Women’s Health Today

The effects of breastfeeding on a mother’s short and long-term health are important, yet many women are unaware of the potential risks associated with choosing not to breastfeed. Barbara Higham takes a look at what the research tells us about the health implications for breastfeeding mothers.

It’s no secret that breastfeeding is good for babies. The risks of not being breastfed are less often reported, but the advantages to mothers themselves from breastfeeding and the disadvantages from not doing so are mentioned even less often. Women need to be content and well to be up to the job of mothering. When they are deciding how to feed their babies, mothers should be entitled to good information, which should include how it affects them, free from misleading commercial promotion.

Breastfeeding is what a baby expects and costs nothing. Human milk is tailor made nutrition, changing in composition from hour to hour, in direct response to a baby’s needs, and it strengthens the immature immune system. Formula-fed babies suffer from more illnesses than do breastfed ones and their mothers too are similarly disadvantaged.

Discussion of the emotional pluses, as well as physical benefits, for the breastfeeding mother tends to focus primarily on the baby, and the ease of bonding with a more settled child. The reporting of any maternal “selfish” benefits is often limited to the perk of speedier weight loss postpartum for the nursing mother.

The “breast is best” message, portraying breastfeeding as the gold standard, the manifestation of perfection, leads some mothers to think it is an unattainable goal rather than the biological norm, i.e. something that is simply meant to happen. That image also makes breastfeeding appear to be all give and no take, which is far from the truth. Like all mammals, humans are designed to breastfeed and not doing so may have far-reaching consequences, not only for babies but their mothers too.

Who tells mothers?

Following birth, immediate skin-to-skin contact and the baby’s suckling release oxytocin from the mother’s pituitary gland. This hormone signals the breasts to let down milk to the baby and simultaneously produces contractions in the uterus to expel the placenta naturally, helping prevent hemorrhage, and promoting uterine involution. What does this mean with regard to a mother’s choice?

Bleeding

When she has just given birth, if she chooses not to breastfeed, a mother will be at risk of losing more blood and her womb will return to its normal size more slowly.

As long as a mother breastfeeds without substituting formula, food, or pacifiers for feedings, the return of her menstrual periods is delayed. Why do few people tell women that? As natural family planning for the first six months, breastfeeding according to these criteria is considered up to 99 percent effective when used correctly (Kennedy & Visness, 1992). Lactational amenorrhea is variable, with some women reporting their first postpartum menses as late as 42 months. I enjoyed 24 months with no periods following the birth of each of my three children. That in itself was worth the effort expended on breastfeeding!

Natural child spacing ensures both the optimal survival of each child and its mother’s physical recovery between pregnancies. It gives a mother precious time to devote to each new baby. In contrast, the formula-feeding mother requires contraception within six weeks of the birth.

The amount of iron a mother’s body uses in milk production is much less than the amount she would lose from menstrual bleeding, increasing the risk of anemia for the mother who does not breastfeed.

Heart attack and stroke

Mothers who breastfeed may reduce their risk of having a heart attack or stroke later in life (Peters, et al., 2017). After adjusting the results for other risk factors, including smoking, high blood pressure and physical activity, they found mothers who breastfed their babies had a 9 percent lower risk of heart disease and an 8 percent lower risk of stroke than mothers who never breastfed. The longer each woman breastfed her baby, the more their risk of cardiovascular disease appeared to reduce. Each additional 6 months of breastfeeding per baby was linked to a 4 percent lower risk of heart disease and a 3 percent lower risk of stroke.

And among mothers who breastfed their babies for two years or more, heart disease risk was 18 percent lower and stroke risk was 17 percent lower than among mothers who never breastfed.

NEW: The more children a woman breastfeeds and the longer the duration of breastfeeding have been associated with a lower risk of hypertension in postmenopausal women. Obesity and insulin resistance moderated the breastfeeding-hypertension association (Sangshin Park & Nam-Kyong Choi, 2018).

March, 2018: Six Months of Breastfeeding Reduces Mothers’ Risk of Heart Disease 

Breast cancer

In 2007, the American Institute for Cancer Research released the largest review of research into lifestyle and breast cancer that had ever been conducted, which reinforced previous findings that women can reduce their risk by maintaining a healthy weight, being physically active, drinking less alcohol, and breastfeeding their children. The media reports of the findings placed little emphasis on the connection with breastfeeding.

In May 2017, the Continuous Update Project (CUP) published a report as part of the ongoing program analysing the global research. It updates the breast cancer section of the 2007 Second Expert Report and the 2010 CUP Breast Cancer Report. The CUP is led and managed by World Cancer Research Fund International in partnership with the American Institute for Cancer Research. The media reporting of the findings, this time, focused largely on the association between alcohol and breast cancer and again little mention has been made of breastfeeding.

The CUP report reviewed evidence from 119 studies from around the world. The studies examined more than 12 million women and over 260,000 cases of breast cancer. The dose response meta-analysis showed a significant decreased risk with increasing duration of breastfeeding studies that included pre- and postmenopausal breast cancers, and no heterogeneity was observed. Out of 18 studies analyzed, 13 found the risk of breast cancer dropped 2 percent for every 5 months a woman breastfed.

