Introduction
The offer of the mother's breast to her baby is a biologically and ethically unquestionable
right of both mother and child and is of fundamental importance for the survival and
quality of life of the nursing baby during its first years of life. Today, the benefits
of breastfeeding are considered not to be limited to the duration of the practice,
but to extend until adult life, with repercussions on the long-term quality of life.[1] Many publications are available in the literature about the qualities of breast
milk, its benefits and health repercussions, stimulating the practice of breastfeeding
and supporting campaigns such as the World Week of Breastfeeding. Even though it is
widely known that breastfeeding is an important stage in the reproductive process
of women and that its practice is beneficial for both mother and child, it can be
seen that the information provided during prenatal care, puericulture practices or
public health campaigns is directed at the benefits of breastfeeding for babies, while
mention of all the effects of breastfeeding on the health of the mother is neglected.[2]
Lactation is a differential characteristic of mammals and both the synthesis and secretion
of milk are complex biochemical and neuroendocrine processes that involve the sensitive
terminals of the areole and the nipple and are under hormonal control. Thus, lactation
is the direct and natural result of pregnancy and birth, like an integral part of
reproductive process that benefits both mother and child simultaneously.[3] The interaction of all of these factors will culminate with the production of milk
and will definitely cause changes in the maternal organism by also favoring good physical
and emotional health conditions for the nursing mother extending into her future life.[4]
[5]
Benefits for the Mother
Breastfeeding (BF) seems to be related to good physical and emotional health for the
mother during the puerperium, the lactation period and all her future life. Epidemiological
studies have demonstrated that, compared with women who did not breastfeed, lactating
women reported seeking for medical care less often, a lower frequency of respiratory,
cardiocirculatory and gastrointestinal diseases, as well as fewer symptoms related
to emotional problems.[6]
[7] On this basis, it is possible to emphasize the benefits of breastfeeding for the
lactating mother, as described in [Table 1].
Table 1
Benefits of breastfeeding for the mother's health
|
Immediate
|
Long-term
|
|
Uterine involution
Reduced bleeding
Reduced infection
Lactational amenorrhea
Reduced adiposity and weight
Reduced postpartum depression
Reduced stress and anxiety
Improved body image
|
Reduced:
cancer (breast, ovarian, endometrium)
endometriosis, diabetes, osteoporosis, blood pressure and cardiovascular diseases,
metabolic syndrome, rheumatoid arthritis, Alzheimer disease and multiple sclerosis
|
Early suckling of the areal-mammillary region is one of the most important stimuli
for the production of oxytocin, which is also responsible for uterine contraction,
accelerating the return of the organ to its normal size and reducing the possibility
of the occurrence of postpartum hemorrhage and anemia. High levels of oxytocin can
increase the pain threshold, reducing maternal discomfort and thus contributing to
an increased feeling of love for the baby.[8]
During the lactation period, both progesterone and estrogen are suppressed, with the
occurrence of a period of infertility. While the mother exclusively breastfeeds, her
protection against pregnancy can reach 96% during the first 6 months, thus ensuring
spacing between pregnancies.[9]
[10] To this end, the mother also must not have menstruated and should maintain exclusive
breastfeeding on demand for at least eight times a day. Breastfeeding amenorrhea may
be explained by the inhibition of ovarian activity resulting from high prolactin levels
that lead to inhibition of the gonadotropin hormone and to the interruption of ovulation.[11] It has been estimated that, after the return of the menstrual cycles, the probability
of conception is reduced by 7.4% for each additional month of breastfeeding.[12]
During pregnancy, the body of a woman accumulates a weight of ∼ 3 kg of fat that will
be utilized throughout the first 6 months of breastfeeding, since this process consumes
∼ 2,100 kj/day.[13] On this basis, there will be a more rapid weight loss and the return to pregestational
conditions, with an average monthly reduction of 450 g in the maternal weight,[14] since the released oxytocin also exerts its lipolytic and anorexigenic effects.
A lower body mass index has been detected among mothers who breastfed for a period
of 6–12 months, and those who exclusively breastfed were leaner than those who breastfed
on a partial basis at the end of the first semester of life of the baby.[15]
[16] A study conducted on 314 Mexican mothers revealed that those who exclusively breastfed
for at least 3 months underwent a weight reduction of 4.1 kg compared with those who
did not breastfeed.[17] This observation confirmed the weight reducing capacity of breastfeeding, which
provides a sensation of greater self-esteem and satisfaction with their body image
among lactating women, reducing the possible occurrence of negative emotional factors
that might interfere with milk production and with the practice of breastfeeding.
The birth of a child is usually a source of happiness and pleasure for the family.
However, it is known that ∼ 13% of all puerperae may develop signs and symptoms of
depression within a period of 12 weeks after delivery.[18] Among these women, oxytocin levels have been found to be lower than those of the
other new mothers. Recent studies have shown that oxytocin is a fundamental element
for the stimulation of the bond between mother and child, triggering positive effects
such as vocalization with the baby, looking into its eyes, encouraging touch and caresses.
