Is There an Association Between Breast Hypoplasia and Breastfeeding Outcomes? A Systematic Review

Maternal Breast Growth and Body Mass Index Are Associated with Low Milk Production in Women

BACKGROUND

Maternal breast volume is determined by the quantity of glandular and adipose tissue, and it undergoes significant changes during pregnancy. These changes are intricately linked to the development of glandular tissue, which most likely reflects lactation capacity. Evidence indicates that women with overweight or obesity exhibit larger breast volume compared to those with a normal body mass index (BMI), emphasizing the close relationship between breast volume and maternal adiposity. Hence, we aim to investigate breast volume growth and maternal BMI as potential risk factors for low milk production.

METHODS

Lactating women (n = 609) from the Perth metropolitan area in Western Australia between 2011 and 2023 were included in the analysis. Twenty-four-hour milk production measurements were conducted using the test weighing method, and milk removal frequencies were recorded. Mothers completed questionnaires regarding demographic, obstetric and infant details. Linear and logistic regression models were used to determine maternal and infant factors associated with milk production.

RESULTS

Here we show that increasing maternal age and BMI are associated with low milk production. Moreover, larger pre-pregnancy breast volume and breast growth are associated with both higher BMI and milk production.

CONCLUSIONS

Women who are older, have an obese BMI and who have minimal pre-pregnancy breast volume and breast growth should be provided with antenatal screening and breastfeeding support as they are more likely to experience low milk production.

Having Enough Milk to Sustain a Lactation Journey: A Call to Action

The rates of human milk feeding are suboptimal worldwide. Recommendations for healthy, term mother-infant dyads include early breastfeeding initiation, frequent skin-to-skin contact, and frequent breastfeeding. The normal physiology of lactation can be affected by prenatal factors such as diabetes, obesity, and excessive gestational weight gain. Furthermore, birth-related factors such as early-term gestation, stressful labor, unscheduled cesarean birth, and postpartum hemorrhage can additionally disrupt recommended practices such as early initiation of breastfeeding and skin-to-skin contact. Given that the first 2 to 3 days postpartum are critical to achieving timely secretory activation and establishing an adequate volume of milk, a proactive approach to care can include building awareness of risk factors and development of protocols for the effective early initiation of lactation.

Maternal metabolic conditions as predictors of breastfeeding outcomes: Insights from an Australian cohort study

INTRODUCTION

Breastfeeding represents an important opportunity to optimize health outcomes for both mother and infant, particularly in the context of maternal metabolic conditions such as diabetes and polycystic ovary syndrome. However, evidence suggests that women affected by these conditions breastfeed at reduced rates and durations. Our aim was to use the large, prospective, community-based Australian Longitudinal Study on Women's Health (ALSWH) to conduct an in-depth exploratory analysis of breastfeeding outcomes in Australian women affected by key maternal metabolic conditions.

MATERIAL AND METHODS

Data from 12 920 pregnancies to 5605 women from the 1973-1978 birth cohort of the ALSWH were examined. Univariable and multivariable regression using generalized estimating equation models were applied to assess breastfeeding initiation and duration (outcome measures) in relation to key self-reported maternal metabolic diagnoses (pre-gestational type 1 and type 2 diabetes, gestational diabetes, and polycystic ovary syndrome; main explanatory variables). Key sociodemographic and clinical covariates were also considered.

RESULTS

Results showed no significant association between specific maternal metabolic diagnoses (pre-gestational or gestational diabetes, or polycystic ovary syndrome) and breastfeeding outcomes. However, maternal body mass index emerged as a key predictor of suboptimal breastfeeding outcomes. Pregnancies affected by maternal obesity were associated with a 2.1-fold increase in the odds of not initiating breastfeeding, after adjusting for other key variables (95% CI 1.67 to 2.60, p < 0.01). Maternal overweight and obesity were, respectively, associated with an adjusted 1.4-fold (95% CI 1.20 to 1.55, p < 0.01) and 1.8-fold increase (95% CI 1.60 to 2.10, p < 0.01) in the odds of a breastfeeding duration less than 6 months.

