What changes do we see in 13 week ultrasound

early miscarriage

During the 13th week of pregnancy, we can see many changes in the baby. The baby is growing in size and his/her body parts are clearly visible. The baby’s facial features also become apparent. This is the time when a pregnant mother can hear her baby’s heartbeat on a fetal monitor for the first time. The mother may experience increased vaginal discharge which may turn clear or yellowish at times due to high estrogen levels in her.

We can see the following changes in 13 weeks.

Figures growth

In 13 weeks fingers grow more and also the color of fingers can be seen.

Outer ear

The outer ear starts growing up to its final shape, that’s why it is called a pinna ear before birth after that outer ear is called an auricle. (pinna, auricles are part of the outer layer.)

Skin growth

A screen shot of a television

We can see more skin growth in 13 weeks, also some hair growth on eyelids is seen. (secondary sex characters)


Teeth start growing and we can see that clearly in the 13th week’s ultrasound.


We can clearly see the heartbeat.


The face is more visible and facial features such as nose, mouth, eyebrows, etc. are more visible in 13-week ultrasound.

Umbilical cord

The umbilical cord is getting mature and we can see that on the 13th week’s ultrasound.

Genital organs

A woman sitting on a bed

Genital organs become mature and we can clearly see male and female genital organs on the 13th week’s ultrasound.


Lungs grow up at the rate of 1cm every month so we can clearly see some development in the lung area in the 13-week ultrasound. 

Internal reproductive system

Male and female sex hormones (androgens) begin to be produced by the testes around 11 weeks gestation. With the maturation of the Leydig cells, testosterone secretion increases, and male external genitalia begin to develop. By 13 weeks gestation, round-cell clusters (gonadal cords) that will become the testes can be seen along the edge of each mesonephric duct as it enters the cloacal membrane (the early urogenital sinus). The ovaries appear by 14 weeks as solid cellular clumps on either side of the developing uterine horns; however, these lumps disappear before 20 weeks. By the 13th week, the fetus’s head is moreover the abdomen and we can clearly see that in ultrasound.


Nails start growing in 13 weeks.


Tongue starts moving and we can see that in 13 weeks’ ultrasound.

Upper arm

The upper arm is visible and the wrist and elbow area is more visible in the 13th week. Fingertips: fingertips become red in color and fingers growth rate increases in 13 weeks’ ultrasound.


The liver grows at the rate of 1mm per day and in 13 weeks we can see some development in the liver area.


The buttock is clearly visible and we can see its shape in 13 weeks.


Legs start growing and knee caps become more visible as well as ankles.


A 13 week pregnant mother may feel that her baby has started moving actively inside her womb, which means she would be able to feel kicks for the first time from next week onwards. This active movement of the fetus is called quickening or “the first quickening”. It is


This is the overview 0f the 13-week sonography. This 13 th week is very important for a pregnant lady because it is the first time she can see her baby clearly with naked eyes. Therefore I think every pregnant lady must know about the development of her baby in different stages.

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