Transverse presentation or transverse lie describes the position of a baby in utero when it is lying sideways, horizontally across the uterus. This is opposed to the head down position many babies assume a few weeks before birth or the more complicated rear down position of a child in breech. In both cases, the baby is vertical and a vaginal birth is an option. A fetus might be in any of these positions, including transverse presentation, for months before the end of pregnancy, but at point of birth, transverse lie usually necessitates a c-section. Vaginal birth is generally thought not survivable or possible unless the fetus can be turned.
There are many potential reasons why transverse presentation may occur, though it not a very common occurrence. A pre-term birth may sometimes involve this presentation because the baby has simply not had adequate time to move into the head down position. Placental previa, where the placenta is low in the uterus, may alter the baby’s positioning and is more likely to cause transverse lie. Sometimes a malformation of the uterus, or any type of unusual dividing wall in it can restrict movement and inhibit the fetus from turning.
A multiple pregnancy is sometimes associated with greater risk of transverse presentation of the second or higher order multiple babies. Large amounts of amniotic fluid increase the risk for this condition. Having weakened abdominal muscles may also make it easier for a fetus to present in transverse lie.
Positioning of the baby or babies toward the end of pregnancy is carefully noted during prenatal examinations. If a pregnancy is near its end and a baby is in transverse presentation, doctors may attempt to turn the baby, unless there is clear indication this will not work. When preterm or regular labor occurs spontaneously, attempts might be made in the early part of labor to turn the baby too, but if these attempts are not successful, c-section delivery is very important.
There is risk to the baby’s muscular and skeletal system from transverse presentation, and in many cases, the baby simply cannot fully enter the birth canal if it is vertical. Additional risks include complications like the umbilical cord prolapsing and depriving the fetus of oxygen, long before birth would occur. With access to a qualified medical facility, these complications of a transverse lie presentation can be avoided, and most full-term babies in this position are delivered healthy via c-section. Where there is no access to medical care, the situation is perilous, mostly for the fetus. A suspected transverse presentation is best treated with sophisticated medical intervention to provide better outcomes for the mother and child.