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Chapter IV. Fecundity

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Family Growth in Metropolitan America
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Chapter IV. Fecundity DEFINITION OF FECUNDITY The couple who want another child as rapidly as possible cannot be certain either that conception will be immediate or that pregnancy will eventuate in a live birth. After stopping contraception, they have to wait, sometimes many months, for conception. Because of post­partum sterility, the wait tends to be longer if they have just had a birth and are seeking another pregnancy without an interlude of contraception. Then also, given pregnancy, the couple faces a risk of pregnancy wastage, which defers the next birth until after another wait for conception and approximately nine months of pregnancy. Thus, any couple is subject to involuntary factors of fertility regulation expressed in the twin possibilities of conception delay and pregnancy wastage. A couple is absolutely sterile either if their monthly probability of conception is zero, or if their chances are zero that pregnancy will lead to a live birth. In one case, there is an indefinite wait for pregnancy; in the other, there is habitual abortion. If both these probabilities are greater than zero, then the couple is fecund. But fecundity is a matter of degree, varying over a wide range, and to give it precision it is necessary to consider both the couple's monthly chance of conception and their risk of pregnancy wastage. RISK OF PREGNANCY WASTAGE1 It is commonly supposed that most women are subject to a uniform, low risk of pregnancy wastage which acts as though determined by a host of small factors, with little correlation obtaining between presence and absence of wastage in consecutive birth intervals.2 For a 1 At issue here is recognized pregnancy wastage, because, as Rock and Hertig stress, many early abortions go undetected. From their operations on 150 multipara, the authors estimate that as high as 30 to 40 per cent of all menstrual cycles may be associated with defective ova or early abortions. See A. T. Hertig and J. Rock, "A Series of Potentially Abortive Ova Recovered from Fertile Women Prior to Their First Missed Menstrual Period," American Journal of Obstetrics and Gynecology, 58 (1949), 968-993. Hertig comments further on this pioneering research project in E. T. Engle, ed., Pregnancy Wastage, Charles C. Thomas, Springfield, 111., 1953, p. 18. This finding of Hertig and Rock does not so much invalidate existing statistics on pregnancy wastage as it redefines them. These statistics measure merely that part of pregnancy wastage which is recognized as such by informants. 8 One attempt to demonstrate this generalization directly is F. J. Schoeneck's analysis of pregnancy wastage among 776 women having 5 or more pregnancies, "Pregnancy Patterns and Fetal Salvage," Obstetrics and Gynecology, 1 (1953), 610-614.
© 2016 Princeton University Press, Princeton

Chapter IV. Fecundity DEFINITION OF FECUNDITY The couple who want another child as rapidly as possible cannot be certain either that conception will be immediate or that pregnancy will eventuate in a live birth. After stopping contraception, they have to wait, sometimes many months, for conception. Because of post­partum sterility, the wait tends to be longer if they have just had a birth and are seeking another pregnancy without an interlude of contraception. Then also, given pregnancy, the couple faces a risk of pregnancy wastage, which defers the next birth until after another wait for conception and approximately nine months of pregnancy. Thus, any couple is subject to involuntary factors of fertility regulation expressed in the twin possibilities of conception delay and pregnancy wastage. A couple is absolutely sterile either if their monthly probability of conception is zero, or if their chances are zero that pregnancy will lead to a live birth. In one case, there is an indefinite wait for pregnancy; in the other, there is habitual abortion. If both these probabilities are greater than zero, then the couple is fecund. But fecundity is a matter of degree, varying over a wide range, and to give it precision it is necessary to consider both the couple's monthly chance of conception and their risk of pregnancy wastage. RISK OF PREGNANCY WASTAGE1 It is commonly supposed that most women are subject to a uniform, low risk of pregnancy wastage which acts as though determined by a host of small factors, with little correlation obtaining between presence and absence of wastage in consecutive birth intervals.2 For a 1 At issue here is recognized pregnancy wastage, because, as Rock and Hertig stress, many early abortions go undetected. From their operations on 150 multipara, the authors estimate that as high as 30 to 40 per cent of all menstrual cycles may be associated with defective ova or early abortions. See A. T. Hertig and J. Rock, "A Series of Potentially Abortive Ova Recovered from Fertile Women Prior to Their First Missed Menstrual Period," American Journal of Obstetrics and Gynecology, 58 (1949), 968-993. Hertig comments further on this pioneering research project in E. T. Engle, ed., Pregnancy Wastage, Charles C. Thomas, Springfield, 111., 1953, p. 18. This finding of Hertig and Rock does not so much invalidate existing statistics on pregnancy wastage as it redefines them. These statistics measure merely that part of pregnancy wastage which is recognized as such by informants. 8 One attempt to demonstrate this generalization directly is F. J. Schoeneck's analysis of pregnancy wastage among 776 women having 5 or more pregnancies, "Pregnancy Patterns and Fetal Salvage," Obstetrics and Gynecology, 1 (1953), 610-614.
© 2016 Princeton University Press, Princeton