The mechanisms through which breastfeeding may influence cancer risk are several. Lactation induces a unique hormonal pattern along with an associated period of amenorrhea and infertility. This decreases lifetime exposure to menstrual cycles and therefore alters hormone levels, which can influence cancer risk. Increased levels of sex steroids are strongly associated with risk of postmenopausal breast cancers (The Endogenous Hormones and Breast Cancer Collaborative Group, 2002). Perhaps lactation also induces epigenetic changes that exert a lasting impact on risk of cancer. In addition, the strong exfoliation of breast tissue during lactation, and the massive epithelial apoptosis (cell death) at the end of lactation, could decrease risk by elimination of cells with potential DNA damage.

In an eight-year study of over 60,000 women who had given birth, having breastfed at all provided up to a 59 percent reduction in the risk of developing pre-menopausal breast cancer in women with a family history of the disease (Stuebe, Willett, Xue, & Michels 2009). That means, for women with a family history of breast cancer, breastfeeding can reduce the odds of developing pre-menopausal breast cancer by more than half.

The cumulative protective effect of lactation is one explanation for why developed countries, whose mothers breastfeed for shorter durations (or not at all) and have fewer children in their lifetimes, have higher rates of breast cancer.

Islami et al., 2015 showed a protective effect of ever breastfeeding against hormone receptor-negative breast cancers, which are more common in younger women and generally have a poorer prognosis than other subtypes of breast cancer.

Lööf-Johanson, Brudin, Sundquist, & Rudebeck (2016) concluded that a total breastfeeding history >6 months and pregnancy are associated with both greater overall and breast cancer-specific survival for women diagnosed with breast cancer, having lived long enough for other causes of death to contribute substantially to mortality.

Breastfeeding also lowers a mother’s risk of developing other cancers including ovarian, uterine, and endometrial (Cramer, 2012). An international study, led by Australian researchers at the QIMR Berghofer Medical Research Institute (May 2017), found women who breastfed at least one child for 9 months had an 11 percent lower risk of developing uterine cancer compared to those who had never breastfed. The researchers examined data from more than 26,000 mothers and found a woman who breastfed 2 children for 9 months each had around a 22 per cent lower risk of uterine cancer than a woman who had never breastfed her children.

If a mother does not breastfeed, it follows that she increases her risk of cancer.

Fat

Production of milk is an active metabolic process, requiring the use of calories. Like any biological process, this varies from person to person, but if a mother exercises and eats a healthy diet, nature intends her to lose the extra weight she puts on during pregnancy over the few years it intends her baby to get breast milk.

The reduction in BMI associated with just six months’ breastfeeding could importantly reduce women’s risk of obesity-related disease and their costs as they age (Bobrow, Quigley, Green, Reeves, & Bera, 2012).

The findings of one study suggest that women who breastfeed have reduced amounts of abdominal fat, even decades later. Middle-aged women who consistently breastfed their children had waist circumferences that were an average of 2.6 inches smaller than women who had never breastfed (McClure & Goldberg, 2010). Since the belly is the least healthy place for women to store fat, this is a compelling incentive to breastfeed.

Breast shape, size, and looks are altered by pregnancy and age, not by breastfeeding. An entertaining book dispelling this myth is Saggy Boobs by Valerie Finigan, Pinter & Martin 2009.

A mother who does not breastfeed is at a greater risk of carrying more weight than is good for her.

Diabetes

Not breastfeeding may have persistent unfavorable effects on women’s cardiometabolic health, which is however good news for breastfeeding diabetics (Gunderson et al., 2009) and an important consideration for all, since heart attacks are the leading cause of death in women. The study, however, puts it the other way round, i.e. that breastfeeding may have favorable effects. When you look at nearly all the research studies, it is the benefits provided by breastfeeding that are recorded rather than the risks mothers run by not breastfeeding. This is perhaps something that researchers should be aware of,  because they start from the assumption that formula-feeding is the norm, which, of course, from a biological perspective it should not be.

When you look at nearly all the research studies, it is the benefits provided by breastfeeding that are recorded rather than the risks mothers run by not breastfeeding

Breastfeeding substantially reduces the risk of type 2 diabetes in later life. (Liu, Jorm & Banks, 2010).

Gunderson (2014) evaluated nearly 1000 mothers from diverse backgrounds who had developed gestational diabetes during their pregnancies and monitored them closely for two years after the birth. Nearly 12 percent had gone on to develop type 2 diabetes. Those who breastfed for more than ten months cut their risk of diabetes diagnosis by almost 60 percent in the 2 years they were followed. Of the women who only breastfed and used no formula for the first 2 months of the baby’s life, 8 percent developed diabetes, compared with 18 percent of the mothers who did not breastfeed and only used formula.

