All ages refer to time since conception. For example, 4 weeks from conception is 6 weeks of pregnancy. That is because pregnancy can be either calculated from conception, as we did, or from the first day of the last period.

The heart beat begins. /4 weeks/
Only 3 weeks and 1 day after fertilization – the heart begins to beat. Very soon thereafter, the heart motion can be seen using ultrasound technology.
By 6 weeks, the heart is pumping the embryo’s own blood to his or her brain and body. All four chambers of the heart are present and more than 1 million heartbeats have occurred.

Body has thin and transparent skin. /4 weeks/
At this point, the embryo’s skin is only one cell thick. This makes the skin thin and transparent, allowing us to see internal organs during early development.

Brainwaves can be monitored. /6 weeks/
The embryo has brainwaves by 6 weeks, 2 days! From 6 to 6½ weeks, the brain’s structures (cerebral vesicles) will double in size.

Movement Begins
. /6 weeks/
Though a pregnant woman does not feel movement till later, the embryo begins to move between 5 and 6 weeks. The embryo’s first movements are both spontaneous and reflexive. These movements are essential for the normal development of bones and joints.

Hiccupping starts. /7 weeks/
Baby hiccups in the womb are the little movements baby’s diaphragm makes when she begins to practice breathing. It begins from 7th week, but mum can’t feel them till much later.

It’s as big as a blueberry. /7 weeks/
In 7th week, the baby is 0.31 inches / 0.79 cm in long and 0.02 oz / 0.5 g in weight.

It starts to pee. /8 weeks/
The kidneys begin to produce urine, which is then released into the amniotic fluid (liquid surrounding the baby).

Fine facial hair begins to grow. /8 weeks/
Eyebrows begin to appear along with fine hairs around the mouth. Later the whole body is covered by fine hair and it will grow and shed in two or three cycles before the birth.

The baby is 90% developed. /8 weeks/
Experts estimate the 8-week embryo possesses approximately 90% of the 4,500 body parts found in adults. This means that approximately 4,000 permanent body parts are present just eight weeks after conception.

It sucks its thumb. /9 weeks/
By 9 weeks thumb sucking begins. The baby can also grasp an object, move the head forward and back and also do other body movements.

If it’s a girl, her womb is recognisable. /9 weeks/
In a female baby the womb is identifiable by 9 weeks and, within her ovary immature eggs (oogonia) can be found.

Face, palms, and soles of the feet can be sensitive to a light touch. /9 weeks/
By 9 weeks, the nerve receptors in the face, palms of the hands, and soles of the feet can sense and respond to light touch. Following a light touch on the sole of the foot, the baby will bend the hip and knee and may curl their toes.

You can recognise, if its a girl or a boy. /9 weeks/
Though gender is determined at fertilization, genitalia now distinguish male from female.
Other gender differences appear at 14 weeks, for instance, female babies exhibit mouth movement more frequently than males and this difference increases with advancing age.

Baby can swallow fluid. /9 weeks/
By 9 weeks baby may swallow amniotic fluid (with its own urine in it )

Baby can yawn. /10 weeks/
The baby yawns and often opens and closes the jaw as early as 9½ weeks.

Unique fingerprints are formed. /10 weeks/
At the ends of the fingers and toes, nails begin to emerge, as do fingerprints. These patterns can be used for identification throughout life.

The baby can pull faces. /11 weeks/
By 11 weeks, the nose and lips are completely formed. The baby can now produce complex facial expressions and, according to one group of researchers, is capable of smiling.

The baby is as big as a bigger plum./12 weeks/
At 12 weeks, the baby is about 8cm/3 inches long, which is about the same size as a bigger plum.

Bowel movements begin. /12 weeks/
Bowel movements begin as early as 12 weeks. The baby’s first poo (normally after birth) is called meconium. It is composed of digestive enzymes, proteins, hair and dead cells shed by the digestive tract.

Taste buds are developed. /12 weeks/
The taste bud cells that appeared by 7 weeks have matured into discrete taste buds, but are still scattered throughout the mouth. By birth, the taste buds will be confined to the tongue and palate or roof of the mouth.

The teeth begin to develop. /13 weeks/
The teeth begin to develop in the 13th week, but the teeth enamel begins to develop later, between 16 and 20 weeks.

Baby opens mouth if it touches it. /13 weeks/
Stimulation near the mouth evokes a turn toward the stimulus while the baby opens the mouth. This reflex mimics the rooting reflex, which persists after birth to help the newborn find his or her mother’s nipple during breastfeeding.

Mum can feel the baby movement. /14 weeks/
Although movement begins in the six week embryo, a pregnant woman first senses fetal movement between 14 and 18 weeks. Traditionally, this event has been called quickening.

Voice box is moving similarly to a crying baby. /18 weeks/
By 20 weeks the larynx or voice box begins moving in a way similar to the movement seen during crying after birth.

The whole body is covered by a white substance. /18 weeks/
Protective white substance, called vernix caseosa now encases the baby, protecting the skin from exposure to amniotic fluid and prevents it from cracking and wrinkling.

Baby girl has 7 million eggs in its ovaries.  /19 weeks/
By about 19 weeks, the number of oogonia (immature eggs) within the ovaries of a female baby peaks at approximately 7 million. From this point, not only does oogonia production end forever, but their numbers decrease to about 2 million by birth.

If the baby is born, it can survive outside of womb (with medical care). /20 weeks/
With specialized medical care some babies can survive outside the womb by 20 weeks from conception (22 weeks of pregnancy) with survival rates reported as high as 40% in some medical centres.

The baby can hear and respond to sounds. /20 weeks/
The inner ear, fully formed by 20 weeks enables hearing.
From now on, the baby will respond to a growing medley of sounds.