Fetal adaptation to stress: Part I: acceleration of fetal maturation and earlier birth triggered by placental insufficiency in humans
Introduction
Fetal stress has been a hot topic for decades, an important issue for both obstetricians and neonatologists in the peripartum management of the mother and infant. It has become clear recently that the effects of fetal stress, both short term and long term, both beneficial and adverse, are not only of interest for perinatology but also for evolutionary biology, for neurology and for adult medicine. This general review represents an attempt to bring together data from several disciplines, including authors from obstetrics, pediatric neurology, pediatric pulmonology and animal biology.
This review is presented in two parts: clinical data will be discussed in Part I: acceleration of maturation may occur in brain and lungs, as an adaptation to fetal stress. Early initiation of parturition may also be associated. These adaptive changes could represent a life-saving answer to moderate stress with resultant earlier birth of a more mature newborn, and increased survival as long as the unfavorable fetal environment is not too early or too severe.
Evolutionary aspects, experimental and epidemiological data on adult health will be discussed in Part II. The capacity to vary development in response to the environment is demonstrated in amphibians, in which the neuroendocrine stress system has been studied, with corticotropin releasing hormone as the primary player. Adverse long-term effects on hippocampal neurons have been studied in rats, as a consequence of prenatal stress. Finally, a new field of investigation opened in the 1990s with the Barker hypothesis, suggesting long-term effects of fetal undernutrition on the determination of chronic adult diseases.
Section snippets
Possible fetal adaptation to unfavorable circumstances
Questioning the so-called clockwork precision in fetal maturation was not politically correct in the 1960s as clinical dating in neonates relied on this postulated precision and has been accepted for 20 years. Some doubts however arose about the immutability of developmental processes with precise documentation of ovulation based on temperature curves and later by pregnancies obtained by stimulation of ovulation.
The first break in this dogma was the discovery by Gluck and Kulovich in 1973 [1],
Neurological assessment of maturation: methodological issues
Neurological assessment of maturation from 28 to 40 weeks gestation was initiated by Saint-Anne-Dargassies [17], [18] and later used and modified in various ways. The personal goal of one of us (Amiel-Tison) has been to select the most useful neurological criteria and to describe and illustrate the infant responses to make the exam both more appealing to clinicians and more reliable [19]. Additional simplification has resulted in a 10-item table (Table 1) [20], [21]. The originality of this
Are adaptive changes observed in the lung ?
During the 1970s and 1980s, a low incidence of respiratory distress syndrome (RDS) in neonates having experienced a shortage of nutrients such as in multiple pregnancies for instance [5] was observed. Within this period, biological observations tend to show that the L/S ratio in amniotic fluid was reaching mature levels earlier in maternal hypertensive pregnancies [30] as well as in twin pregnancies [31], therefore tending to demonstrate an accelerated fetal lung maturation (FLM). This
Natural history in pregnancy induced hypertension
It is necessary to go back to the natural history of preeclampsia, before modern management modified its spontaneous evolution; this means back to the 1960s, a time when the disease was well described but the therapeutic approach timid, when early CS for fetal rescue was not performed. Based on the Cleveland survey (1962–1968) [47] toxemic patients have a tendency to deliver earlier, as shown in Fig. 1, when comparing the birth frequency distribution for all primigravidae with that of
Conclusion
Conceptually new in the early 1970s, fetal adaptation to stress is now relying on various experimental data. However, uncertainties concerning a probable threshold (a GA below which adaptation does not occur) and the lack of biological criteria available during pregnancy are still responsible for skepticism about the usefulness of this body of knowledge for obstetrical management.
Since long ago, pediatricians were aware of remarkable survival in very preterm and very thin neonates who manage to
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Genetics, hormonal influences, and preterm birth
2017, Seminars in PerinatologyCitation Excerpt :These findings support the hypothesis that placental-derived CRH stimulates the release of fetal pituitary adrenocorticotropin (ACTH) to enhance fetal adrenal cortisol production which further stimulates placental CRH release. An important role of the fetus in stress-induced PTB has been recently proposed.77–79 Through the production of adrenal hormonal precursors, data supports the theory that the fetus actively participates in controlling the timing of labor.80
Relation between maternal antenatal anxiety and infants' weight depends on infants' sex: A longitudinal study from late gestation to 1-month post birth
2015, Journal of Psychosomatic ResearchCitation Excerpt :First, our data suggest that even mild anxiety influences fetal growth, thus showing again that stress-related modulation of fetal growth is not limited to severe conditions [63]. Second, our results suggest that fetal development can be accelerated in the context of mild challenge as has been reported in a few previous studies [48,52,64]. Third, it is important to point out that although effect sizes were small; even subtle deviations in infants' weight at birth can have significant long term detrimental effects on development, including cognitive development and educational achievement during childhood and on adults' response to stress and physical and mental health up to and beyond middle-age [[65–67]; reviews in [68–70]].
Parturition
2015, Knobil and Neill's Physiology of Reproduction: Two-Volume SetMaternal stress in pregnancy: Considerations for fetal development
2012, Journal of Adolescent HealthCitation Excerpt :We wonder whether the conceptualization of maternal stress originally as a developmental teratogen, and subsequently within a programming framework originally used to examine the role of prenatal undernutrition on adult metabolic disorders [87], may have canalized research toward a search for adverse outcomes in lieu of a broader perspective on the interplay between the maternal environment and the developing fetal brain. There is long-standing theoretical and empirical support for an inverted U-shaped association between stress and performance, as described by Yerkes and Dodson more than a century ago [88], consistent with the current view that the human brain requires sufficient, but not overwhelming, stress to promote optimal neural development both before [89] and after birth [90]. This perspective is consistent with the model of the role of early postnatal stress in the promotion of developmental adaptation as reflected by arousal regulation and resilience stress in nonhuman primates [91].