Prenatal Timeline

By Dorothy H

  • First Trimester: Day 2

    First Trimester: Day 2
    Zygote

  • First Trimester: Day 4

    First Trimester: Day 4
    Morula

  • First Trimester: Day 1

    First Trimester: Day 1
    Zygote
    Most health care providers will use the first day of the woman's last period as the starting point of a pregnancy. The due date is 40 weeks after the start of the woman's last period. Most women get pregnant about two weeks after their last period, so this means that they weren't actually "pregnant" during the first week or two of pregnancy.

  • First Trimester: Day 3

    First Trimester: Day 3
    Zygote
    Three days after fertilization, a typically developing embryo will contain about 6-10 cells.

  • First Trimester: Day 5

    First Trimester: Day 5
    Morula
    By the fifth or sixth day, the fertilized eggs is known as a blastocyst- a rapidly dividing ball of cells. The inner group of cells will become the embryo. The outer group will become the cells that nourish and protect it.

  • First Trimester: Day 6

    First Trimester: Day 6
    Blastocyst

  • First Trimester: 4 Weeks

    First Trimester: 4 Weeks
    • A sperm cell and egg have united and created a small ball of cells called a blastocyst.
    • The blastocyst is implanted in the lining of the uterus.
    • The placenta begins to form. It will provide oxygen and nutrients to the growing baby and removes waste from the baby's blood through the umbilical cord. GUSTATORY *Mouth begins to form tongue bud. OLFACTORY *Nasal pits present AUDITORY *First anatomical division of inner ear VISUAL *eye formation begins (day 22)

  • First Trimester: 12 Weeks

    First Trimester: 12 Weeks
    1/2 oz CR 2.5 inches
    * Fetus looks more like a human baby.
    * Toes and eyelids have formed.
    * Can clearly see the umbilical cord on ultrasound.
    * Genitals (penis or clitoris and labia) are developing.
    * Intestines are in abdomen.
    * Net week will begin to make urine and release it into the amniotic sac to make amniotic fluid.
    VISUAL
    *Precursors of rods and cones

  • Second Semester: 24 Weeks

    Second Semester: 24 Weeks
    1 1/3 lbs, 8 inches
    *Body is covered with a fine downy hair called lanugo. It keeps the protective layer of vernix on the skin.
    *Sucking reflex and may suck thumb.
    *Hair on head grows.
    *Able to swallow fluid.
    *Red, wrinkled skin.
    *Fat under the skin to keep the baby warm when born.
    *Finger/footprints begin.
    *Hiccups that may feel like small jerking.
    TACTILE
    *26 wks- primitive tactile reflexes, rooting
    AUDITORY
    *System is structurally complete, functional
    VISUAL
    *myelination of optic nerve begins

  • First Trimester: 8 Weeks

    First Trimester: 8 Weeks
    Crown to Rump length .5 inch
    * All systems and organs are in place and continue to develop.
    * Fingers begin to form.
    -TACTILE
    *Early fetal movement detected by ultrasound at 7 weeks.
    * Perioral area sensitive to stimulation 7.5 weeks.
    *Sensory nerve endings in place and functioning.
    GUSTATORY
    *mouth and tongue development complete
    OLFACTORY
    *Nasal structure and components in place
    VISUAL
    *Retinal differentiation
    *Optic nerve (wk 6-8)

  • Second Semester: 20 Weeks

    Second Semester: 20 Weeks
    11 oz. 6.3 inches
    * Halfway into the pregnancy!
    * Toenails have appeared.
    * Begins to hear.
    * Digestive system has started to work.
    * Skin is thin and delicate and is protected by a creamy protective layer called vernix.
    * Mother may feel baby's movements.
    VESTIBULAR
    *Vestibular system is functional
    GUSTATORY
    *Taste buds emerging
    VISUAL
    *All retinal layers present (22 wks)
    *Immature rods and cones (23 wks)

  • Second Trimester: 13 - 27 Weeks

    Second Trimester: 13 - 27 Weeks
    The fetus cannot live outside the mother's body during this trimester because their breathing and blood circulation systems are not sufficiently developed.
    VESTIBULAR-
    * Week 14: Sensory innervation completed

  • First Trimester: Conception through Week 12

    First Trimester: Conception through Week 12
    Conception occurs when a man's sperm meets a woman's egg. The egg becomes fertilized, moves into the uterus and implants itself onto the uterine wall. Cells begin dividing and a fetus starts to develop. However, pinpointing exactly when conception begins is hard to do because sperm can rest in a woman's body for several days after ejaculation and wait for an egg.

