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Is preterm birth a human-specific syndrome?

Phillips JB, Abbot P, Rokas A - Evol Med Public Health (2015)

Bottom Line: Within species, gestation length is normally distributed, and all species appear to occasionally give birth before the 'optimal' time.Furthermore, human gestation length, like that of many mammalian species, scales proportionally to body mass, suggesting that this trait, like many others, is constrained by body size.Describing PTB broadly in mammals opens avenues for comparative studies on the physiological and genetic regulators of birth timing as well as the development of new mammalian models of the disease.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Vanderbilt University, VU Station B 35-1364, Nashville, TN 37235, USA.

No MeSH data available.


Related in: MedlinePlus

Intra-species variation in gestation length is similar among many mammals. (A) We collected the arithmetic means and standard deviations, when available, in days for all placental mammals with complete genomes. Sample sizes ranged from 2 to 17 000, with a median of 104. In all cases, only live births were considered. Examination of the potential for skew in model choice (normal vs log-normal) showed that the mean squared error between the two distributions was likely well below the error in measurement of gestation lengths reported in the original research. Boxes contain the mean plus/minus 1 SD; whiskers extend to plus/minus 3 SD. Vertical lines indicate 92.5% completed gestation time suggesting each species experiences ‘preterm’ birth according to the human definition with the exclusion of horses, goats and rodents. (B) Comparison of the coefficient of variation across species. Plots and analysis were performed using the ggplot2 package in R 3.1.2 [122, 123]. References for each species can be found as follows: human [25], chimpanzee [29], gorilla [124], orangutan [125], long-tailed macaque and rhesus macaque [126], baboon [127], marmoset [128], rat and rabbit [129], guinea pig [24], goat and mouse [130], cow [131] and horse [132]
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eov010-F1: Intra-species variation in gestation length is similar among many mammals. (A) We collected the arithmetic means and standard deviations, when available, in days for all placental mammals with complete genomes. Sample sizes ranged from 2 to 17 000, with a median of 104. In all cases, only live births were considered. Examination of the potential for skew in model choice (normal vs log-normal) showed that the mean squared error between the two distributions was likely well below the error in measurement of gestation lengths reported in the original research. Boxes contain the mean plus/minus 1 SD; whiskers extend to plus/minus 3 SD. Vertical lines indicate 92.5% completed gestation time suggesting each species experiences ‘preterm’ birth according to the human definition with the exclusion of horses, goats and rodents. (B) Comparison of the coefficient of variation across species. Plots and analysis were performed using the ggplot2 package in R 3.1.2 [122, 123]. References for each species can be found as follows: human [25], chimpanzee [29], gorilla [124], orangutan [125], long-tailed macaque and rhesus macaque [126], baboon [127], marmoset [128], rat and rabbit [129], guinea pig [24], goat and mouse [130], cow [131] and horse [132]

Mentions: All quantitative traits, such as human height [18–20], have a continuous range of variation. In this context, we expect the presence of measurable variance in reproductive traits. For example, long-term population studies in British islands, such as with Soay sheep in St Kilda island and red-tailed deer on the Isle of Rum, have uncovered abundant variation in longevity, age at primiparity, lifetime fecundity and lifetime reproductive success [21–23], and have provided strong evidence for the heritability of such variation [21, 22]. For example, the average lifetime fecundity in the Ram Mountain population of Soay sheep is 5.3 lambs, ranging from 0 to 15, and its estimated heritability is significantly larger than zero, suggesting that this reproductive trait is not only variable, but that its variance has a heritable component [23]. The insights we have gained from these long-term studies on variation in reproductive traits suggest that heritable variation in gestation length, like other reproductive traits, should also be a general feature of mammalian life history. Indeed, gestation length data from diverse placental mammals show that all experience variation in birth timing (Fig. 1). For example, guinea pigs, Cavia porcellus, have gestation lengths ranging from 8.5 to 10 weeks [24], whereas humans have gestation lengths ranging from 28 to 50 weeks [25]. From Fig. 1, we see there is no expectation from life-history theory that gestation length variation is absent in mammals generally, nor is there evidence that variation in human gestation length is remarkable or unusual compared to other mammal species, particularly other primates.Figure 1.


