Aspects of Praematurity and Dysmaturity

1. Front Matter

   Pages I-XI

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2. Role of the Placenta

   1. Front Matter

      Pages 1-1

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   2. Aspects of Steroid Metabolism in the Foeto-Placental Unit and the Newborn Infant

      • John W. Reynolds

      Pages 3-20

   3. Problems in the Pathologic Study of the Placenta

      • P. Gruenwald

      Pages 21-23

3. Back Matter

   Pages 25-34

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4. Assessment of Foetal Development

   1. Front Matter

      Pages 35-35

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   2. Growth Pattern of the Normal and the Deprived Fetus

      • P. Gruenwald

      Pages 37-45

   3. The Assessment of Foetal age by the Examination of the Central Nervous System

      • A. Minkowski, S. Saint-Anne Dargassies, C. Dreyfus-Brisac, J. Cl. Larroche, J. Vignaud, C. Amiel

      Pages 46-56

   4. Developmental Changes in Fetal Hemoglobin

      • H. C. Schwartz, T. J. Gribble, F. Welland, W. Nijhof, J. H. P. Jonxis

      Pages 57-67

   5. Developmental Changes in Liver Enzyme Activities with Special Reference to the Perinatal Period of Life

      • Fabio Sereni, Benedetta Luppis

      Pages 68-90

   6. Development of Enzymes and Absorption Processes in the Small Intestine of Human Fetus

      • O. Koldovský, A. Heringová, V. Jirsová, J. Kraml, H. Pelichová, J. Uher

      Pages 91-98

5. Back Matter

   Pages 99-116

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6. Experimental Aspects of Dysmaturity

   1. Front Matter

      Pages 117-117

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   2. Dysmaturity in the Experimental Animal

      • J. S. Wigglesworth

      Pages 119-126

   3. Effects of Prematurity and Dysmaturity in Animals

      • E. M. Widdowson

      Pages 127-137

7. Back Matter

   Pages 139-146

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8. Hereditary and Environmental Aspects of Low Birthweight

   1. Front Matter

      Pages 147-147

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   2. Factors Influencing Fetal Growth

      • L. O. Lubchenco, C. Hansman, Leena Bäckström

      Pages 149-166

   3. The Regulation of Foetal Growth

      • Margaret Ounsted

      Pages 167-188

9. Back Matter

   Pages 189-197

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The concept of the foeto-placental unit as an integrated endocrine organ has been defined recently by many in vivo studies at the 17th- 20th week of gestation. A functioning foeto-placental unit is necessary for most of the increased oestrogen production of pregnancy and for the provision of glucocorticoids and aldosterone to the foetus. Neither the foetus nor the placenta alone have the necessary enzyme systems for the synthesis of these groups of steroids. However, when the foetus and placenta function as a unit, all of the enzyme systems are present for the synthesis of these steroids from circulating cholesterol. The placenta, but not the mid-gestation foetal adrenal, can synthesize physiologically significant amounts of pregnenolone from circulating cholesterol. Part of the pregnenolone is converted to progesterone in the placenta by the 3~-HSD system (absent in the foetus). The progesterone is transferred to the foetus where it is transformed by C-II, C-17, C-18 and C-21 hydroxylases (all absent in the placenta) to cortisol, corticosterone and aldosterone. Pregnenolone transferred from the placenta to the foetus undergoes 171X-hydroxylation, side­ chain splitting and sulfurylation (absent in the placenta) and is converted to DHAS. The DHAS may undergo 161X-hydroxylation (absent in the placenta) in the foetal liver and be transported to the placenta as 161X-OH-DHAS. There it is subjected to a neutral steroid sulfatase (absent in the foetus) and is converted to oestriol by action of the 3~-HSD system and the aromatizing enzyme system.

• birth
• complications
• fetus
• growth
• placenta
• regulation

• Dept. Paediatics, State University, Groningen, Netherlands

  J. H. P. Jonxis, J. A. Troelstra

• Dept. Paediatics, Medical School, Rotterdam, Netherlands

  H. K. A. Visser

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