You may have already had a previous ultrasound to confirm the pregnancy, but if not, the first ultrasound of your pregnancy will be the 12 week ultrasound, or the first trimester ultrasound, which is performed at approximately this point in time. gestation, between week 10 and week 14 of gestation.
It is a very important test as it provides the first relevant medical information about the pregnancy. It is usually performed abdominally, although the doctor may also consider performing it or complementing it with a transvaginal ultrasound.
What is seen on the 12-week ultrasound
- Gestational age : based on the measurements of the embryo, it can be determined if the gestation time that we have calculated according to the LMP (date of the last menstruation) corresponds to the size of the baby.
- Anatomy of the baby : although it is still very small (approximately between 4 and 10 centimeters), the anatomy of the baby can already be seen. You can distinguish the head -much larger in relation to the rest of the body-, the thorax and the abdominal cavity -with the heart beating-, and the four extremities.
- Vitality of the baby or babies: the number of embryos, their movements, their heartbeat, their implantation and development within the uterus is observed.
- Major fetal abnormalities : birth defects may be seen in combination with other prenatal tests for first trimester chromosome screening or triple screening.
- Risk of pre-eclampsia and delayed fetal growth: through Doppler ultrasound, the function of the uterine arteries can be observed and thus detect a possible risk of pre-eclampsia in the mother or risk that the baby is not growing as it should.
Can you know the sex of the baby? It is unlikely that the sex of the baby can be seen so early, however if the gestation is more advanced, around week 14, it can be seen through ultrasound if the baby’s posture allows it. It is at the next ultrasound, at the 20th week ultrasound, when it can almost certainly be confirmed whether you are expecting a boy or a girl.
Triple screening and measurement of nuchal translucency
During the 12 week ultrasound, the nuchal translucency (TN) measurement is performed, an ultrasound analysis in which the nuchal fold of the fetus is measured. Nuchal translucency is the accumulation of fluid in the nape and back of the fetus’ neck , under the skin. All babies have some fluid in the back of the neck, but fetuses with an extra chromosome have more fluid in the so-called “nuchal crease.”
This measurement is crossed with the data from the triple screening test, also called triple test or prenatal screening. It is a screening or tracing test that is performed by analyzing three biochemical markers present in the mother’s blood to detect possible chromosomal alterations of the fetus (such as trisomy 21 -Down’s syndrome- and trisomy 18 -Edwards syndrome-, for example).
More on ultrasound scans in pregnancy:
- 20 Week Ultrasound: What to Look For and Why It Matters in Pregnancy
- Third trimester ultrasound: when is it done and what is observed
- Ultrasounds in pregnancy: ultrasounds in each trimester
- 4D ultrasound in pregnancy: what is it and when is it best to do it?
- 5D ultrasound in pregnancy: what is it and when to do it
In Babies and more | Triple screening in pregnancy: how to interpret the values, Pregnancy tests: detection of chromosomal abnormalities
