Effects of Breastfeeding on the Mother

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Breastfeeding is a unique biological heritage potentially shared by women everywhere. The hormones of breastfeeding aid in the adjustment to mothering, in conservation of energy, and in subsequent nutrient recovery. Because the physiologic processes of breastfeeding are a normal part of the maturation of the female body, it is not surprising that breastfeeding seems to have the attributes of a preventive health measure for women: Breastfeeding is beneficial for women's health. The sequelae of breastfeeding, and of having breastfed, are not minor: Breastfeeding, sometimes referred to as the final stage of labor, reduces the risk for (1) postpartum blood loss by increasing the rate of uterine contraction, (2) premenopausal breast cancer, and (3) ovarian cancer. In addition to reducing the severity of anemia, breastfeeding may cause other changes that may help to protect mothers against bladder and other infections. Also, epidemiologic studies seem to indicate that, despite the apparent bone loss that occurs in women during lactation, women who breastfeed may be at reduced risk for spinal and hip fracture after menopause. In addition to the direct health effects, breastfeeding seems to provide a sense of bonding, a sense of well-being, and an improved sense of self-esteem for many women.

These statements are considered controversial. This article explores several of these issues in a manner designed to aid in the understanding of why controversy surrounds breastfeeding research findings and, perhaps, why emotions or personal experiences may affect scientific interpretation in this field.

Section snippets

REASONS FOR CONFLICTING INTERPRETATION OF FINDINGS

Research-design and analysis-based and conviction-based reasons exist for conflicting interpretation of the studies of breastfeeding.

Research design–based issues include:

  • Different definitions of the characteristic under study. Internationally recognized definitions of breastfeeding exist.29 Nonetheless, many journals still accept articles without definitions of terms. Some publications, for example, still use the term exclusive breastfeeding to mean that breastfeeding is the only source

BREAST CANCER

Studies of the association of breast cancer with breastfeeding have fostered dialogue in the literature. In the 1920s, investigators found that breasts that never were used to breastfeed were more likely to become cancerous, but findings in the 1970s (when breastfeeding was at its lowest rate in the United States) associated age at first birth as the more important risk factor. The possibility of the association of breastfeeding and decreased breast-cancer risk resurfaced in the 1980s, and

OVARIAN CANCER

Breastfeeding has long been considered a potential cancer-preventive behavior and, in the 1970s, Casagrande et al6 hypothesized the “incessant ovulation” theory as a cause of ovarian cancer, linking the “excess” ovulation and concomitant epithelial irritation caused by fewer pregnancies and lack of breastfeeding to the observed increase in ovarian cancer. In 1983, Risch et al57 found a protective effect of lactation (RR, 0.79 per year of lactation) in a retrospective study of newly diagnosed

OSTEOPOROSIS

Apparent conflict exists between the clinical studies that show bone loss during lactation and the later mixed findings among retrospective epidemiologic studies that assess bone status at menopause.7, 25, 26, 35, 44, 72 Detractors often expand on these apparent conflicts without considering the biological basis and the interactions that may reveal a consensus. The better approach is to review all literature on a subject and to understand what mechanisms could allow all the findings to be

MATERNAL HUMAN IMMUNODEFICIENCY VIRUS AND BREASTFEEDING

Many health agencies, including the Centers for Disease Control and Prevention (CDC), now suggest that infected mothers should not breastfeed their infants to avoid the chance of mother-to-child viral transmission (MTCT) by this route. Where testing is available, replacement feeding is of high quality, and where good health care is accessible, the balance for the survival of the infant favors the use of replacement feeding. Although this may seem logical on first consideration, little is known

BREASTFEEDING AND FERTILITY

Breastfeeding is associated with increased child spacing. Medical literature from Aristotle, the Renaissance, and occasionally thereafter noted that women who suckle are less likely to become pregnant. The phenomenon was forgotten or disbelieved in recent decades as infant feeding substitutes replaced breastfeeding behaviors. Scientific evidence compiled by the social sciences, demonstrating the population level effect of breastfeeding on fertility, and the medical sciences, which now have

NUTRITIONAL STATUS AND BREASTFEEDING

Lactation demands maternal nutrient stores and intake. In regions where women are malnourished, a downward spiral from generation to generation may occur in which each new generation has a poor energy, protein, and micronutrient start on life that can never fully be replaced. Unfortunately, the approach in the past has been to try to supplement the infant. The result is shortened breastfeeding duration with concomitant increased disease and shortened interpregnancy interval, resulting in

MENTAL HEALTH AND BONDING

The author finds the literature on mental health and mother–infant bonding sparse and unconvincing. Although much of the literature is scientifically sound, the questions asked rarely directly address the issue of breastfeeding, and when they do, proper definition and timing of pattern shifts in breastfeeding are lacking.2, 46 Nonetheless, the biological plausibility that hormonal shifts might be associated with depression seems to be borne out in some studies,68 and the sense of empowerment

SUMMARY

In the rush to find nutrient alternatives to breastfeeding, a theme that dominated research on infant feeding throughout the twentienth century, only recently have new findings that reconfirm the importance of breastfeeding for maternal and child health begun to influence medical texts and health policy. Approximately 30 years of increasingly rigorous and positive research findings have led to the rediscovery of breastfeeding as a valid and evidence-based health intervention for infants.

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      Citation Excerpt :

      The benefits for infants and mothers of breastfeeding are well documented (Labbok, 2001; Lawrence, 2000).

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    Address reprint requests to Miriam H. Labbok, MD, MPH, IBCLC 4707 Connecticut Avenue Apartment 301 Washington, DC 20008

    Basic review prepared while Associate Professor and Director, Breastfeeding and MCH, WHO Collaborating Center on Breastfeeding (IBCC), Department of Obstetrics and Gynecology, Georgetown University Medical Center. Preparation of this review was supported in part under a Cooperative Agreement with United States Agency for International Development (USAID). The views expressed by the author in this article do not necessarily reflect the views or policies of Georgetown, USAID, Johns Hopkins University, or Tulane University.

    Earlier versions of this article were printed in the newsletter of the Australian College of Lactation in 1997 and as a review in Clinics in Perinatology 26:491–503, 1999.

    *

    Nutritional and Maternal Health Division, United States Agency for International Development, Washington, DC; Johns Hopkins University School of Public Health; and Tulane University School of Public Health, Baltimore, Maryland

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