Maternal Nutrition and Lactational Infertility

Maternal Nutrition and Lactational Infertility

Maternal Nutrition and Lactational Infertility Editor John Dobbing D.Sc, F.R.C.P., F.R.C.Path. Department of Child Health University of Manchester Manchester, England Nestle Nutrition Workshop Series Volume 9 NESTLE NUTRITION, VEVEY RAVEN PRESS • NEW YORK Raven Press, 1140 Avenue of the Americas, New York, New York 10036 © 1985 by Nestl6 Nutrition S.A. and Raven Press Books, Ltd. All rights reserved. This book is protected by copyright. No part of it may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of Nestle Nutrition and Raven Press. Made in the United States of America Library of Congress Cataloging in Publication Data Main entry under title: Maternal nutrition and lactational infertility. (Nestld Nutrition workshop series ; v. 9) Based on papers discussed at the 9th Nestle Nutrition workshop held in England in 1984. Includes bibliographies and index. 1. Infertility, Female—Congresses. 2. Amenorrhea, Lactation—Congresses. 3. Mothers—Nutrition—Congresses. 4. Amenorrhea, Lactation—Endocrine aspects—Congresses. 1. Dobbing, John. II. NestlfS Nutrition S.A. III. Series. [DNLM: 1. Infertility, Female—complications—congresses. 2. Lactation—congresses. 3. Nutrition Disorders—compli- cations—congresses. W3 NE228 v.9 / WP 570 M425 1984] RG201.M38 1985 618.T78 85-1784 ISBN 0-88167-100-2 (Raven Press) The material contained in this volume was submitted as previously unpublished material, except in the instances in which credit has been given to the source from which some of the illustrative material was derived. Great care has been taken to maintain the accuracy of the information contained in the volume. However, Raven Press cannot be held responsible for errors or for any consequences arising from the use of the information contained herein. Contents Endocrine Control of Lactational Infertility. I 1 Alan S. McNeilly, Anna Glasier, and Peter W. Howie Endocrine Control of Lactational Infertility. II 25 Claude Robyn, Sylvain Meuris, and Philippe Hennart Maternal Nutrition and Lactational Infertility: The Baby in the Driving Seat 41 P. G. Lunn Maternal Nutrition and Lactational Amenorrhoea: Perceiving the Metabolic Costs 65 Rose E. Frisch Maternal Nutrition and Lactational Infertility: A Review 93 Prema Ramachandran Appendices Model for Analysis of the Relationship Between Breastfeeding Data and Postpartum Anovulation Data 119 J-P. Habicht and K.M. Rasmussen Comments from a Demographer 129 John Hobcraft Areas of Agreement and Uncertainty 139 J-P. Habicht Subject Index 143 Xlll Preface It has long been known that lactation reduces fecundity, and hence fertility; and it follows that prolonged lactation, such as occurs in traditional societies in devel- oping countries, must impose an important constraint on the number of births in communities where it is practised. The endocrinological and other mechanisms underlying this phenomenon are still far from completely understood, in spite of advances in knowledge in recent years. We also have an increasing awareness of the other restraints on reproduction, largely in the impoverished world, including the many cultural taboos restricting sexual activity during lactation, together with the growing use of modern methods of contraception. Cultural taboos, however, show signs of crumbling somewhat as traditional societies degenerate, a degeneracy which unfortunately often accompanies the otherwise civilizing influence of the privileged world in reducing that unacceptable level of maternal and infant mortality and morbidity which is also traditional and "natural." Our book sets out to analyze a more specific question related to lactational infertility, Does a poor maternal nutritional state contribute significantly to the efficacy of lactation as a contraceptive in underprivileged communities? This is not the first time the question has been asked, but recent intervention studies, in par- ticular those of R. G. Whitehead and his team in The Gambia, have reawakened interest in it. Clearly, if there is a price to pay for the demographic advantages of prolonged lactation, we had better know about that price, especially if nutritional and other badly needed aid to the underprivileged world should threaten to exac- erbate an already disquieting demographic problem. If that is true, it should be unnecessary to say that the practical consequences for future policy ought not to lead (as some have foolishly suggested) to a withholding of food aid where mothers and babies desperately need it, but to an additional effort to provide other fertility- limiting measures to replace those which may be reduced by nutritional intervention. It should also be unnecessary to reiterate that no one should wish to reduce either the prevalence or even the duration of breastfeeding, properly supplemented where necessary, provided that steps are taken to relieve both mothers and babies of any further burden in circumstances where they are already at the edge of tolerance. The paramount