Malposition is a medical term meaning something in the body is in an abnormal position. It most commonly refers to the position of a baby during labor, but doctors also use it to describe a displaced IUD, misaligned teeth, or an eyelid that has turned inward or outward. The word applies across many areas of medicine, and the specific meaning depends on context. Here’s what malposition looks like in the situations you’re most likely to encounter it.
Fetal Malposition During Labor
This is the most common use of the term. During a normal delivery, the ideal position is for the baby to be head-down with the back of its skull facing the mother’s belly. Doctors call this the occipito-anterior (OA) position, and it allows the narrowest part of the baby’s head to lead the way through the pelvis.
Fetal malposition means the baby is head-down but facing the wrong direction. The two main types are:
- Occipito-posterior (OP): The back of the baby’s head faces the mother’s spine. This is sometimes called “sunny-side up.”
- Occipito-transverse (OT): The back of the baby’s head faces sideways in the pelvis.
In both cases, the baby’s head tends to be less tucked, which means a wider part of the skull pushes against the pelvis. Persistent OP position is the most common malposition, occurring in roughly 2% to 13% of deliveries. Many babies rotate on their own during labor, but those that don’t can cause significant complications.
How Malposition Affects Labor
A baby in the OP position makes labor longer and harder. In first-time mothers with spontaneous labor, the active phase averaged about 575 minutes with a posterior baby compared to 449 minutes with a properly positioned one, a difference of more than two hours. That gap held true regardless of whether the mother received an epidural or labor-stimulating medication.
The need for medical intervention also rises sharply. Among first-time mothers in spontaneous labor, 30.4% of those with OP babies required a cesarean section compared to just 6.3% with OA babies. Rates of assisted vaginal delivery (using vacuum or forceps) were similarly elevated: 36.6% for OP versus 20.4% for OA. These patterns held across different groups of mothers, including those who had given birth before, though the overall complication rates were lower for experienced mothers.
When a baby stays in a posterior position, one option is manual rotation, where the provider uses their hand to turn the baby’s head into a more favorable position during the second stage of labor. A study of 349 births where manual rotation was successful found complication rates comparable to other methods of assisted delivery: 1.7% experienced significant tearing, 4.9% had shoulder dystocia, and only 0.3% of babies had a low Apgar score at five minutes. Management decisions are typically individualized based on how labor is progressing and the mother’s anatomy.
IUD Malposition
Malposition also describes an intrauterine device (IUD) that has shifted from its correct placement at the top of the uterus. Early studies defined displacement as the IUD sitting more than 3 millimeters away from the uterine fundus (the top of the uterus) on ultrasound. A malpositioned IUD is more often associated with pain and heavier bleeding, though some people have no symptoms at all. The first clinical clue is usually a change in the retrieval strings: they may feel shorter, longer, or disappear entirely during a pelvic exam.
Several factors increase the risk of an IUD shifting or being expelled entirely. People diagnosed with heavy menstrual bleeding have roughly 2.8 times the risk of expulsion compared to those without that diagnosis, and those with a long history of heavy periods face the highest 5-year expulsion rate at nearly 14%. IUD insertion in the postpartum period also carries a slightly elevated risk of uterine perforation, particularly within 36 weeks of delivery. Breastfeeding at the time of insertion was linked to a higher perforation risk but, interestingly, a lower risk of expulsion.
Eyelid Malposition
When applied to the eyes, malposition refers to an eyelid that no longer sits in its normal orientation against the eyeball. The two main types are entropion, where the eyelid turns inward, and ectropion, where it turns outward.
Entropion is the more uncomfortable of the two because when the lid rolls inward, the eyelashes scrape against the surface of the eye. This constant irritation can cause redness, tearing, and damage to the cornea over time. The most common cause is simply aging. As the tendons and muscles that hold the eyelid taut weaken over the years, the lid loses its structural support and begins to roll. The lower eyelid is affected far more often than the upper. Entropion can also develop suddenly after an eye infection or inflammation, when the muscles around the eye spasm and pull the lid inward. Scarring from previous surgery or chronic inflammatory conditions can also cause it by tightening the tissue on the inner surface of the lid.
Dental Malposition
In dentistry, malposition refers to teeth that are out of their normal alignment, and it overlaps heavily with the term “malocclusion,” which describes how the upper and lower teeth fit together when you bite down. The standard classification system breaks malocclusion into three groups:
- Class I: The jaw aligns properly, but the upper teeth slightly overlap the lower teeth.
- Class II: The upper teeth stick out significantly beyond the lower teeth, typically because the lower jaw is underdeveloped.
- Class III: The lower teeth extend past the upper teeth, often due to an overdeveloped lower jaw.
Most people with dental malposition notice it through crowding, gaps, difficulty chewing, or jaw pain. Treatment usually involves braces or clear aligners, and in more severe cases, jaw surgery.
Breast Implant Malposition
After breast augmentation, an implant can shift from its intended pocket. Two specific types have their own names. Bottoming out occurs when the implant drops below the natural breast crease, leaving the upper part of the breast looking deflated and pushing the nipple higher than it should be. Symmastia happens when one or both implants drift too close to the center of the chest, creating a connected appearance across the cleavage area where the skin tents between the two breasts. The nipples may also point outward. Both conditions typically require revision surgery to reposition the implant and reinforce the tissue pocket.