CONCLUSIONS

Maternal obesity, rather than any specific maternal metabolic condition, appears to be a key predictor of breastfeeding outcomes in Australian women.

Breast hypoplasia markers among women who report insufficient milk production: A retrospective online survey

OBJECTIVES

To estimate the proportions of anatomical breast characteristics suggestive of breast hypoplasia among breastfeeding women self-reporting low milk supply. We also explored breast hypoplasia risk factors.

DESIGN

Online survey conducted between October 2021 and January 2022.

SETTING

Five low milk supply Facebook groups.

PARTICIPANTS

487 women reporting low milk supply with their first child born ≥ 37 weeks gestation within 5 years of participation in this study, and residing in the USA, Australia or the UK. We present data on the primary outcome ('breast type') for 399 women. Women were excluded if the dyad was separated for more than 24 hours during the hospital stay, or if the mother reported removing milk less than 6 times per day from each breast on most days before being aware of having insufficient milk production.

PRIMARY AND SECONDARY OUTCOME MEASURES

The proportions of proposed breast hypoplasia markers including atypical breast type, widely spaced breasts, breast asymmetry, stretch marks on the breast and lack of pregnancy breast growth. We also estimated the odds of having breast hypoplasia markers in at-risk groups compared to reference groups, adjusting for covariates.

RESULTS

Approximately 68% reported at least one atypical breast (270/399; 95% CI: 62.9%, 72.1%). Around 47% reported widely spaced breasts (212/449; 95% CI: 42.7%, 52.7%), 72% a lack of pregnancy breast growth (322/449; 95% CI: 68.3%, 77.4%), and 76% stretch marks on the breast (191/250; 95% CI: 70.7%, 81.3%). Multiple logistic regression analyses identified being overweight during pubertal years as a risk factor for atypical breast type and lack of pregnancy breast growth.

CONCLUSIONS

Participants in low milk supply Facebook groups reported high rates of breast hypoplasia markers. Being overweight during adolescence was a risk factor for breast hypoplasia markers. These findings should be confirmed in well-conducted large cohort studies to determine the strongest combination of hypoplasia markers in predicting low supply.

Causes of Low Milk Supply: The Roles of Estrogens, Progesterone, and Related External Factors

Low milk supply (LMS) poses a significant challenge to exclusive and continued breastfeeding, affecting ∼10% to 15% of mothers. Milk production is intricately regulated by both endocrine and autocrine control mechanisms, with estrogens and progesterone playing pivotal roles in this process. In addition to endogenously produced hormones, external substances capable of interfering with normal hormonal actions, including phytoestrogens, mycoestrogens, synthetic estrogens, and hormonal contraceptives, can influence milk production. The effects of these extrinsic hormones on milk production may vary based on maternal body mass index. This comprehensive review examines the multifaceted causes of LMS, focusing on the involvement of estrogens, progesterone, and related external factors in milk production. Furthermore, it investigates the interplay between hormonal factors and obesity, aiming to elucidate the endocrine mechanisms underlying obesity-associated LMS. Insights from this review provide valuable perspectives for developing interventions to improve milk production and address the challenges associated with LMS.

Measures of Maternal Metabolic Health as Predictors of Severely Low Milk Production

