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The material contained in this volume was submitted as previously unpublished material, except in the instances in which credit has been given to the source from which some of the illustrative material was derived.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. She is a leading nutritional epidemiologist from the great but still largely underprivileged country of India, based in India's National Institute of Nutrition, right in the centre of that astonishing subcontinent. Her presence and counsel were especially valuable to us. Finally, we have included three appendices. The first describes a model, devised by Jean-Pierre Habicht, and includes a list of the consequences arising from such a model, discussed in the light of our workshop. The second is a brief general commentary by a demographer, John Hobcraft, who must sometimes have been a little impatient with our greater emphasis on biological and medical issues than on the demographic. He nevertheless also takes us to task sometimes for some of our shaky biology and medicine. The third appendix is a personal attempt by Habicht to summarise some of our agreements as well as areas of uncertainty. Although he was helped in this by other participants, this remains his personal summary. The general reader will ask, quite reasonably, What is the answer? It is sometimes an unfortunate but realistic consequence of this design of workshop that no clear answer appears to emerge, for the very good reason that the question we set out to investigate was itself not very clear. All kinds of people, as well as governments and international agencies, may be impatient with that reply, but it will do them (and the media) no harm to be forced to the same conclusion which is banal for the expert: real life is often so scientifically messy that it cannot always be crisply described. Certainly, the mother's nutritional state has a role in lactational facility. But the size of that role in the multiplicity of different natural circumstances is beyond description and might remain so even if we ever succeeded in measuring all the important major variables, which no one has yet done. In the end, we may have to be satisfied with practical policies which draw more on our humanity than our science, such as that we should feed poverty-stricken mothers and babies. However this may be, feeding them as a solitary intervention which can be counted on, like all others, to upset a carefully evolved ecology, risks harm as well as benefit unless a more multiple and intelligent intervention is devised. It seems clear that additional methods for promoting greater birth spacing will have to accompany our nutritional intervention if our original humanity is not to risk adding to an viii PREFACE almost desperate demographic problem. The most our book can do is to set out the truth—about our ignorance, about the frightening complexity which emerges from a seemingly simple question when it is properly examined, and about responsible current opinion on what the answer may turn out to be. For my own part I shall be rewarded if the book adequately reflects our delib- erations, and if these contribute, in however small a way, to any relief of the suffering of the majority of mothers and children who are currently bearing the brunt of massive world poverty.

JOHN DOBBING

REFERENCES 1. Dobbing J. Breast is best, isn't it? In Freed DJL, ed. Health hazards of milk. London: Bailliere Tindall, 1984. 2. Dobbing J, ed. Maternal nutrition in pregnancy: eating for two? London: Academic Press, 1981. 3. Dobbing J, ed. Prevention of spina bifida and other neural tube defects. London: Academic Press, 1983. 4. Dobbing J, ed. Scientific studies in mental retardation. London: McMillan, 1984. Foreword

A return to the source can be a very refreshing experience. Four years ago, Professor John Dobbing organized the first Nestld Nutrition Workshop, on maternal nutrition, at the same time experimenting with a new style in which a very small number of participants, instead of formally presenting papers, replied to comments and questions from other participants on the basis of the previously circulated papers. In this way, the entire period of the workshop could more fruitfully be devoted to our in-depth discussion. Since that time, seven more conventional but nevertheless very successful work- shops have been organized in which about 30 minutes are allowed for the presen- tation of a paper followed by about 60 minutes for discussion. This procedure has the advantage of allowing a large number of papers to be discussed without stifling the healthy confrontation between scientist and clinicians. We are particularly pleased for this ninth workshop, again on the subject of maternal nutrition, to have had Professor Dobbing in the chair for a workshop with no formal presentations whatsoever. The in-depth discussion generated by the twelve specialists on the physiology of human reproduction and nutrition proved to be most interesting, as was to be expected. Whereas it is true that some topics are better suited to study by a smaller group than others, we intend to continue to alternate both types of meeting within the Nestle Nutrition Workshop Series for the added interest of participants and readers alike.

PIERRE R. GUESRY, M.D. Vice President Nestle Products Technical Assistance Co. Ltd. Medical and Scientific Manager Infant and Dietetic Products Department

IX Acknowledgments

As Chairman of the Ninth Nestle Nutrition Workshop and Editor of this volume, I cannot adequately thank all those already mentioned, as well as the others whose signed commentaries appear in the book. A most productive workshop and, I hope, an equally useful book could not have happened without the generous sponsorship of Nestle Nutrition. I would particularly like to thank Yves Barbieux, Head, Infant Food Section at Nestle headquarters, and Pierre Guesry, Medical Director, who both attended and contributed most usefully to the proceedings. I would especially like to thank Irene Warrington, who was responsible for the enormous task of the precirculation of the papers and all the preconference corre- spondence; and Sian Nash and Jean Sands, who helped me with the scientific arrangements at the meeting. Pat Wright and Ron Hendey organized those important practical matters which were the foundations of our comfort and enjoyment.

XI