The common image of childbirth in a hospital involves the birthing person lying on their back, often with legs up in stirrups, a position known as the supine or lithotomy position. This posture is deeply ingrained in modern hospital practice, despite being a relatively recent development. Historically, birthing people instinctively chose upright, mobile positions like squatting, kneeling, or sitting to deliver their babies. The routine use of the supine position is often questioned by professionals and patients seeking a more natural and efficient labor experience.
Historical and Practical Rationale
The shift away from upright birthing positions began with the medicalization of childbirth in 17th-century Europe. Previously, midwives assisted most births, which occurred in vertical positions using birthing stools. The increasing involvement of male physicians led to the standardization of the recumbent position.
Lying down offered the physician better visibility and easier access to perform interventions. Tools like obstetric forceps were most effectively applied when the patient was on her back.
In the modern hospital, the supine position remains the default for practical reasons centered around provider convenience and technology. It facilitates continuous monitoring of the baby’s heart rate and allows healthcare providers predictable access for procedures, such as placing an epidural or performing an episiotomy.
Physiological Consequences of Supine Birth
Lying flat on the back during labor presents several physiological disadvantages. One significant issue is aortocaval compression, also known as supine hypotensive syndrome. In this position, the heavy pregnant uterus compresses the inferior vena cava and the aorta, major blood vessels running along the spine.
Compression of the inferior vena cava restricts blood return to the heart, leading to a drop in maternal blood pressure and reduced cardiac output. This diminished blood flow can compromise the supply of oxygenated blood to the placenta and the baby. Symptoms for the mother can include dizziness, nausea, and pallor, though some women may be asymptomatic.
Furthermore, the supine position works against the natural mechanics of the pelvis. When lying on the back, the tailbone (coccyx) is pressed against the bed, preventing it from flexing backward. This restriction can reduce the space available in the pelvic outlet by up to 20 percent, making the baby’s passage more difficult and potentially leading to a longer second stage of labor. The position also forces the birthing person to push against gravity.
Understanding Upright and Mobile Positions
Alternative positions, which involve staying upright and mobile, offer substantial physiological benefits by working with gravity and the body’s anatomy. Positions like standing, sitting, squatting, or kneeling allow gravity to assist the baby’s descent through the birth canal. This use of gravity can result in stronger, more efficient uterine contractions and may contribute to a shorter duration of the first stage of labor.
Upright postures promote greater flexibility in the sacrum and coccyx, allowing the pelvic joints to expand and create more space for the baby. Squatting, in particular, increases the diameter of the pelvic outlet, which helps optimize the baby’s alignment. These alternatives also reduce the risk of aortocaval compression, ensuring better blood flow and oxygen supply to both the mother and the baby.
Being active and able to change positions provides an instinctive form of pain management, increasing control and satisfaction with the birth experience. For those without an epidural, upright positions in the second stage of labor have been associated with a lower risk of abnormal fetal heart rate patterns and less frequent use of vacuum or forceps delivery. Even with an epidural, side-lying positions or using a peanut ball can help maintain better pelvic alignment and improve outcomes.
Advocating for Positional Flexibility
Expectant parents can proactively advocate for positional flexibility by communicating their preferences well before labor begins. This communication should be included in a written birth plan and discussed directly with the obstetrician or midwife early in the third trimester. It is important to confirm that the healthcare team is supportive of movement and alternative birthing positions, such as side-lying or hands-and-knees, provided there are no medical complications.
While movement is often encouraged, it is helpful to understand the circumstances under which the supine position may become necessary, such as during the placement of an epidural or in certain emergency situations requiring immediate intervention. Even if restricted to the bed due to monitoring or medication, the birthing person can request to be in a semi-reclined position or to use a lateral tilt, which involves placing a wedge or pillow under one hip to shift the uterus off the major blood vessels. Discussing the concept of “laboring down,” where the birthing person rests and allows contractions to move the baby without active pushing, can also help minimize time spent in a less-than-ideal pushing position.