Mothers have reported that they feel calmer, less aggressive and stressed, in a better
mood and more interested in socializing since the first postpartum days.[19]
Breastfeeding may also act on a mechanism of regulation of daytime cortisol secretion,
with a stable concentration of the hormone possibly reducing the risk of postpartum
depression.[20] Recent studies have demonstrated that women who do not start or maintain BF have
a higher risk of depression during the postpartum preriod.[21]
[22]
[23] There is an inverse association between these phenomena due to the hormonal and
psychological conditions that occur during the first 6–8 weeks of puerperium, since
the lactogenic hormone, oxytocin and prolactin can have anxiolytic effects. This attenuates
stress via neuroendocrine responses, since BF is associated with reduced adrenocorticotrophic
hormone (ACTH) and cortisol levels. Suckling at the maternal breast preceded by skin
to skin contact triggers this process and the longer the duration of this contact,
the lower the cortisol levels.[24]
Several factors can be identified as sources of stress for the puerpera. The physical
task of baby care together with other household activities, the few hours of sleep,
changes in body image, reduced sexual activity and the emotional pressure of trying
to be a good mother and to fulfill all the expectations represent an overload that
is often incompatible with the personality and ability of a women to carry out her
role as a mother. In this situation, BF may act by reducing stress levels because
of its effect on the reduction of cortisol and ACTH levels, consequently reducing
the levels of anxiety.[25] In addition, the strengthening of the mother-child bond is a potent stimulus for
BF maintenance for the longest possible time, closing a virtuous cycle that tends
to benefit both mother and child.
The visceral or intra-abdominal fatty tissue accumulated by a woman during pregnancy
is metabolically more active than the fat deposited in other areas and is related
to cardiocirculatory diseases. However, these deposits can be mobilized during the
lactation period, a process that continues to occur in parallel to BF, reducing the
maternal weight and risk of type 2 diabetes mellitus.[11]
[26]
Mammary neoplasia is the most common gynecological cancer, quite prevalent after the
fourth decade of life, although it can also occur before 40 years of age at frequencies
ranging from 17–36%.[27] Several studies have pointed out the benefits of BF time and its consequent protective
effect against the risk of breast cancer, since the reduction of estrogen levels during
the lactation period reduces the rates of cell proliferation and differentiation.
Tissue exfoliation and epithelial apoptosis at the end of the BF period may contribute
to the reduction of the probability of cells with mutation arising in mammary tissues.[28]
[29]
[30] It is estimated that the risk of breast cancer can be reduced by more than 4% for
each year of BF.[27]
[31]
[32]
[33] According to UNICEF, a 16% increase in the proportion of mothers who breastfeed
for 6 months can reduce the expected prevalence of breast cancer by 1.6% per year.[34]
Cancer of the ovarian epithelium is one of the neoplasias that most affect women and
is usually diagnosed late, with a consequent reduction of survival prognosis. Some
theories have indicated that its causes may be related to cell proliferation and uninterrupted
ovulation traumas. On the other hand, the suppression of gonadotropins (luteinizing
hormone in particular), the low concentration of estrogens and the consequent anovulation
and amenorrhea caused by BF have been considered to be protective factors.[35]
[36] The relative risk of developing ovarian cancer is estimated to be reduced by 2%
for each month of BF.[37] Meta-analysis studies have observed an inverse relationship between these events
and have reported that protection is greater when the time of BF is longer than 10
months.[38]
[39] An analysis of prospective cohort and case-control studies has shown that women
who have never breastfed had a probability of more than 30% of developing cancer of
the ovarian epithelium.[35]
[40] In addition to offering a lower risk of development of ovarian cancer among lactating
women, BF can also increase the life-expectancy of women who have already developed
the disease.[41]
Over the last few years, several epidemiological studies have pointed out some relationship
between cancer of the endometrium and BF and have shown that long periods of BF are
associated with a reduced risk of this type of neoplasia.[42]
[43]
[44]
Endometriosis is a common gynecological disease that affects more than 10% of reproductive-aged
women. Common symptoms include dysmenorrhea, dyspareunia and infertility, and women
who suffer from this chronic condition may experience a wide variety of symptoms,
ranging from mild pain to extremely debilitating disease.[45] According to Farland et al,[45] the duration of total and exclusive BF was significantly associated with a decreased
risk of endometriosis. For every additional 3 months of total BF per pregnancy, women
experienced an 8% lower risk of endometriosis, and women who breastfed for ≥ 36 months
in total across their reproductive lifetime had a 40% reduced risk of endometriosis
compared with women who never breastfed.[46]
The prevalence of type 2 diabetes mellitus has been increasing all over the world
in parallel with the dietary changes, sedentarism and obesity that affect large part
of the population. In this respect, it is opportune to emphasize an important action
of oxytocin, which is a reduction of insulin resistance. Meta-analysis studies have
detected a statistically significant inverse association between BF duration and risk
of type 2 diabetes.[47]
