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Maternal and Neonatal Outcomes Associated With Flexible Sacrum Birthing Positions

  • by Clara M. Díaz-Quintana

Introduction

In 2023, over 700 women died daily from childbirth-related causes around the world [13]. Maternal deaths during childbirth are linked to postpartum hemorrhage and infection [18]. Childbirth is a major event in a woman’s life, and having a strong understanding of different labor practices allows mothers to enter the experience better equipped to navigate their birth [1]. One often overlooked aspect of childbirth is the use of birthing positions, which play a critical role in minimizing the rate of postpartum infections and bleeding [1]. Birthing positions are categorized into 2 groups: flexible sacrum positions (FSPs) and non-flexible sacrum positions (NFSPs) [1, 2, 4, 5].  NFSPs apply pressure on a woman's sacrum,  including lithotomy and supine [1, 2, 3, 4, 21].  FSPs take weight off a woman's sacrum during labor, including sitting, squatting, leaning, kneeling, and on all fours [1, 2, 3, 4, 21]. 

FSPs increase free mobility of a woman’s coccyx by taking pressure off of her sacrum and widening her pelvic outlet. The sacrum is a wide triangular bone at the base of the vertebrae that passes weight onto the pelvis [12]. When a fetus's head descends, the coccyx, a smaller triangular bone below the sacrum, receives pressure, which straightens the sacrum and coccyx, thus widening the pelvic outlet [9]. By taking pressure off of a woman’s sacrum, FSPs increase free mobility of her coccyx, widening her pelvic outlet [1, 3, 4]. When pelvic space isn’t restricted or excessively widened, the risks of complications, such as prolonged active labor, instrumental delivery, and perineal trauma, are decreased [3, 8]. NFSPs are known for placing mothers flat on their backs and propping their feet up in stirrups when giving birth [14]. NFSPs restrict coccyx and sacral movement with the presence of a bed [3, 9]. The bones do not straighten to their full extent, hindering a mother’s pelvic outlet from widening [3, 9]. This stress can also force an excessively widened pelvic outlet, a condition known as symphysis pubis diastasis [3]. This slows labor progression, increases the rate of bleeding, and reduces the effectiveness of a mother’s contractions [9, 15]. 

During the 17th and 18th centuries, advancements in childbirth interventions, including the use of forceps, fetal heart rate monitoring, and analgesia, increasingly shaped hospital birthing practices [1, 11, 14, 15]. NFSPs became the standard birthing position so that physicians were able to gain easier access to perform vaginal examinations, monitor contractions, and utilize these medical tools, limiting women’s choice in birthing positions [14]. Yet studies show that the advantages of FSPs outweigh those of NFSPs. Mothers who labor in FSPs experience lower rates of perineal tearing and shorter active labor, and infants are more likely to receive higher APGAR scores [1, 2, 5, 8, 14 ,15, 16]. Infant APGAR scores assess newborns immediately after birth, taking note of an infant's color, heart rate, reflexes, muscle tone, and respiration [2, 17]. These outcomes are associated with decreased risk of infection and postpartum hemorrhage [1, 2, 5, 8, 14, 15, 16]. This review will focus on how FSPs promote a decrease in maternal perineal tearing and the duration of active labor, as well as their positive effect on neonatal APGAR scores.    

Impact of Flexible Sacrum Birthing Positions on Perineal Tears 

After birth, mothers are assessed for injuries, one being perineal tearing. Tearing is grouped into four degrees: 1st-degree tears involve injury to the perineal skin and vaginal mucosa, 2nd-degree tears involve injury to the perineal muscles, 3rd-degree tears involve injury to the anal sphincter complex, and 4th-degree tears involve injury to the external and internal anal sphincters as well as the anorectal mucosa [1]. Perineal tears, if not treated correctly, can lead to lifelong urinary and fecal leakage, sexual disorders, and psychological suffering for mothers [8]. 

Research shows that FSPs are associated with less severe and absent perineal tearing when compared to NFSPs [1, 2, 5, 15, 21]. FSPs decrease perineal tears because they allow a mother’s coccyx, sacrum, and pelvic outlet to move and expand freely, reducing pressure on their perineal tissues [3, 9, 12]. Badi et al. (2022) examined low-risk pregnant women who came into the hospital for labor and delivery services. Women giving birth in NFSPs had higher overall perineal tear rates than those in FSPs (20.9% vs. 11.9%), including more 2nd-degree (9% vs. 8.1%) and 3rd-degree tears (3.2% vs. 1.3%) [1]. Additionally, instrumental delivery —including the use of forceps and fetal monitors— was more common in NFSPs (10.81% vs. 6.88%) and was associated with an increased risk of perineal tears. [1]. These results aligned with those of Blomgren et al. (2025) and Shobha et al. (2025), who concluded that giving birth in FSPs significantly increased the chance of having intact perineums, while NFSPs increased the chance of perineal tears. In 2023, Familiari et al. revealed that rates of intact perineums were similar in FSPs and NFSPs, but women who gave birth in FSPs experienced fewer 1st- and 2nd-degree perineal tears. Similarly, Shobha et al. (2025) indicated that NFSPs increased rates of perineal tearing, as 7.1% of mothers had 1st- and 2nd-degree tears, whereas only 4.3% of women in FSPS experienced 1st- and 2nd-degree tears. Together, these findings show how FSPs consistently reduce the likelihood and severity of perineal tears compared to NFSPs. 

