A large head circumference is more strongly associated with unplanned cesarean or instrumental delivery and neonatal complications than high birthweight

Abstract

A large HC is more strongly associated with unplanned cesarean and instrumental delivery than high BW. Prospective studies are needed to test fetal HC as a predictive parameter for prelabor counseling of women with "big babies."

Cliff-edge model predicts intergenerational predisposition to dystocia and Caesarean delivery

“…Medical data document higher survival rates for larger neonates ( 5 , 6 ) and lower rates of pelvic floor disorders in women with narrower pelvises ( 7 , 8 ), and thus an increase in reproductive success (i.e., evolutionary fitness) with . This directional selection toward larger is counterbalanced by obstetric selection: If neonatal size exceeds the size of the birth canal ( ), fitness drops sharply in the absence of medical care ( 9 – 13 ). For an approximately symmetrically distributed phenotype , the balance between these selective forces at the evolutionary stable state entails a constant rate of FPD ( Fig.…”

Fetal head circumference and subpubic angle are independent risk factors for unplanned cesarean and operative delivery

“…UOD is associated with significant maternal and perinatal mortality and morbidity . Operative vaginal delivery has been reported to carry an increased risk of maternal perineal traumas, urinary and anal sphincter injuries, neonatal scalp lacerations, cephalohematoma and intracranial hemorrhage, whereas emergency CS in the second stage of labor is associated with a higher likelihood of severe maternal hemorrhage, length of in‐hospital stay and admissions to neonatal intensive care unit .…”

“…More recently, several studies have shown that ultrasound assessment of HC may be useful in anticipating the outcome of labor. Vei Ooi et al showed that HC was independently associated with the need for operative delivery and Lipschuetz et al reported that this association preponderated birthweight and other maternal characteristics.…”

“…Ultrasound assessment of fetal head circumference (HC) at term has been recently suggested to reliably predict operative delivery ; likewise, a narrow subpubic angle (SPA), measured at either two‐ (2D) or three‐dimensional (3D) ultrasound, has been shown to be independently associated with a higher incidence of operative delivery, prolonged labor and persistent occiput posterior position . Although several maternal and fetal variables, such as fetal position, presentation or uterine contractions may influence labor, fetal head size and shape of birth canal are the major determinants in predicting a spontaneous vaginal birth . Despite this, there is no objective evidence yet on the actual role on combined assessment of fetal head and maternal pelvis in predicting the outcome of labor.…”

Cultural Evolutionary Neuroscience

“…The genetic evolution of our anatomy and physiology has progressed in tandem with the cultural evolution of our adaptive knowledge, and the trajectory of human brain evolution sits squarely within this intersection of genetic and cultural Oxford Handbook of Cultural Neuroscience and Global Mental Health Forthcoming evolution (Muthukrishna, Doebeli, Chudek, & Henrich, 2018a). Cultural practices such as food sharing (Kaplan, Hill, Lancaster, & Hurtado, 2000a), cooking (Wrangham & Carmody, 2010a), midwifery (Rosenberg & Trevathan, 2002), and modern medical interventions (Lipschuetz et al, 2015) support our large, costly, difficult-to-birth brains, while reciprocally, our enlarged brains support the storage and transmission of more complex cultural knowledge. This process of brain-culture coevolution has allowed human cultural complexity to scale up in dramatic ways, and so cultural transmission is intrinsic to the evolutionary and functional history of our nervous systems (Muthukrishna, Doebeli, Chudek, & Henrich, 2018b;Muthukrishna & Henrich, 2016a).…”