Background: A comprehensive approach to breastfeeding support requires elucidation of how metabolic health influences milk production. Objective: We compared metabolic health indicators in women with severely low milk output versus those with moderate/normal milk output using a case-control study design, with nested and external control groups. Design: Cases and nested controls were derived from women screened for a low milk supply trial, with cases defined as severely low milk output (<300 mL/24 hours), and nested controls defined as moderate/normal milk output (>300 mL/24 hours). In addition, we included an external control group of exclusively breastfeeding women. All were enrolled at 2-10 weeks postdelivery of a healthy term infant. Milk output and breast emptying frequency were recorded through test-weigh. Metabolic health variables included all components of the metabolic syndrome, homeostatic model assessment of insulin resistance (HOMA-IR), and diagnosis of gestational diabetes mellitus (GDM). Results: Maximum milk output, mL/24 hours, ranged as follows: 30-281 in cases (n = 18), 372-801 in nested controls (n = 12), and 661-915 in external controls (n = 12). Mean breast emptying frequency in cases was not significantly different from nested or external controls. All metabolic syndrome components and HOMA-IR were significantly worse in cases as compared with both nested and external control groups (p < 0.05). There was no significant difference between the nested and external control groups for these variables. GDM prevalence was 39%, 0%, and 8%, across cases, nested control, and external control groups, respectively (chi-square p-value = 0.02). Conclusion: Results from this small case-control study identify class 2+ obesity and poor metabolic health as strong risk factors for severely low milk production. These findings should be further validated in larger prospective cohort studies designed to identify individuals at risk for metabolically driven low milk supply. In addition, clinical and qualitative research studies aimed at improving patient-centered approaches to the management of persistent low milk supply are needed.

Current Resources for Evidence-Based Practice, November 2021

An extensive review of new resources to support the provision of evidence-based care for women and infants. The current column includes a discussion of autonomy and respect in maternity care and commentaries on reviews focused on whether to induce women who present with mild preeclampsia in the late preterm period and the extent to which urinary incontinence symptoms prevent women from participating in exercise. It also includes a brief update about the USPSTF guidelines on screening for gestational diabetes.

Breast Milk Production in Women Who Use Nipple Shields for Persistent Nipple Pain

OBJECTIVE

To examine relationships between nipple pain scores and 24-hour milk production volumes, breastfeeding and pumping frequencies, and breastfeeding duration in women using nipple shields for persistent nipple pain.

DESIGN

Secondary outcome analysis of a prospective cohort study.

SETTING

Research laboratory and participants' homes.

PARTICIPANTS

Twenty-five breastfeeding women (6 ± 4 weeks after birth) who used nipple shields for persistent nipple pain.

METHODS

We conducted a randomized trial to investigate the primary outcome of milk transfer with and without nipple shields among participants with and without nipple pain. Here, we report secondary outcomes of associations between 24-hour milk production, breastfeeding and pumping frequencies, breastfeeding durations, and intake in participants using a nipple shield for nipple pain. Participants completed demographic, health and breastfeeding questionnaires and, at two monitored breastfeeding sessions, completed a pain visual analogue scale and Brief Pain Inventory-Short Form (BPI-SF; total and subscale scores for pain interference with General Activity, Mood, Sleep, and Breastfeeding). Milk production (milliliters per 24 hours), feed volumes, and percentage of available milk removed were calculated from data and milk samples obtained by participants over one 24-hour period and at study visits. Participants logged 24-hour data on a customized research website. We used descriptive statistics as well as simple and multiple linear regression for analyses.

RESULTS

Milk production and feeding duration were not associated with nipple pain scores (visual analogue scale: p = .80, BPI-SF: p = .44). An increase in BPI-SF Breastfeeding subscale score of 1 unit, indicating pain interference with breastfeeding, was associated with a 0.28 decrease in breastfeeding frequency (p = .02) and an 18.8-ml decrease in 24-hour breastfeeding intake (p = .04).

CONCLUSION

Persistent nipple pain was associated with reduced breastfeeding frequency; therefore, continuing professional support is required to ensure adequate milk removal and pain management.

25 Years of Research in Human Lactation: From Discovery to Translation

Researchers have recently called for human lactation research to be conceptualized as a biological framework where maternal and infant factors impacting human milk, in terms of composition, volume and energy content are studied along with relationships to infant growth, development and health. This approach allows for the development of evidence-based interventions that are more likely to support breastfeeding and lactation in pursuit of global breastfeeding goals. Here we summarize the seminal findings of our research programme using a biological systems approach traversing breast anatomy, milk secretion, physiology of milk removal with respect to breastfeeding and expression, milk composition and infant intake, and infant gastric emptying, culminating in the exploration of relationships with infant growth, development of body composition, and health. This approach has allowed the translation of the findings with respect to education, and clinical practice. It also sets a foundation for improved study design for future investigations in human lactation.