First Trimester

Week 2

Periphery cells (trophoblast) expand, reaching out to gestational parent, center cells form 2 bubbles/spaces, to ecto and endo tissue layers
"Plant phase"

Week 3

Emergence of meso tissue, blood forms as an organ, connecting stalk forms and enter (from the periphery) as the middle layer, filling in and creating spaced connection between the ecto and endo layers
Massive growth
Primitive streak, midline, creates a vertical orientation on the plate of center cells, notochord forms
Heart begins to form at the top
Nervous system begins to form as the neural groove
Somites form as the beginning of the spine
"Animal phase"

Week 4

Heartbeat arises
Flexion, folding
Yolk sac is sucked in to form the gut
Organized groups of cells form the basis for most systems: vascular, nervous, muscular, digestive, skeletal
12 ro 33 pairs of somites
Neural tube closes
Cells for eyes and ears appear
Building blocks appear for 40 pairs of muscles
Head, trunk, tail, arm buds
Slow generalized movements occur in response to skin stimulation

Experiences for the gestational parent in the first month

Discovery of being pregnant, sometimes this is known as it is happening, sometimes 2 or 3 weeks later. This is also a good time to listen to music, relax, write,  notice dreams, and begin to be aware of their own birth.

Week 5

Pharyngeal arches arise, each wired with a major artery and cranial nerve, these contain apparatus for hearing, speaking, breathing, eating, and facial expressions, these are structures of the social nervous system
3 parts of the brain and all cranial and spinal nerves form, the brain is expanding rapidly
Arm and leg buds form
Heart develops chambers, the heart is huge
50% of the whole body is heart and brain
Liver, stomach, esophagus, spleen and pancreas begin to develop
Upper limbs segment forming, the shoulders, hands and wrists
Sex cells migrate from yolk sac
Head and tail nearly touch

Week 6

Face forms, the upper and lower jaw, teeth and facial muscles begin to develop
Mound erupts where external ear will grow
Eyes begin to show color, and eye muscles begin to form
Fingers and toes appear
Thalamus, hypothalamus and cerebellum form
Cartilage and bones form
Testicles and ovaries develop
Reflexes of sucking and grasping arise
Strong brisk movements emerge

Week 7

Gestational phase: fetus
Face rounds out
Semicircular canals, palate, heart valves, nerve cells and retina develop
Forebrain (understanding), midbrain (hearing) and hindbrain (seeing) are formed

Week 8

Eyes migrate to the front
Taste buds arise
Stomach is large
Brain wave activity resembles an adult
Head and trunk bend with stimulation
All major systems are formed

Experiences for the gestational parent in the second month

There is a sea or hormones, elevated estrogen and progesterone. Some people feel nausea, dizzy or tired. Many people are sensitive to emotions, with self, other and surroundings. This is also a natural time of more talking with the little one inside. It's also a time to reflect on their own childhood.

Month 3

Week 9: teeth, nails, nerves for eyes, nose and tongue and vestibular system develops, genitals differentiate, eye lids form, skeletal and muscles grow

Week 10: palate and lungs complete, gallbladder secretes bile, muscles of digestive tract develop

Week 11: taste buds and olfactory nerve develop, lungs expand and contract, thumb and forefinger oppose, kick, curl toes, frown, purse lips, individual facial expressions, sucks if lips are touched


Second Trimester

Month 4 - 2nd Trimester

Risk of miscarriage drops to 2%
Bonding increases
Heart is fully developed
Nerves are myelinated
Eyes are sensitive to light
Ears are sensitive to sound
Sucks thumb, grasps umbilical cord
Reacts to taste
Reacts to music

Month 5

Earliest oint for survival outside of the womb
Hearing apparatus complete, recognizes sound, parents' voices, perceives and remembers sounds and speech
Later will remember stories told repeatedly in the womb (there's a story of a cellist who knows music sight unseen that was played to her in utero)
Brain structures for learning and awareness are in place, cortex is almost as developed as at birth
Periods of waking and sleep, with evidence of dream sleep

Month 6

Expresses stress with kicks
Responsive to talking and touching the belly
Will calm with calming music


Third Trimester

Month 7

Remembers and prefers tastes and flavors that tasted in the womb
All responses are present
If gestational parent thinks habit smoking the baby will respond
Listens intently to stories now and after birth, a baby won't listen when a parent reads backwards (meaning, it's not just about the sound of a parents voice)

Month 8

Right and left hemispheres of the brain begin to work together