Chapters in this book

  1. Frontmatter i
  2. Foreword vii
  3. Preface ix
  4. Contents xiii
  5. Tables xv
  6. Part I. Introduction
  7. Chapter I. Background, Objectives, and Approach 5
  8. Chapter II. Study and Sample Design 16
  9. Chapter III. Methodology 29
  10. Part II. Fertility Variables
  11. Introduction to Part II 43
  12. Chapter IV. Fecundity 45
  13. Chapter V. Contraception 70
  14. Chapter VI. Birth Intervals 103
  15. Chapter VII. Preferred Birth Intervals 115
  16. Chapter VIII. Desired Family Size 136
  17. Chapter IX. Summary of the Fertility Variables 149
  18. Part III. Social and Psychological Determinants
  19. Chapter X. Concepts and Hypotheses 163
  20. Chapter XI. Religion, Class, and Fertility 178
  21. Chapter XII. Religiousness 194
  22. Chapter XIII. Socio-Economic Status 212
  23. Chapter XIV. Social Mobility 237
  24. Chapter XV. Residence and Migration 263
  25. Chapter XVI. Age and Sex Composition of the Family 282
  26. Chapter XVII. Social Relations within the Family 298
  27. Chapter XVIII. Personality Characteristics 314
  28. Chapter XIX. Summary Multivariate Analysis 320
  29. Part IV. Resurvey
  30. Chapter XX. The Next Phase of the Study 339
  31. Appendices
  32. Appendix A. Supplement to Chapter IV 347
  33. Appendix Β. Supplement to Chapter V 359
  34. Appendix C. Index Construction 379
  35. Appendix D. Significance Levels of Correlation Coefficients 423
  36. Appendix Ε. Related Publications 424
  37. Author Index 426
  38. Subject Index 428
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https://doi.org/10.1515/9781400876419-008

Chapters in this book

  1. Frontmatter i
  2. Foreword vii
  3. Preface ix
  4. Contents xiii
  5. Tables xv
  6. Part I. Introduction
  7. Chapter I. Background, Objectives, and Approach 5
  8. Chapter II. Study and Sample Design 16
  9. Chapter III. Methodology 29
  10. Part II. Fertility Variables
  11. Introduction to Part II 43
  12. Chapter IV. Fecundity 45
  13. Chapter V. Contraception 70
  14. Chapter VI. Birth Intervals 103
  15. Chapter VII. Preferred Birth Intervals 115
  16. Chapter VIII. Desired Family Size 136
  17. Chapter IX. Summary of the Fertility Variables 149
  18. Part III. Social and Psychological Determinants
  19. Chapter X. Concepts and Hypotheses 163
  20. Chapter XI. Religion, Class, and Fertility 178
  21. Chapter XII. Religiousness 194
  22. Chapter XIII. Socio-Economic Status 212
  23. Chapter XIV. Social Mobility 237
  24. Chapter XV. Residence and Migration 263
  25. Chapter XVI. Age and Sex Composition of the Family 282
  26. Chapter XVII. Social Relations within the Family 298
  27. Chapter XVIII. Personality Characteristics 314
  28. Chapter XIX. Summary Multivariate Analysis 320
  29. Part IV. Resurvey
  30. Chapter XX. The Next Phase of the Study 339
  31. Appendices
  32. Appendix A. Supplement to Chapter IV 347
  33. Appendix Β. Supplement to Chapter V 359
  34. Appendix C. Index Construction 379
  35. Appendix D. Significance Levels of Correlation Coefficients 423
  36. Appendix Ε. Related Publications 424
  37. Author Index 426
  38. Subject Index 428
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