When ultrasounds are no help to you in visualizing your baby growing inside you, in your early pregnancy weeks, reading about your baby growth is the best way!
Sometimes ultrasounds give you too little
information in visualizing your baby’s week by week growth in your early
How your baby grows and changes it's shape every week is both interesting and emotional for the a mother to know. Below we've explained the week by week development of the foetus:
Week 1 – When it all
Day 1 begins with fertilization. Fertilization is
the fusion of male sperm and female ovum. The fusion results in the
creation of the very first cell of the baby called the zygote.
Division of the Baby’s
The single-celled zygote now undergoes cell
division splitting itself into two cells, then four cells and then into eight
cells. The multiple celled zygote is called morula.
Fluid then starts filling in the morula. As fluid
fills in the morula, the cells naturally divide into two halves:
Embryoblast (Grows to
become the Embryo)
Trophoblast (Grows to
become the Placenta)
By the end of the first week of pregnancy, the
baby’s cell now gets attached to the mother’s body. This process of attachment
is called implantation.
Week 2 - The baby
cells further divide
Placental circulation starts off in this week with
complete penetration of placental tissue into the uterus.
The formation of the initial layers of the baby now
starts. These layers are namely:
Epiblast (forms the
future skin and hair of the baby)
Hypoblast (forms the
future muscles of the baby)
(forms the future mouth of the baby)
Week 3 to 8 - Budding
into a Human
Organ formation of the baby starts in week 3.
The baby is medically referred to as the Embryo
from this period up till week of pregnancy. The
expected length of the baby is about 2-3 mm at the start of week 3 of pregnancy and is expected to measure up to 30 mm by the end of week 8 of pregnancy.
The three major layers of the baby namely the
Epiblast, Hypoblast and Prechordal Plate further develop during these weeks.
All organs of the baby start developing during
these weeks including the skin, eyes, ears, heart, brain and stomach etc.
Especially the baby’s upper body (arms, fingers and elbows etc.) begin to
develop and start giving a clearer shape to the baby’s body.
However, no sex determination is possible as
genitalia begin to differentiate up till week 8 of
Week 9 to 12 - Embryo turns into Feotus
Embryo is now called the fetus since it starts
forming prominent human bodily features. The expected normal length of the baby
is about 45-50 mm in week 9 of pregnancy.
Facial features of the baby start to grow and
genitals are fully formed by week 10 of pregnancy.
By the end of week 12 of pregnancy, a
normal baby is expected to grow in length to about 70-90 mm.
Week 13 to 20 - Your
All major organs grow as the baby grows. Formation
of the baby’s blood cells also takes place during these weeks.
During these weeks, the baby’s hair starts to grow
all over the body and head of the baby. It is during this period that the
mother starts to feel baby movements (also known as baby “kicks”).
Sex determination is possible by week 12 of pregnancy.
A normal baby is expected to measure about
135-140 mm by week 13 of pregnancy.
Week 21 to 28 – Viable
The baby is viable from the beginning of week 21 of pregnancy.
Being viable in pregnancy terms means that the baby can be born with reasonable
chances of survival.
Your baby is expected to measure about 220 mm at the
start of week 21 of pregnancy and is expected to reach a length of up
to 280 mm by week 28 of pregnancy.
The baby now moves its fingers, lips and feet etc.
and can open and shut its eyes. Your baby also has its own breathing lungs by
this time. Baby sucking on its thumbs can be viewed in 3D ultrasound.
Week 29 – 36 – It’s
The baby is normally expected to measure about 290
mm at the start of week 29 of pregnancy and should normally have a
length of up to 350 mm at the end of week 36 of pregnancy (i.e. the ninth month of pregnancy).
During this period, the baby’s bodily hair lessens.
However, the baby’s head hair remains thick and dark. The baby can move its
hands, feet and head, up and down.
A pregnancy is expected to deliver a healthy baby
by the end of the 9th month of pregnancy.
presentation is a general outlook of embryo inside uterus, to make you understand
the growth and shape of the baby inside you. It may vary a little bit with
every other pregnant woman depending upon their case as everyone's case is
Welcome to Babyinfo – the ultimate pregnancy and newborn information guide. We are here to help you find all the pregnancy and baby info you need to make the most beautiful experience of your life even better.
Our team is comprised of an amazing mix of experienced mothers, recently pregnant women, and editors with tremendous medical knowledge in the fields of gynaecology and childbirth.
Think of us as your friendly advisors, here to give you honest, easy to understand and authentic information. We are here to be your support at this crucial time in your life, when you need it the most.
Note: This website is in no way meant to replace doctors, hospitals, or other healthcare providers that may be utilized by current mothers or mothers-to-be. All mothers are advised to see a doctor for medical advice and the appropriate care before, during, and after pregnancy.