Understanding how maternal age and differences between primiparous (never given birth) and multiparous women (given birth 2+ times) affect perineal tearing is crucial for identifying factors that increase the risk during childbirth [4]. Caglioni et al. (2023) examined two groups of women, one primiparous group and the other multiparous, all of whom gave birth in a mix of FSPs and NFSPs. Evidence revealed that maternal age increased the risk of perineal tearing in both groups of women [4]. Maternal age increases the likelihood of perineal tearing because older age is associated with the reduction of elasticity in perineal tissue and longer active labor [4, 19]. Additionally, primiparous women had an increase in intact perineums in FSPs, while multiparous women had an increase in intact perineums in NFSPs [4]. Multiparous women have more elastic perineal tissue, leading to less resistance to stretching and a naturally lower risk of tears [19]. While primiparous women are more prone to perineal tears because of greater tissue resistance and a lack of prior stretching, researchers have found ways to support those who prefer to give birth in FSPs despite their higher risk of tearing [19]. Rodrigues et al. (2023) investigated strategies to support women who preferred FSPs during birth but were at higher risk of perineal tearing due to their age. Researchers observed women who came into a hospital for labor and delivery services and split them into 2 groups: one received warm perineal compresses and massages during labor, and the second did not. Both groups progressed through labor in FSPs [10]. Data revealed that the rates of intact perineums rose in women who had perineal massages and warm compresses when compared to those who did not receive extra treatment (47% vs. 26.3%) [10]. Additionally, the rates of 2nd-degree perineal tears declined in women who received warm compresses and massages (7.2% vs. 12.3%) [10]. By gently placing warm compresses onto a mother's perineum as a baby stretches through the tissue, muscle spasms decrease, thus relaxing the anal sphincter [10]. These findings highlight the value of supportive interventions, but further research is needed to determine techniques for differing ages and risk profiles. 

Figure 1. An illustration of a woman lying on her back with her legs raised, which may restrict sacral movement and limit pelvic flexibility during childbirth.
Figure 1. An illustration of a woman lying on her back with her legs raised, which may restrict sacral movement and limit pelvic flexibility during childbirth. 

Influence of Flexible Sacrum Labor Positions on Neonatal APGAR Outcomes

Intact perineums are associated with fit neonatal APGAR scores, and these outcomes are intertwined with FSPs [1, 2]. In the APGAR score, five different observations are scored 0, 1, or 2, and are recorded at both 1 and 5 minutes after birth; total scores ranging from 7–10 are considered healthy [2, 17]. In FSPs, gravity accelerates fetal descent and enables the pelvis to expand for a smoother, less stressful birth for both infant and mother [15]. Less stressful births are positively associated with higher infant APGAR scores [15]. FSPs enhance the fetus’s ability to rotate within the mother’s womb, promoting optimal positions for birth [3, 4]. FSPs help shorten labor and reduce birth-related stress for infants [15]. A few studies found no statistical difference in infant APGAR scores based on a mother’s birthing position, while other researchers concluded that the number of low infant APGAR scores decreased when mothers gave birth in FSPs [1, 14]. Caglioni et al. (2023) found no statistically significant relationship between maternal birthing positions and neonatal APGAR scores; however, physicians observed a positive correlation between FSPs and infant APGAR scores above 7. Conflicting results can be associated with the use of anesthesia during labor, gestational age, and even baby's sex since these all impact infant APGAR scores as well [4, 19]. 

Figure 2. An illustration of a woman lying flat on her back during childbirth, which may forcibly widen her pelvic outlet, restricting pelvic mobility and reducing the effects of gravity during labor.
Figure 2. An illustration of a woman lying flat on her back during childbirth, which may forcibly widen her pelvic outlet, restricting pelvic mobility and reducing the effects of gravity during labor. 

Birthing positions, in addition to intrapartum support, can impact neonatal outcomes [2, 7, 20]. In 2025, Blomgren et. al. examined intrapartum support and birthing positions as contributors to high infant APGAR scores. Intrapartum support refers to the emotional and physical support and advocacy provided to a woman throughout labor [2, 7, 20]. Researchers concluded that receiving intrapartum support while in FSPs significantly decreased labor stress and increased the number of infants with APGAR scores above 7 [2]. Higher education, maternal age, and employment did not affect women's choice of birthing positions, but those factors did affect the intrapartum support received while in labor [2]. Intrapartum support is linked to shorter labor and higher rates of spontaneous vaginal birth [2]. Combined, intrapartum support and FSPs promote a labor process with fewer medical interventions and improved infant APGAR scores [7].

