Human Development

When does life begin?

1. Zygote Stage (Conception to 10 days)

The new baby has his own DNA, his own genetic make-up from day one; His or her gender and blood type are present at the moment of conception (when the egg meets sperm).  “Zygote” is the name used to describe the developing baby for the first two weeks. 

This tiny new cell, smaller than a grain of salt, contains all of the genetic information for every detail of the newly created life – the color of the hair and eyes, and the skin tone.  This new baby is a unique life, separate from its mother with its own DNA, its own gender, its own growing organs.  The mother is needed for warmth, protection, and nutrition.

The baby’s heart is beating before the mother misses her first period.

The lining of the uterus prepares for implantation. Implantation, when the unborn child attaches to the uterus, generally occurs between the 6th and 12th day of life.

Please note – when a pregnant woman is hospitalized, there are always two charts at the end of her bed because the doctors know that there are two patients. Two different doctors will care for the woman – a pediatrician for the baby and an obstetrician for the woman.

It is helpful to understand that a woman’s uterus (womb) is normally a hard muscle and the cervix is soft. After a pregnancy and implantation occurs, the uterus becomes soft and flexible and the cervix becomes hard and tightly shut. The closed cervix now will protect the unborn baby from infection and will start to reopen when the amniotic fluid starts to leak, indicating the start of the journey down the birth canal. The baby is delivered, the umbilical cord is cut and then app. 15 minutes later, the woman continues to experience contractions and the placenta and umbilical cord are delivered. During the next 24 hours, contractions continue and the uterus shrinks back to the way it was before conception.

A popular argument for abortion rights is “it’s my body and I can do whatever I want.”  When a woman is pregnant, there are two bodies – the woman’s AND the unborn baby’s. Everything that came with the baby leaves with the baby.

At no time is the unborn a part of the mother’s body. She is providing only an anchorage.

2. Embryo Stage ( 2 – 8 weeks)

The fertilized cell travels out of the fallopian tube and implants onto the wall of the uterus (womb). Once implantation occurs, hormones trigger the mother’s body to sustain a pregnancy and prevent a monthly period.

Mitosis is the process of cells dividing and multiplying, which begins after the zygote stage.

Trophoblast surrounds the embryo. It is a filmy substance that will turn into the placenta and umbilical cord. The umbilical cord connects a baby with her mother via the placenta. The placenta is part of this new life and is not part of the mother. The baby receives oxygen and nourishment from the mother, through the umbilical cord.

The embryo sits in a sac of amniotic fluid.
Heartbeat, brain waves, and foundation of the entire nervous system are present.

  • At 3 weeks (19 days), doctors can hear the heartbeat with a stethoscope.
  • At 6 weeks the brain waves can be detected.
  • At 7 weeks the skeletal system is complete. Baby has a mouth with lips, an early tongue.
  • At 8 weeks the fingerprints are set. The baby is about ½” long.

Fetus is Latin for “little one.” This is what a developing baby is called from 8 weeks until birth.

At 10 weeks every organ is in place and functioning. Bones begin to calcify at this time. From this point, the baby will only grow and mature.

Tiny human feet are completely formed. The fingerprints will NEVER change for the rest of our lives.

  • At 10 weeks the baby is highly sensitive to touch (when eyelids or palms are touched, they close).
  • Baby can squint, swallow, and stick out his tongue. 
  • The baby is sensitive to light at 16 weeks.
  • The baby responds to sounds at 27 weeks.
  • The baby sleeps 90-95% of the day at 32 weeks and sometimes experiences REM sleep, an indication of dreaming.
  • 2/3 of human development takes place in the mother’s womb.

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