two week premature babies are now supported routinely, and have a good chance of survival. By twenty-four weeks after conception, premature babies have a 40% chance of reaching adulthood without any major complications.2 By twenty-eight weeks, the chance is 90%.3 By twenty-nine weeks, survival is almost definite. (Note: These percentages are from reports written during the late 1980s. Current survival rates are most likely much higher.)

“An inquiry in your authors’ city revealed two preemies in one hospital, both
born at 24 weeks, weighing 580 gm and 608 gm at birth. Both progressed normally and
survived without apparent abnormalities.”
– H. Falciglia, Prof. of Pediatrics, University of Cinn. College of Med.

About thirty-nine weeks after conception, the baby is born. Twenty weeks have elapsed since the baby first became viable and first gained the ability to live without its mother. Yet now for the first time it gains the legal right to life.

More Information:

Viability, Survivability, and Fetal Pain


1. Roe vs. Wade, U.S. Supreme Court, 1973, p. 45
2. Ohio Department of Health
3. National Department of Health and Human Services