NEW: Gunderson et al., (2018) in an observational 30-year study among young white and black women found that increasing lactation duration was associated with a strong, graded 25 to 47 percent relative reduction in the incidence of diabetes even after accounting for prepregnancy biochemical measures, clinical and demographic risk factors, gestational diabetes, lifestyle behaviors, and weight gain that prior studies did not address.

Bones

Calcium is necessary in the production of milk. Because women lose calcium while lactating, many assume an increased risk of osteoporosis for women who breastfed. This is controversial.

Wiklund et al., (2011) found that lactation is associated with greater maternal bone size and bone strength later in life. One important question that remains to be answered is whether greater maternal bone size and bone strength are also associated with a reduced risk of bone fractures in the long run.

A review by Salari & Abdollahi (2014) shows that despite controversial results, pregnancy may have protective effect on bone health especially if followed by lactation.

Women who had breastfed for 13 months or longer were half as likely to develop rheumatoid arthritis as those who had never breastfed. Those who breastfed for between one and 12 months had a 25 percent decreased risk (Pikwer, Bergstrom, Nilsson, Jacobsson, Berglund & Turesson 2009).

Yazici et al., (2011) found that changes of bone metabolism during lactation had no effect on postmenopausal bone mineral density. Consequently, it could be suggested that long breastfeeding duration is not a risk factor for low bone mass later in life.

Baby blues

As someone with an anxious frame of mind, my years breastfeeding stand out for me as the calmest, in spite of the challenges of parenting young children. Breastfeeding is pleasurable: it’s a great biological design. “Breastfeeding does not deplete mothers, nor does it cause depression,” says health psychologist Kathleen Kendall-Tackett.

Breastfeeding mothers exhibit a less intense response to adrenaline (Altemus, Deuster, Galliven, Carter, & Gold, 1995). Sitting or lying down often to nurse compels a mother to relax. With an increase in maternal levels of natural opiates during lactation, the release of oxytocin (the hormone of love) followed by a release of prolactin (the milk-making and calming hormone), there comes a letting go, followed by a serenity that encourages her to slow down to adopt this new pace of life, to cope, and enjoy mothering. All this is quite apart from the personal satisfaction and peace of mind a mother may have from doing what puts her child at least risk.

Breastfeeding might well protect against negative moods and stress. Breastfeeding mothers had more positive moods, reported more positive events, and perceived less stress than formula-feeders (Groër, 2005).

To make her life easier, a mother will often have her baby in her arms and babies who are carried cry and fuss less (Hunziker & Barr, 1986).

Exclusively breastfeeding mothers appear to get more sleep than their mixed- and exclusively formula-feeding counterparts (Kendall-Tackett, Cong, & Hale, 2011). Maintenance of breastfeeding, as well as deep restorative sleep stages, may be greatly compromised for new mothers who cope with infant feedings by supplementing in an effort to get more sleep. Advising women to avoid nighttime breastfeeding to lessen their risk of depression is unwise. In fact, if women follow this advice, it may actually increase their risk of depression.

A mother who feels that breastfeeding is the only thing that is working well in her life does well to continue if she chooses to take medication to treat her depression. Most antidepressants prescribed nowadays are compatible with breastfeeding, though not all those prescribing them are aware of this.

Alzheimer’s

Mothers who breastfeed may have a decreased risk of Alzheimer’s disease in later life (Fox, Berzuini, & Knapp, 2013). The link may be down to breastfeeding’s action in restoring insulin sensitivity and glucose tolerance, which is significantly reduced during pregnancy. More research is needed to investigate the relationship between breastfeeding physiology and cognitive health.

Multiple sclerosis

Mothers who breastfeed for a total of at least 15 months over one or more pregnancies may be less likely to develop multiple sclerosis (MS) compared with those who don’t breastfeed at all or do so for up to four months, according to a study published in July (Langer-Gould, et al., 2017). Women with MS have significantly fewer relapses, or attacks, during pregnancy or while they are breastfeeding exclusively.

Endometriosis

Endometriosis is a chronic and poorly understood disorder in which uterine tissue grows outside the uterus. It can cause severe pain and excessive bleeding during menstruation, among other problems. Farland et al., (2017) studied 72,394 women who had had one or more pregnancies. There were 3,296 diagnoses of endometriosis among them. Compared with women who breastfed for less than a month per pregnancy, those who breastfed for 12 months or more had a 32 percent reduced risk for endometriosis. For each additional 3 months of nursing, they reduced their risk by 8 percent. This association was partially, but not fully, influenced by postpartum amenorrhea, suggesting that breastfeeding could influence the risk of endometriosis both through amenorrhea and other mechanisms. Given the chronic and incurable nature of endometriosis, breastfeeding should be further investigated as an important modifiable behavior to mitigate risk for pregnant women.

The above list of advantages and disadvantages is not comprehensive. Talk to any mother who has breastfed her child comfortably and she will tell you particular reasons that made the experience especially important for her.

From a mother’s perspective, what all this illustrates is that breastfeeding is a precious gift she gives to herself as well as to her baby and that mothers who do not breastfeed are not reaping those same rewards.

References

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