As your due date approaches (usually by about 36 weeks), baby should naturally shift into a head-down position in your uterus to prepare for delivery. But in 3 to 4 percent of full-term pregnancies this doesn't happen and baby is left in "breech presentation." This means he or she is positioned right-side up (in terms of giving birth, that’s upside down!), with buttocks and/or feet positioned to come out first.
Breech babies can be in three diffrent positions: the frank position (buttocks pointed toward the uterine opening with legs straight and feet near head), the footling position (one or both feet pointing down), or the complete breech position (settled cross-legged, with buttocks near the uterine opening).
There’s a few ways your OB can determine whether baby is breech. One option is a physical exam. By feeling your abdomen, your doctor should be able to determine the location of baby’s head, back and buttocks. An ultrasound also may be used to confirm baby’s position. But, since baby can continue to turn right up until delivery, your doctor may not know for sure until labor begins. If baby is breech your doctor might attempt to do something called "version" which you can read about here.
So why are some babies breech? Consider baby, almost the size of a newborn. Now consider the size of your uterus. A little cramped, no? The basic explanation is that since it's tight quarters baby gets stuck. Here are some other factors that contribute to breech presentation:
[ ] Too much or too little amniotic fluid
[ ] Second (or further subsequent) pregnancy
[ ] Multiples
[ ] Abnormally shaped uterus and/or uterine growths (like fibroids)
[ ] Placenta previa (when the placenta covers some or all of the uterus’ opening)
[ ] Preterm birth
[ ] Birth defects