[48] An important review study conducted by Perrine et al[48] detected an inverse and dose-dependent association between BF and type 2 diabetes,
with a reduction of 4–12% of the risk of developing type 2 diabetes with each additional
year of lactation. In contrast, among women who never breastfed, the risk was 50%
higher compared with those who breastfed even for short periods of time ranging from
1–3 months.[49]
[50]
Breastfeeding can contribute to the reduction of the risk of osteoporosis in future
life since it has been demonstrated that lactating women have a bone mass with higher
mineral density. Although the organism of women loses calcium during the BF period
(with the production of 800 ml/day milk a woman can transfer as much as 200 mg calcium
daily, which are recovered after weaning and with the return of menstruation), there
are compensatory mechanisms that increase the intestinal and renal absorption of calcium
and its mobilization from the bones, thus reestablishing bone mineral density.[51]
[52]
[53] During the lactation period there is a 4–7% bone loss, especially in the lumbar
spine and femoral head, which is reversed about 1 year after weaning.[54] The protective effect of this mechanism of bone demineralization is directly proportional
to the duration of BF.[55]
Studies correlating BF with blood pressure have detected lower levels of both systolic
and diastolic pressure among nursing mothers during the BF period, with the observation
of a long-lasting dose–response effect, even though this effect may not persist until
old age.[56]
[57]
[58]
[59]
[60]
[61]
Vascular changes, such as atherosclerotic plaque, increased wall thickness and reduced
arterial lumen, increase the risk of cardiovascular diseases, a fact that has raised
the interest of some investigators in the study of a possible association between
lactation and these vascular changes.[50] Women who breastfeed for long periods of time, 7–12 months after the first delivery,
have a 28% lower risk to develop vascular diseases compared with women who never breastfed.[50]
[62] These findings are also associated with the weight loss and metabolic work to which
the maternal organism is submitted for the daily production of milk, which may persist
even after weaning, contributing to a beneficial effect on the maternal organism.
Women with a total BF time of more than 2 years had a 23% lower probability of developing
coronary diseases than women who never breastfed.[28] An inverse association has also been described between BF duration and atherosclerosis,
after other confounding factors, such as smoking and obesity, are excluded, as determined
by the thickness of carotid artery walls.[62]
Metabolic syndrome (MS) is the result of several changes that include central obesity,
arterial hypertension, dyslipidemia and insulin resistance, which, when associated,
involve severe complications and high mortality rates. It is known that women who
breastfeed for prolonged periods of time have a lower risk of the incidence of MS,
after other factors, such as body mass index and parity, for example, are adjusted.
One of the most important mechanisms involved in this occurrence is the reduced insulin
resistance provided by BF, since a 12% reduction in the risk of MS development has
been observed for each year of lactation.[28]
[63]
[64]
A recent meta-analysis study by Chen et al[65] demonstrated that BF is associated with a lower risk of the onset of rheumatoid
arthritis among nursing women, whether or not the duration of BF is longer than 12
months.
Fox et al[66] studied a cohort of elderly English women and observed that the risk of developing
Alzheimer disease was lower among those who had breastfed, possibly owing to the hormonal
effects of estrogens on brain receptors and of insulin sensitivity triggered by BF.
Multiple sclerosis is a chronic autoimmune disease with a susceptibility and disease
course that are influenced by reproductive factors, affects predominantly women during
their childbearing years and the risk relapses is significantly diminished during
pregnancy and exclusive BF. Among women who had live births, a cumulative duration
of BF for ≥ 15 months was associated with a reduced risk of multiple sclerosis compared
with 0–4 months of breastfeeding.[67]
Conclusion
The benefits of BF for children have been known and reported for a long time, although
the prevalence of this practice and the dissemination of its benefits for the nursing
mother have been found not to be satisfactory in various parts of the world. Despite
that great knowledge, relatively little progress has been made in improving BF outcomes,
such as early initiation and exclusive breastfeeding for 6 months.[3]
Due to its individual and collective importance, the access to BF protection and support
has also been framed as a human right with issues of social justice and equity becoming
superlative.[68] Lactation plays an important role in maternal recovery from pregnancy, and can determine
multiple aspects of maternal health in later life.[69] Therefore, informing pregnant women of the maternal health effects of lactation
would strengthen their intentions to breastfeed. However, it is necessary to respect
the wishes and rights of the mother, who must have autonomy to decide how to feed
her child. The mother, in consultation with other family members, should be the one
who decides how the child is to be fed, and in making this decision, the mother must
be supported and aided by family, employers, health professionals and society.[3] It is also the duty of health professionals to identify the knowledge, previous
experience and social and family context of women since the prenatal period to promote
educational actions directed at the introduction and maintenance of BF when she so
decides.
