During pregnancy, the positioning of the fetus can have a significant impact on the birthing process. Most fetuses eventually settle into the optimal head-down, face-down position, known as cephalic occiput anterior, in the last weeks of pregnancy. However, when the fetus does not assume this position for birth, it’s referred to as fetal malpresentation. One of the rarest and most challenging positions is the transverse lie, where the fetus lies horizontally across the pregnant person’s abdomen, often with one shoulder or its back facing the birth canal. This article provides information on transverse lie, its causes, effects on pregnancy and delivery, and potential interventions.
Understanding Transverse Lie: Transverse lie, also known as shoulder presentation, occurs when the fetus is positioned horizontally in the abdomen. The fetal shoulder is often located near the pelvic inlet, making vaginal delivery impossible. In some cases, the fetus may have its back or its hands and feet facing the birth canal. The likelihood of a fetus being in a transverse position at term is relatively low, around 1 in 300. However, the risk is higher before term, with a prevalence of 1 in 50 at 32 weeks of gestation.
Causes of Transverse Lie: In many cases, the specific cause or risk factors for transverse lie are unknown. However, two common risk factors for transverse lie at term are an excess of amniotic fluid (often associated with diabetes) and multiple gestation, such as twins or triplets. Other potential risk factors include previous pregnancies (multiparity), premature labor, low amniotic fluid, placenta previa (where the placenta covers the cervix), pelvic, uterine, or fetal abnormalities, which are more common in first-time pregnancies. Sometimes, the baby’s positioning may be due to underlying issues, like a short or tight umbilical cord.
Risks and Complications: Transverse lie at term can pose risks to both the pregnant person and the baby. If the water breaks while the baby is in a transverse lie position, it can lead to a potentially dangerous condition called cord prolapse, which is a medical emergency. Other complications may include obstructed labor, infection, uterine rupture, birth trauma, postpartum hemorrhage, birth defects, and stillbirth.
Effect on Pregnancy: Pregnant individuals with a fetus in the transverse lie position may experience abdominal and back pain. This discomfort arises from the stretching of the uterus in various ways and can lead to rib tightness and lung cramping. With the approval of a healthcare provider, some individuals may try deep breathing and gentle yoga exercises at home to alleviate pain and encourage the fetus to turn.
Delivery and Interventions: If the healthcare provider suspects that the fetus is in the transverse lie position at 36 weeks, an ultrasound will be performed to confirm the positioning. Since a baby in the transverse lie position cannot be delivered vaginally, healthcare providers will develop an alternative birth plan. This plan may involve an external cephalic version (ECV) procedure, aiming to turn the fetus into a head-down position for a vaginal delivery or a cesarean section (C-section).
In the case of multiple pregnancies, such as triplets, a C-section is almost always recommended. However, for twins, if the first twin is in a head-down position, the second twin may have more space to move into the optimal position. Providers may also attempt ECV or internal podalic version (IPV) if necessary, depending on the specific circumstances.
Turning a Transverse Baby: After 34 weeks, it is unlikely for a fetus in the transverse lie to spontaneously turn into a head-down position. However, in some cases, it is possible to turn a transverse baby using natural methods, provided there are no underlying health concerns. These methods may include sound or light stimulation, temperature changes, or techniques like moxibustion. Additionally, chiropractic approaches like the Webster technique and the forward leaning inversion may help encourage the fetus to move.
Intervention, such as an ECV, becomes necessary if natural methods are ineffective by 36 weeks. ECV involves a healthcare provider using their hands to apply pressure to the abdomen to attempt fetal repositioning. This procedure is conducted in a hospital to monitor the fetal heart rate and for immediate access to a C-section in case of emergency. Potential complications of ECV include placental abruption, fetal heart rate abnormalities, preterm labor, and more.
In general, the success rate for ECV in turning a transverse fetus is about 60%, which is higher than the success rate for a breech presentation. However, the decision to proceed with ECV should be based on an individual’s unique circumstances and after consultation with their healthcare provider.
If all attempts to turn the baby fail, a C-section will be scheduled to ensure the safety of both the pregnant individual and the baby. It’s crucial to communicate openly with your healthcare provider and ask any questions you may have, including those related to postpartum recovery in the case of a C-section.