importance of breastfeeding, like Shakespeare's wine, needs no bush (1). Successful breastfeeding, however, should promote the proper growth of the baby, without detriment to the mother's health. Our book is a distillation for a wider readership of discussions which were held in late 1984 (in Shakespeare's own countryside) at a very special kind of workshop, the fourth of its kind (2-4). All the main papers were circulated long before the meeting to all the participants, who were each asked to consider them carefully and write a commentary on each; and these commentaries were also precirculated, vi PREFACE well before our getting together to discuss them. At the workshop itself there was no audience, and there was no need for anyone to give his paper, so that our time was entirely taken up with discussion and argument. Authors of both the papers and the commentaries were free to amend them in the light of the discussions, so that much of what appears in the book has been considerably refined by peer review in a way which goes far beyond that imposed on scientific papers in most learned journals and immeasurably more so than the usual chapters in other books or conference reports. As will be seen, there has been no attempt to reach a common denominator of consensus; rather, we have even sought to bring disagreement out into the open and display it for what it is: the lifeblood of scientific progress. Neither have we attempted a complete coverage of the topic. In particular, the professional demo- graphic and even the epidemiological aspects have been somewhat neglected in favour of the particularly medical and biological ones. Our deliberations were considerably enriched by John Hobcraft and Jean-Pierre Habicht, representing both of these important disciplines, and like all the other delegates, even they did not escape without some important modification of their own thinking, as well as making a great impression on our own. Indeed, as well as the visible product or our workshop which is this book, there were invisible ones which are unmeasurable but in some ways at least as useful. All of us were made to consider modification of our attitudes by contact with colleagues from our own and other disciplines, and this contact has certainly led to the serious planning of future collaborative and interdisciplinary research, which might not otherwise have occurred. Our sponsors, Nestle Nutrition, who were actively represented throughout the workshop by their medical director, Dr. Pierre Guesry, should find some reward, not only in the addition of this ninth monograph to their magnificent and growing series but also to this direct consequence of their expenditure: that leading researchers in a field of maternal and child nutrition have been thereby stimulated to collaborate, more than might otherwise have been the case, in their future work The book opens with two chapters on the present state of the endocrine art relating to our subject. Alan McNeilly and Claude Robyn have set out the grammar of our subject. Both chapters outline recent discoveries in the field as well as current responsible speculation and, just as important, some controversy. McNeilly's en- docrinological studies come from a research unit whose main brief is to make advances in contraceptive practice. He has contributed new findings to the contra- ceptive effects of lactation in a representative privileged community in Scotland. Robyn is a practising university professor of gynaecology in Belgium and has played an important part in a long-standing programme of field studies in central Africa, mainly in Zaire and Rwanda, led by H. L. Vis, a senior Belgian paediatrician who also contributed to our workshop. The two chapters on endocrinology are followed by one from Peter Lunn, a member of Roger Whitehead's team, whose important parallel field studies in The Gambia and in Cambridge (England) have, amongst many other things, led to the PREFACE vii renewed expression of our main question. New ideas on the possibly major im- portance of night feeding and on the concept of the baby's "driving role" in the mother-infant relationship are amongst the matters Lunn discusses, helped in the commentaries throughout the book by Whitehead, who himself played a welcome role throughout our workshop. There then follows a rather different chapter by Rose Frisch, coming from that other Cambridge (Massachusetts). Her long-standing hypothesis linking body fat and physical exercise to the timing of menarche as well as menopause is clearly related, in general terms, to the influence of nutrition on reproductive performance. The distinction between this aspect of her work and the one mainly addressed in our book and in other parts of her paper should not conceal the complementary nature of these two areas when it comes to analyzing their final effect on society. Prema Ramachandran, whose paper forms the foundation for the next chapter, has particular qualifications enabling her to help us in our enquiry.

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