Trimester
Traditionally subdivided into 3 months.
Prenatal development
Last approximately 9 calendar months or 10 lunar months ( 1 lunar month consist of 28 days)
01
Week 1-2: Ovulation
✓The mother's body
prepares for pregnancy.
End of week 2: Conception
✓The sperm meets the
egg
✓Genetic material from the
mother and father combines
forming a zygote/embryo.
Week 3:
✓The zygote turns
into blastocyst
Week 4: Implantation
✓The blastocyst is
implanted in the
uterine wall
(endometrium).
Week 5-10: Embryonic period
✓Major organs starts to
grow such as the Brain,
spinal cord and heart.
✓Heart starts beating.
✓The placenta and
umbilical cord provides
life support for the
embryo.
End of week 10:
✓Bones and muscles
started to grow beneath
thin transparent skin.
Fetus
Week 11-13: End of 1st trimester
✓Arms and legs starts to
grow.
✓Fingers and toes
finished developing.
1st trimester changes/symptoms from the mother:
✓Changes felt are due to changing levels of hormones in the body.
02
Week 14:
Head
✓Fetus is 3 inches long
from head to rump.
Rump
✓Eyelids are closed
and sex organs begins
to form.
Week 16:
✓Fetus is now 5 inches
long.
✓Fine hair starts to grow
and the baby begins to do
sucking motion.
Head
Week 20:
✓The baby can now hear
and swallow.
✓Mothers will feel
flattering movement at
their lower belly as sign of
the baby being more
active.
Week 24:
✓Lungs are formed but
aren't ready to work
outside the uterus.
✓Heartbeat can be heard
by a stethoscope.
Week 28: End of 2nd trimester
✓Baby has gained more
weight and is now 12
inches long.
✓Mothers may feel better
than during the 1st
trimester.
2nd trimester changes/symptoms from the mother:
03
Week 32:
✓The baby's weight
increases rapidly.
✓Baby's eyes can now
sense light and their
eyelids open and closes.
✓Baby's bones are still
soft but are fully formed.
✓Baby may kick and jab
forcefully.
Week 36:
✓Bones have started to
harden but...
✓Bones of the skull and
the connections between
them stays soft allowing
easier passage through
the birth canal.
✓Baby turns to head
down position to prepare
for birth.
Week 37-40: End of 3rd trimester
✓All organs are ready to
function on their own.
✓Baby drops lower to
the mother's pelvis and
could be born any day
now.
✓Mother's may feel more
uncomfortable during the
3rd trimester as growing
baby puts more pressure
on their organs.
3rd trimester changes from the mother: