Preparing for childbirth
During the third trimester, the focus shifts from anatomy to function and preparation for childbirth. Key questions: does the fetal growth correspond to the term (growth retardation requires special monitoring), what is its position - cephalic, pelvic or transverse, where is the placenta located and is there a presentation, is there enough amniotic fluid, is there an entanglement of the umbilical cord. The estimated fetal weight influences the choice of delivery tactics. The study is often supplemented with Doppler blood flow in the umbilical cord arteries and uterine arteries - it shows whether the fetus receives enough oxygen and nutrients.
Why are timing screenings needed?
It is no coincidence that ultrasound examinations during pregnancy are carried out at certain times: each window shows its own signs. At 11–14 weeks, the thickness of the nuchal translucency and nasal bone are assessed - markers of chromosomal abnormalities that later disappear. At 18–22 weeks, the formation of organs allows for a detailed examination of the anatomy of the fetus. In the third trimester, the main things are growth, fetal position, condition of the placenta and blood flow.
Missing the screening window means losing information that cannot be obtained at another time.
What is being assessed
- heart rate, number of fetuses and gestational age
- fetometry - dimensions and compliance with deadlines
- anatomy of organs and identification of malformations
- localization, structure and maturity of the placenta
- amount of amniotic fluid
- blood flow in the arteries of the umbilical cord, uterus and fetal vessels
Security
Ultrasound during pregnancy has been used for more than half a century and is recognized as safe when used for medical reasons. International recommendations advise not to conduct research without indications solely for the sake of photos or videos, and also to limit the duration of exposure - the principle of reasonable sufficiency.