Complications of shoulder dystocia

Dajani, Nafisa K.; Magann, Everett F.

doi:10.1053/j.semperi.2014.04.005

Cited by 41 publications

(33 citation statements)

References 22 publications

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“…The shoulders of the human infant lack that degree of flexibility, however, and may actually provide more obstruction to the birth process than the head and the rest of the body. If the rigid shoulders get stuck in the birth canal (shoulder dystocia), serious complications can result for both mother and infant, including fetal brachial plexus injury, fractures of the fetal humerus and clavicle and postpartum haemorrhage, uterine rupture and severe perineal lacerations for the mother [16]. Shoulder dystocia is more common with gestational diabetes, the lithotomy position for delivery and other phenomena of modern life and medical intervention [17], but it should not be discounted as a factor in the evolution of close correspondence between neonatal size and maternal pelvis size and shape.…”

Section: Human Birth: Anatomy Evolutionary History and Modern Conseqmentioning

confidence: 99%

Primate pelvic anatomy and implications for birth

Trevathan

2015

Phil. Trans. R. Soc. B

100

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The pelvis performs two major functions for terrestrial mammals. It provides somewhat rigid support for muscles engaged in locomotion and, for females, it serves as the birth canal. The result for many species, and especially for encephalized primates, is an 'obstetric dilemma' whereby the neonate often has to negotiate a tight squeeze in order to be born. On top of what was probably a baseline of challenging birth, locomotor changes in the evolution of bipedalism in the human lineage resulted in an even more complex birth process. Negotiation of the bipedal pelvis requires a series of rotations, the end of which has the infant emerging from the birth canal facing the opposite direction from the mother. This pattern, strikingly different from what is typically seen in monkeys and apes, places a premium on having assistance at delivery. Recently reported observations of births in monkeys and apes are used to compare the process in human and nonhuman primates, highlighting similarities and differences. These include presentation (face, occiput anterior or posterior), internal and external rotation, use of the hands by mothers and infants, reliance on assistance, and the developmental state of the neonate.

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Section: Human Birth: Anatomy Evolutionary History and Modern Conseqmentioning

confidence: 99%

Primate pelvic anatomy and implications for birth

Trevathan

2015

Phil. Trans. R. Soc. B

100

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“…Problems associated with gestation and parturition are not uncommon in mammals (e.g., Aksel and Abee, 1983; Sheldon et al, 2006), but humans may experience particularly difficult pregnancies and births (Rosenberg and Trevathan, 2002). For example, since the human maternal pelvic outlet is smaller than the neonatal head, there is substantial risk of trauma to uterine and vaginal walls, which increases the likelihood of microbial infection (Rosenberg and Trevathan, 2002; Chaim and Burstein, 2003; Dajani and Magann, 2014). Thus, lactobacilli and low vaginal pH may serve a protective function during human birth, and these traits are unnecessary in mammals with less risky pregnancies and birth (Stumpf et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Lactobacilli Dominance and Vaginal pH: Why Is the Human Vaginal Microbiome Unique?

et al. 2016

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The human vaginal microbiome is dominated by bacteria from the genus Lactobacillus, which create an acidic environment thought to protect women against sexually transmitted pathogens and opportunistic infections. Strikingly, lactobacilli dominance appears to be unique to humans; while the relative abundance of lactobacilli in the human vagina is typically >70%, in other mammals lactobacilli rarely comprise more than 1% of vaginal microbiota. Several hypotheses have been proposed to explain humans' unique vaginal microbiota, including humans' distinct reproductive physiology, high risk of STDs, and high risk of microbial complications linked to pregnancy and birth. Here, we test these hypotheses using comparative data on vaginal pH and the relative abundance of lactobacilli in 26 mammalian species and 50 studies (N = 21 mammals for pH and 14 mammals for lactobacilli relative abundance). We found that non-human mammals, like humans, exhibit the lowest vaginal pH during the period of highest estrogen. However, the vaginal pH of non-human mammals is never as low as is typical for humans (median vaginal pH in humans = 4.5; range of pH across all 21 non-human mammals = 5.4–7.8). Contrary to disease and obstetric risk hypotheses, we found no significant relationship between vaginal pH or lactobacilli relative abundance and multiple metrics of STD or birth injury risk (P-values ranged from 0.13 to 0.99). Given the lack of evidence for these hypotheses, we discuss two alternative explanations: the common function hypothesis and a novel hypothesis related to the diet of agricultural humans. Specifically, with regard to diet we propose that high levels of starch in human diets have led to increased levels of glycogen in the vaginal tract, which, in turn, promotes the proliferation of lactobacilli. If true, human diet may have paved the way for a novel, protective microbiome in human vaginal tracts. Overall, our results highlight the need for continuing research on non-human vaginal microbial communities and the importance of investigating both the physiological mechanisms and the broad evolutionary processes underlying human lactobacilli dominance.

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“…Rates of shoulder dystocia reported in the literature vary widely, with estimates ranging from 0.1 to 2.4% of all births . It can cause serious complications for both mother and infant . Maternal complications include postpartum haemorrhage and third‐ or fourth‐degree perineal trauma, among others .…”

Section: Introductionmentioning

confidence: 99%

“…2 It can cause serious complications for both mother and infant. [3][4][5] Maternal complications include postpartum haemorrhage and third-or fourth-degree perineal trauma, among others. 5,6 Complications for the infant include brachial plexus injury and fractures, most commonly of the clavicle and humerus.…”

Section: Introductionmentioning

confidence: 99%