Growth During Early Teenage Pregnancy

Harrison, KelseyA.; Briggs, N. D.; John, CT; Memberr, M. T.; Lolomari, D.O.

doi:10.1016/s0140-6736(88)92046-6

Cited by 3 publications

(1 citation statement)

References 4 publications

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“…In Holland, for example, average female stature increased from around 154 cm in 1840 to 171 cm in the 1997, an average gain of 1.26 cm per decade [84,85]. In turn, increases in female stature are associated with larger pelvic dimensions and a reduced risk of cephalopelvic disproportion and caesarean section [81][82][83]86,87]. However, whilst much attention has been given to recent upward trends in size in European populations, negative trends have been observed in many populations.…”

Section: Secular Trends In Body Sizementioning

confidence: 99%

Between Scylla and Charybdis: renegotiating resolution of the ‘obstetric dilemma’ in response to ecological change

Wells¹

2015

Phil. Trans. R. Soc. B

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Hominin evolution saw the emergence of two traits-bipedality and encephalization-that are fundamentally linked because the fetal head must pass through the maternal pelvis at birth, a scenario termed the 'obstetric dilemma'. While adaptive explanations for bipedality and large brains address adult phenotype, it is brain and pelvic growth that are subject to the obstetric dilemma. Many contemporary populations experience substantial maternal and perinatal morbidity/mortality from obstructed labour, yet there is increasing recognition that the obstetric dilemma is not fixed and is affected by ecological change. Ecological trends may affect growth of the pelvis and offspring brain to different extents, while the two traits also differ by a generation in the timing of their exposure. Two key questions arise: how can the fit between the maternal pelvis and the offspring brain be 'renegotiated' as the environment changes, and what nutritional signals regulate this process? I argue that the potential for maternal size to change across generations precludes birthweight being under strong genetic influence. Instead, fetal growth tracks maternal phenotype, which buffers short-term ecological perturbations. Nevertheless, rapid changes in nutritional supply between generations can generate antagonistic influences on maternal and offspring traits, increasing the risk of obstructed labour.

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Section: Secular Trends In Body Sizementioning

confidence: 99%

Between Scylla and Charybdis: renegotiating resolution of the ‘obstetric dilemma’ in response to ecological change

Wells¹

2015

Phil. Trans. R. Soc. B

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The obstetric dilemma: An ancient game of Russian roulette, or a variable dilemma sensitive to ecology?

Wells¹,

DeSilva

Stock³

2012

American J Phys Anthropol

185

237

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The difficult birth process of humans, often described as the ''obstetric dilemma,'' is commonly assumed to reflect antagonistic selective pressures favoring neonatal encephalization and maternal bipedal locomotion. However, cephalo-pelvic disproportion is not exclusive to humans, and is present in some primate species of smaller body size. The fossil record indicates mosaic evolution of the obstetric dilemma, involving a number of different evolutionary processes, and it appears to have shifted in magnitude between Australopithecus, Pleistocene Homo, and recent human populations. Most attention to date has focused on its generic nature, rather than on its variability between populations. We reevaluate the nature of the human obstetric dilemma using updated hominin and primate literature, and then consider the contribution of phenotypic plasticity to variability in its magnitude. Both maternal pelvic dimensions and fetal growth patterns are sensitive to ecological factors such as diet and the thermal environment. Neonatal head girth has low plasticity, whereas neonatal mass and maternal stature have higher plasticity. Secular trends in body size may therefore exacerbate or decrease the obstetric dilemma. The emergence of agriculture may have exacerbated the dilemma, by decreasing maternal stature and increasing neonatal growth and adiposity due to dietary shifts. Paleodemographic comparisons between foragers and agriculturalists suggest that foragers have considerably lower rates of perinatal mortality. In contemporary populations, maternal stature remains strongly associated with perinatal mortality in many populations. Long-term improvements in nutrition across future generations may relieve the dilemma, but in the meantime, variability in its magnitude is likely to persist. Yrbk Phys The notion that maternal pelvic dimensions are subject to powerful competing demands from reproduction and locomotion is widely accepted in the biomedical and anthropological literature (Krogman, 1951;Washburn, 1960;Schultz, 1969;Rosenberg, 1992;Rosenberg and Trevathan, 1996;Wittman and Wall, 2007;Walsh, 2008;Franciscus, 2009;Trevathan, 2011). The maternal pelvis is frequently considered to be subject to two counteracting evolutionary forces: decreased height and increased mediolateral breadth in order to optimize the biomechanics of locomotion, and increased anteroposterior dimensions in order to enable birth of the unusually encephalized human infant. The compromise imposed by these antagonistic demands manifests as a difficult passage of the fetal head through the birth canal (Wittman and Wall, 2007), resulting in the birth process being a more complex and lengthy procedure in humans than in closely related species of ape (Tevathan, 1988;Rosenberg, 1992;Rosenberg and Trevathan, 2002). The antagonistic interaction of bipedalism and encephalization has been assumed to have followed the emergence of the large Homo brain within the last 2 million years (Martin, 1983).In addition to shaping the unusual mechanism of birth, h...

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Provision of Reproductive Health Services for Adolescents ‐‐ Report of a Study in Two Local Government Areas (LGAs) of Nigeria

Olukoya¹

1996

Early Child Development and Care

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Growth During Early Teenage Pregnancy

Cited by 3 publications

References 4 publications

Between Scylla and Charybdis: renegotiating resolution of the ‘obstetric dilemma’ in response to ecological change

Between Scylla and Charybdis: renegotiating resolution of the ‘obstetric dilemma’ in response to ecological change

The obstetric dilemma: An ancient game of Russian roulette, or a variable dilemma sensitive to ecology?

Provision of Reproductive Health Services for Adolescents ‐‐ Report of a Study in Two Local Government Areas (LGAs) of Nigeria

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