Impact of Flexible Sacrum Birthing Positions on the Duration of Active Labor

Active labor begins when the mother has a fully dilated cervix and ends when the baby has completely exited her body [1]. Active labor is considered the most stressful part of birth for both mother and baby because prolonged time in this period increases the risk of postpartum hemorrhaging and infections, all of which increase with NFSPs [1, 5, 18]. During an infant's delivery, maternal birthing positions play a significant role in the descent of the fetal head; upright positions can help reduce the duration of active labor [1, 5, 6, 14, 15, 16]. Studies concluded that the duration of active labor significantly decreased when a mother used FSPs compared to NFSPs [1, 4, 5, 6, 14, 15, 16]. In 2022, Badi et al. examined two groups of pregnant women who were admitted to the hospital for birth services, comparing those who chose to deliver in FSPs vs NFSPs. The average duration of active labor was 56min (SD +/- 180 mins) for women in FSPs and 82 mins (SD +/- 24 mins) in NFSPs [1]. Familiari et al. (2023) and Shedmake et al. (2021) both concluded that reduction in fetal descent time was positively associated with FSPs in both multiparous and primiparous women in FSPs compared to NFSPs. FSPs use gravity to help amplify downward pushing by increasing the strength of contractions and fetal alignment in the birthing canal [1, 15]. Shobha et al. (2025) observed primiparous women going into labor and grouped them based on their birthing position, FSPs vs NFSPs. The average duration of active labor for women in FSPs was 25.93 minutes, compared to 32.95 minutes for women in NFSPs [15]. In NFSPs, women work against gravity when on their backs as their weight compresses their abdominal vessels, which slows blood flow to their fetus and placenta, prolonging active labor. [15]. Undergoing postural changes throughout labor decreases active labor time, increases the chance of vaginal deliveries, and decreases instrument usage when compared to those who stayed in NFSPs [16]. 

Figure 3. An illustration of a woman in a squatting birthing position, demonstrating how a flexible sacrum can help create more space in the pelvis during childbirth.
Figure 3. An illustration of a woman in a squatting birthing position, demonstrating how a flexible sacrum can help create more space in the pelvis during childbirth. A woman kneeling while leaning over a birthing ball, demonstrating a supportive position that may promote mobility during labor. A woman on their hands and knees, demonstrating a position that may help relieve back pressure and allow greater pelvic mobility during child birth. A woman laying on her side with a pillow between her legs, demonstrating a comfortable position that may promote pelvic widening during labor. 

Birthing tools are commonly used in FSPs and can help decrease the duration of active labor.  Fraga et al. (2024) explored ways to support women with peanut birthing balls. These are peanut-shaped exercise balls that help labor progression and are placed between women’s legs during labor to open their pelvis [6]. The use of a peanut ball significantly decreased the duration of active labor for women who were in FSPs when compared to those in NFSP [6]. Partnering peanut balls with FSPs increased vaginal deliveries by 11% [6]. Peanut balls are cost-effective and help increase the speed of active labor [6]. They allow mothers to change positions, opening up their pelvic outlet and promoting fetal descent for more efficient contractions [6]. 

Conclusion

This review evaluated FSPs and their ability to reduce maternal perineal tearing, shorten active labor, and positively influence neonatal APGAR scores. In addition, research found that FSPs help women feel more in control of their delivery and generally improve maternal outcomes without causing negative effects on neonatal outcomes. These findings challenge the narrative of NFSPs being best for laboring mothers, as no evidence was found of FSPs harming mothers' health. However, as studies are primarily conducted by midwives in developing countries, further research is needed to advance trials to more developed medical centers and care environments. Research supports giving women the freedom to choose their preferred birthing positions, not just those favored by physicians.

Photograph of Clara M. Díaz-Quintana.

About the Author: Clara M. Díaz-Quintana

 Clara Díaz-Quintana is a fourth-year Biological Sciences major at the University of California, Davis, pursuing a future career in women’s health. As a practicing doula, she has gained firsthand experience supporting individuals through pregnancy and childbirth, which has deepened her appreciation for the birthing process. Through this paper, she hopes to highlight the importance of patient autonomy during childbirth and advocates for allowing women to choose their birthing positions when it is safe for both mother and baby. In addition to school, she is currently assisting Dr. Nommsen-Rivers in the MOM2child study. Outside of research, she is the president of PAN’DA and a part of the C.O.N.N.E.C.T.E.D. Clinic.

Author’s Note

I wrote this piece to better understand how childbirth positions affect maternal and neonatal outcomes, and to challenge the assumption that supine positions are best for labor and delivery. This topic felt important to me because women’s health has often been shaped by institutional norms rather than by the preferences of the women themselves. By focusing on flexible sacrum positions, I wanted to explore how small shifts in practice can lead to meaningful improvements in both physical outcomes and patient autonomy. I wrote this literature review for expectant mothers and women in general to help inform people about how birthing positions can influence birth experiences. I am very passionate about medicine and women’s health. I was drawn to this topic because it highlights the connection between evidence-based care and patient empowerment. In the end, I want readers to realize that progress in medicine does not always require new technology or interventions. Allowing women to have greater control over their own bodies during one of the most vulnerable moments of their lives needs to be physicians' top priority. 

References

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