Markers of Breast Hypoplasia Among Women Who Report Low Milk Production
by Anne Eglash MD, IBCLC, FABM
Low milk production is the main reason for premature weaning. There are many reasons for low milk production, and we don’t know what % of cases are due to primary low milk production, or the inability of the breasts to produce sufficient milk. Primary low milk production can be due to breast hypoplasia, a history of breast surgery, breast radiation, medications during and/or immediately postpartum, or other health issues such as endocrine pathology.
Breast hypoplasia is a condition where there is low glandular tissue development during pregnancy. Symptoms typically include little breast growth in pregnancy, and low milk production despite frequent and thorough milk removal. Breast anatomic changes are often associated with low glandular tissue, but some people have normal appearing breasts despite having symptoms of low glandular tissue.
The authors for this week investigated the relationship between breast anatomical variations and self-reported low milk production.
The authors evaluated online survey results among 487 participants from several listservs that support people with low milk production. The survey was an extensive questionnaire including questions about anatomic breast characteristics suggestive of low glandular tissue including breast asymmetry, a wide intermammary length (>3.8 cm), stretch marks on the breasts, little/no breast growth during pregnancy, and lack of breast fullness in the first week postpartum.
Most participants were from the USA, with approximately 23% from Australia and 8.8% from the UK, and most were highly educated.
The researchers found that women who described being overweight between ages 8 and 20 were more likely to report signs of breast hypoplasia, including widely spaced breasts and lack of growth during pregnancy, as compared to those who had typical breasts.
This association remained even after adjusting for pre-pregnancy BMI status.
- Approximately 28% of participants reported at least 1 breast being atypical as compared to the other.
- Approximately 72% reported lack of breast growth with their first infant.
- After adjusting for socioeconomic factors, higher BMI was associated with signs of breast hypoplasia.
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Abstract
Objective
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 included 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.
The researchers found that 67% of participants reported at least 1 atypical breast. BMI was not associated with atypical breasts after adjusting for age, country of residence and PCOS status.
The most impressive finding in this study is the association between being overweight during puberty and signs of breast hypoplasia. Most research on the impact of BMI during puberty on breast growth has been done in animals. The researchers mention studies that demonstrated how an obesogenic diet during puberty among mice and rabbits increased the amount of fat in the mammary glands and changed the shape of the alveoli in adulthood. In addition, high pre-pubertal growth rate in bovine has been linked to poorer mammary gland development.
We need much more research on breast hypoplasia and milk production. To start, breast shape and growth are not ideal markers of breast hypoplasia because they are subjective. We need better tools to accurately measure glandular tissue growth during pregnancy, and correlate findings with deficits of milk production.