  • Second Trimester: 16 weeks

    Second Trimester: 16 weeks
    4 oz. CR 4.5 inches
    * Head looks large in proportion to the body.
    * Bones developing and hardening.
    * Fetal movement can be seen on ultrasound.
    * Eyes can move.
    * Baby's sex is clear.
    VESTIBULAR-
    *myelination completed

  • Third Trimester: 28-40 Weeks

    Third Trimester: 28-40 Weeks
    During these last 3 months, a baby could survive if born before full term. They would, however, need some level of special care. The baby gains weight during this time

  • Third Trimester: 30 Weeks

    Third Trimester: 30 Weeks
    3 lbs., 10.5 inches
    * Baby can kick, stretch and hands can grasp.
    * Eyes can open wide.
    * Time of fast weight gain for the baby begins.

  • Third Trimester: 38 Weeks

    Third Trimester: 38 Weeks
    6.5 lbs.
    * Toenails have reached the tips of their toes.
    * Shed most of their downy body hairs (lanugo).
    * Adding fat all over the body to keep them warm after birth.
    * Moving into position for birth and head may descend into the mother's pelvis.
    VISUAL
    *retinal vessels reach the periphery

  • Third Trimester: Full Term 40 Weeks

    Third Trimester: Full Term 40 Weeks
    7.5 lbs., 14 inches
    * Antibodies from mother are transferred to the baby providing protection against diseases.
    * At 40 weeks the baby's due date arrives.
    * Remember:
    A due date is only an estimate. Many babies are born before or after their due dates.
    Healthy babies come in many different sizes. The numbers given here are only an average.

  • Third Trimester: 32 Weeks

    Third Trimester: 32 Weeks
    3.75 lbs., 11 inches
    * The lanugo hair that protects the skin begins to fall off.
    * Toenails are visible.
    * Baby practices breathing.
    TACTILE
    * Back and legs modulate input

  • Third Trimester: 34 Weeks

    Third Trimester: 34 Weeks
    4.5 lbs., 12 inches
    * Eyes respond to light.
    * Fingernails have reached fingertips.
    * Bones are hardening but the skill stays soft and flexible.
    VISUAL
    *Iris sphincter develops

  • Third Trimester: 36 Weeks

    Third Trimester: 36 Weeks
    • Baby's skin is pink and smooth and takes up most of the amniotic sac.
    • Arms and legs have a chubby appearance. GUSTATORY
    • Week 35: Differentiation between glucose and water when calming VISUAL
    • Awake visual alertness

  • First Trimester: 6 Weeks

    First Trimester: 6 Weeks
    • Growth is very rapid in the developing embryo.
    • Eyes, ears, spine, digestive tract, and nervous system begin to develop. *Heart is beating VESTIBULAR- *Primitive semicircular canal.

  • Third Trimester: 28 Weeks

    Third Trimester: 28 Weeks
    2.25 lbs, 10 inches
    *May respond to mother's voice with movement.
    *Lungs are getting stronger. The lungs begin to produce surfactant. Surfactant is a protein that helps the lungs to expand after birth.
    *Eyes can partially open and eyelashes have formed.
    *Central nervous system can direct rhythmic breathing and control body temperature.
    GUSTATORY
    *26-28 wks, Withdrawal response to bitter taste
    VISUAL
    *Eyes open (7 mo)
    *Rapid ocular growth (28-40 wks)

  • Newborn

    Newborn
    GUSTATORY
    *(Day 3-6) Differentiate between sweet, sour, bitter, between breast milk and formula