What you need to know about these examinations

Long before the pregnancy is visible, your baby can be visualised for you with the help of an ultrasound scan. It is a frequently used method for monitoring and accompanying your baby's development. For many pregnant women, these examinations are the highlight of their antenatal care, as the view of the growing life in the uterus is an exciting visual opportunity to get closer to the baby. But how do ultrasound examinations actually work, which examinations are really necessary and what considerations should you make in advance?

This article gives you an overview of everything you need to know about ultrasound examinations during pregnancy - from the basics to the individual screenings and beyond.

What is ultrasound?

Ultrasound is one of the diagnostic imaging procedures. It uses sound waves that operate at a frequency that is inaudible to the human ear. These waves are emitted by a special transducer that directs them into the body. Different tissue structures reflect these waves to different degrees - depending on their density and composition.

The returning sound is registered by the ultrasound machine and converted into an image. This creates the typical black and white ultrasound images that give you and the doctor an insight into the inside of your body.

How is ultrasound used during pregnancy?

The use of ultrasound depends on the stage of pregnancy:

• In early pregnancy:
  During the first few weeks, the uterus is still small and lies deep in the pelvis. It is therefore often necessary to vaginal ultrasound examination to be carried out. A small probe is inserted into the vagina to visualise the embryo, the uterus and any visible structures such as the yolk sac.

• From the 12th week of pregnancy:
  At this point, the uterus grows beyond the pubic bone and the ultrasound can usually be performed through the abdominal wall. To do this, a gel is applied to your abdomen to improve contact between the transducer and the skin.

Which ultrasound examinations are planned?

In Germany, the Maternity guidelines the number and scope of ultrasound examinations during pregnancy. Three examinations are planned, which are carried out as so-called screenings:

1. First trimester screening (10th-14th week of pregnancy):

   • Checking the duration of pregnancy and the embryo's stage of development.
   • First indications of possible malformations or developmental abnormalities.
   • Measurement of the crown-rump length (SSL) to determine the gestational age.

2. Second trimester screening (19th-22nd week of pregnancy):

   • Detailed examination of the baby's organs.
   • Checking growth and placental function.
   • Assessment of the amount of amniotic fluid.

3. Third trimester screening (29-32 weeks of pregnancy):

   • Monitor your baby's growth and development.
   • Assessment of the position of the baby and the placenta.
   • Checking the supply through the umbilical cord.

Additional ultrasound examinations: Why are they so common?

Many expectant mothers have significantly more ultrasound examinations than the three planned. This is because many pregnant women go to the gynaecologist very early on - usually immediately after the positive pregnancy test.

In these early weeks, however, the embryo is often not yet developed enough to detect heart activity or determine a definite pregnancy. Therefore, several check-ups are often carried out at short intervals to monitor development.

The three regular screenings

1st first trimester screening (10th-14th week of pregnancy)

The first trimester screening is often the first time you can see your baby on the screen. It is impressive how much is already visible: the head, tiny arms and legs and possibly the first movements.

Typical measurements:

• crown-rump length (SSL): Used to determine the gestational age and to check growth.
• Biparietal diameter (BPD): Measures the distance between the two sides of the skull and gives an indication of head development.

Example: At 10 weeks, the SSL is about 3 cm, the BPD is about 2 cm, and the baby's weight is about 4 g.

2nd second trimester screening (19th-22nd week of pregnancy)

This screening is often referred to as a 'major organ screening' as it involves a detailed check of your baby's organs.

Typical measurements:

• Biparietal diameter (BPD): Checks the head development.
• Femur length (FL): Measures the femur and provides information about growth.
• Abdominal circumference (AU): Assessment of the development of the internal organs.

At this point, your baby weighs around 300 g and is around 25 cm long.

3rd third trimester screening (29th-32nd week of pregnancy)

The third screening is used to check the growth and position of your baby. The placenta and the amount of amniotic fluid are also assessed.

Exciting: Many babies are already in the cephalic position at this point. However, if your baby is still in a breech position, this is not a cause for concern - it still has time to turn.

Opportunities and limitations of ultrasound diagnostics

Ultrasound is a valuable tool for checking your baby's health and development. However, not all abnormalities that are diagnosed are treatable. Some findings can cause uncertainty without providing a clear diagnosis.

It is therefore important that you think about this before every examination:

• What information would you like to know?
• How do you deal with possible findings?

Ultrasound and sex determination: What is really important?

The sex of your baby has no medical relevance and should therefore not be the main reason for an examination. Of course you can find out whether you are expecting a boy or a girl - if the sex is visible during an examination and you want to know.

Important: In Germany, you should not have additional ultrasound examinations that are only used to determine gender. This is because these examinations are not medically necessary. The Federal Office for Radiation Protection explicitly warns against the excessive or non-medically necessary use of ultrasound technology during pregnancy.

What should you look out for?

• Find out about the examinations in advance.
• Ask specifically about the possibilities and limits of diagnostics.
• Make a conscious decision about which examinations are important to you.

Use ultrasound consciously

Ultrasound examinations during pregnancy are a good way of monitoring your baby's development and, if necessary, helping the child to develop healthily by activating the appropriate medical help. At the same time, it is important to be aware of these examinations and to focus on what is important: the health of your child.

By informing yourself well in advance and being clear about your wishes and priorities, you can make the most of your prenatal care. And the most important thing remains: Your baby is unique - regardless of measurements, gender or external expectations.