Life in the Womb

Some of the most powerful pieces of information regarding abortion we can share are the details of the development of human life in the womb.

In this section, use of the word “baby” has been avoided, because this word presupposes the very thing we’re trying to show — the humanity of the preborn — and we don’t want anyone to tune out the information we’re trying to share.

Of course, there may be times when you’re talking to someone who will respond positively to hearing about “the baby’s heartbeat”; in such a case, you should feel free to modify your language.

Please note that embryonic and fetal development is presented here by referring to days or weeks after conception. This may be different from the less precise “weeks of pregnancy” typically used by obstetricians, which are calculated from the mother’s last menstrual period (LMP). Weeks of pregnancy may be more or less accurate depending on how long the woman’s cycles are and whether she has regular or irregular menstrual cycles. 

When does life begin?

Biology is clear that at conception, also known as fertilization, a unique organism comes into existence. In fact, calling the new human being a “fertilized egg” is not scientifically correct. Once fertilization begins, the unity of the sperm and egg now causes an altogether genetically different thing from either the sperm or the egg on its own. This new human being is called a zygote, not an egg at all. Since this new life possesses human DNA, is genetically separate from its mother, and is the offspring of human parents, it can only legitimately be described as a human being. 

Since there is no question that human zygotes, embryos and fetuses are alive, some have attempted to claim that human beings are not “persons” until some threshold is crossed, such as viability, the capacity to feel pain, birth, or even after birth up until the first year after birth. Such notions are not based on science but rather on ideology, philosophy, or belief. 

As far as observable science is concerned, human life begins at conception.

Source: Condic, Maureen, MD. When Does Human Life Begin? A Scientific Perspective. The Westchester Institute for Ethics and the Human Person.

What happens at conception?

At conception, a male sperm unites with a female ovum (egg). The single-celled human organism formed by the fusion of sperm and egg is known as a zygote.
Source: Condic, Maureen, MD. When Does Human Life Begin? A Scientific Perspective. The Westchester Institute for Ethics and the Human Person.

What is the difference between “fertilization” and “implantation?”

Fertilization, also known as conception, is described above, and occurs in the mother’s Fallopian tube. Implantation, which occurs 8 to 10 days after fertilization, refers to the point at which the new human being (now scientifically referred to as an “embryo”) implants in the mother’s uterus and begins to draw nourishment.

Source: Willke, John, MD and Barbara Willke. 2003. Abortion: Questions & Answers. Cincinnati: Hayes Publishing Company.

What are the various stages of development in the womb?

Many stages of prenatal development can be identified, especially in the early days and weeks of life when change takes place at an extremely rapid pace. The following are the primary stages:
  • Zygote—A single-celled human being from fertilization until the first cell division, around two weeks later
  • Embryo—A human being from the time of the first cell division until approximately the eighth week of life
  • Fetus—A human being from approximately the eighth week of life up until birth
To this list of stages of human development might be added: newborn, infant, toddler, child, adolescent, adult and senior—the continuum of human life which begins with conception.  Prenatal development and pregnancy can also be divided into trimesters:
  • First Trimester—From conception to approximately 12 weeks gestation
  • Second Trimester—From approximately 13 through 26 weeks gestation
  • Third Trimester—From approximately 27 weeks gestation to birth

When does an Embryo’s Heart Begin to Beat?

An embryo’s heart begins to beat between 18-24 days after conception.
Source: Clowes, Brian, PhD. 2001. The Facts of Life. Front Royal: Human Life International.

When can an embryo’s brain waves be detected?

An embryo’s brain waves can be detected six weeks after conception.

When do a Fetus’ Fingernails Begin to Form?

By nine weeks after conception, a fetus’ fingernails are forming. A particularly poignant scene from the 2007 hit indie film Juno cites this fact. 

When can a Fetus Feel Pain?

In the last 10 years, some pro-life legislation has aimed at banning abortion after fetuses are able to feel pain, or at requiring abortion providers to give anesthesia to the fetus before the abortion. Pro-choice advocates cite a 2005 study suggesting that fetuses do not feel pain until late in the second trimester or even early in the third trimester, far later than the vast majority of abortions are done. A lengthy list of resources making the case for fetuses feeling pain much, much earlier in pregnancy is here
In short, based on the development of the nervous system, a fetus could potentially feel pain as early as 8 weeks after conception. Furthermore, it’s common for fetuses undergoing surgery in the womb, some as early as eighteen weeks, to receive anesthesia. Ability to perceive pain is obviously assumed in those preborn patients. 
Source: Clowes, Brian, PhD. 2001. The Facts of Life. Front Royal: Human Life International.

What are Some of the Other Milestones of Fetal Development?

Other important milestones of fetal development include:
  • At nine weeks after conception, a fetus is able to bend its fingers around an object in its hand, and sucks its thumb.
  • At 11 weeks, a fetus is breathing amniotic fluid steadily and will do so until birth.
  • At 12 weeks, a fetus can kick, turn over, make a fist, open its mouth and press its lips together.
  • At 13 weeks, a fetus’ sense are present.
  • At 20 weeks, a fetus can be startled by a loud external noise.
  • At 23 weeks, a fetus can demonstrate rapid eye movements (REM).
  • At six months, fine hair grows on the fetus’ head and eyebrows, and small eyelashes begin to appear.
  • At seven months, a fetus’ hands can support his entire weight.
  • At eight months, a fetus weighs more than four pounds.
  • During the ninth month from conception, a fetus gains half a pound per week. Of the 45 total generations of cell replication that will occur by mature adulthood, 41 have already taken place.
Source: Clowes, Brian, PhD. 2001. The Facts of Life. Front Royal: Human Life International.