Is preterm birth a human-specific syndrome?

Phillips JB, Abbot P, Rokas A - Evol Med Public Health (2015)

Intra-species variation in gestation length is similar among many mammals. (A) We collected the arithmetic means and standard deviations, when available, in days for all placental mammals with complete genomes. Sample sizes ranged from 2 to 17 000, with a median of 104. In all cases, only live births were considered. Examination of the potential for skew in model choice (normal vs log-normal) showed that the mean squared error between the two distributions was likely well below the error in measurement of gestation lengths reported in the original research. Boxes contain the mean plus/minus 1 SD; whiskers extend to plus/minus 3 SD. Vertical lines indicate 92.5% completed gestation time suggesting each species experiences ‘preterm’ birth according to the human definition with the exclusion of horses, goats and rodents. (B) Comparison of the coefficient of variation across species. Plots and analysis were performed using the ggplot2 package in R 3.1.2 [122, 123]. References for each species can be found as follows: human [25], chimpanzee [29], gorilla [124], orangutan [125], long-tailed macaque and rhesus macaque [126], baboon [127], marmoset [128], rat and rabbit [129], guinea pig [24], goat and mouse [130], cow [131] and horse [132]
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4493222&req=5

eov010-F1: Intra-species variation in gestation length is similar among many mammals. (A) We collected the arithmetic means and standard deviations, when available, in days for all placental mammals with complete genomes. Sample sizes ranged from 2 to 17 000, with a median of 104. In all cases, only live births were considered. Examination of the potential for skew in model choice (normal vs log-normal) showed that the mean squared error between the two distributions was likely well below the error in measurement of gestation lengths reported in the original research. Boxes contain the mean plus/minus 1 SD; whiskers extend to plus/minus 3 SD. Vertical lines indicate 92.5% completed gestation time suggesting each species experiences ‘preterm’ birth according to the human definition with the exclusion of horses, goats and rodents. (B) Comparison of the coefficient of variation across species. Plots and analysis were performed using the ggplot2 package in R 3.1.2 [122, 123]. References for each species can be found as follows: human [25], chimpanzee [29], gorilla [124], orangutan [125], long-tailed macaque and rhesus macaque [126], baboon [127], marmoset [128], rat and rabbit [129], guinea pig [24], goat and mouse [130], cow [131] and horse [132]
Mentions: All quantitative traits, such as human height [18–20], have a continuous range of variation. In this context, we expect the presence of measurable variance in reproductive traits. For example, long-term population studies in British islands, such as with Soay sheep in St Kilda island and red-tailed deer on the Isle of Rum, have uncovered abundant variation in longevity, age at primiparity, lifetime fecundity and lifetime reproductive success [21–23], and have provided strong evidence for the heritability of such variation [21, 22]. For example, the average lifetime fecundity in the Ram Mountain population of Soay sheep is 5.3 lambs, ranging from 0 to 15, and its estimated heritability is significantly larger than zero, suggesting that this reproductive trait is not only variable, but that its variance has a heritable component [23]. The insights we have gained from these long-term studies on variation in reproductive traits suggest that heritable variation in gestation length, like other reproductive traits, should also be a general feature of mammalian life history. Indeed, gestation length data from diverse placental mammals show that all experience variation in birth timing (Fig. 1). For example, guinea pigs, Cavia porcellus, have gestation lengths ranging from 8.5 to 10 weeks [24], whereas humans have gestation lengths ranging from 28 to 50 weeks [25]. From Fig. 1, we see there is no expectation from life-history theory that gestation length variation is absent in mammals generally, nor is there evidence that variation in human gestation length is remarkable or unusual compared to other mammal species, particularly other primates.Figure 1.

Bottom Line: Within species, gestation length is normally distributed, and all species appear to occasionally give birth before the 'optimal' time.Furthermore, human gestation length, like that of many mammalian species, scales proportionally to body mass, suggesting that this trait, like many others, is constrained by body size.Describing PTB broadly in mammals opens avenues for comparative studies on the physiological and genetic regulators of birth timing as well as the development of new mammalian models of the disease.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Vanderbilt University, VU Station B 35-1364, Nashville, TN 37235, USA.

No MeSH data available.


Related in: MedlinePlus