The 20-week anatomy scan offers a detailed look at the developing fetus and confirms its current position. When the scan reveals a breech presentation, meaning the baby is positioned with its bottom or feet facing down toward the cervix, it can cause worry for expectant parents. While breech is not the preferred orientation for delivery, finding this presentation at the halfway point of pregnancy is a common and usually temporary finding.
Why Position is Not a Concern at 20 Weeks
A breech position at the 20-week mark is considered a normal finding, as the fetus has not yet settled into its final orientation. At this mid-pregnancy stage, the fetus is relatively small, weighing about 11 ounces and measuring around 6.3 inches. This small size, combined with the generous space and high volume of amniotic fluid within the uterus, allows the fetus to move freely and change position frequently.
Fetal presentation is highly fluid at this stage, and the current orientation is not a reliable predictor of the baby’s position later in the third trimester. Before 28 weeks of gestation, the prevalence of breech presentation is high, occurring in approximately 20 to 25.7% of pregnancies. The vast majority of these fetuses will spontaneously turn head-down as the pregnancy progresses.
The Timeline for Fetal Turning
The fetus begins to move toward a more consistent vertical lie closer to the start of the third trimester. Between 28 and 30 weeks, many fetuses that were previously breech will spontaneously flip into the head-down, or cephalic, position. The percentage of babies in a breech position drops noticeably as the weeks advance, with about 7 to 15% remaining breech at 32 weeks.
The turning is influenced by the baby’s continuous growth relative to the changing shape of the uterus. As the fetus grows, the uterus generally makes the head-down position the most space-efficient arrangement. By 36 weeks of gestation, the baby has typically settled into its final position, and only about 3 to 4% of pregnancies will have a breech presentation remaining at term. This 36-week mark is when a breech position becomes clinically relevant and requires further planning.
Monitoring and Next Steps
If the fetus remains in a breech position as the pregnancy enters the third trimester, healthcare providers will begin routine monitoring at prenatal appointments. This monitoring often involves abdominal palpation, known as Leopold’s maneuvers, to feel for the location of the fetal head, back, and bottom. If breech is suspected after the typical turning window (around 32 to 36 weeks), an ultrasound scan is scheduled to confirm the exact presentation.
The follow-up scan assesses factors such as the type of breech, the location of the placenta, and the volume of amniotic fluid, all of which influence the likelihood of a spontaneous turn. Should the baby remain breech at 37 weeks, the medical team will discuss two main options for delivery. One option is an External Cephalic Version (ECV), where a provider attempts to manually turn the baby by applying firm pressure to the abdomen. If the baby cannot be turned or if the procedure is not appropriate, the standard recommendation is often a planned Cesarean section.