In this study, we estimated the prevalence of lactational mastitis and its associated factors in representative samples of breastfeeding women in Ethiopia, Kenya, Malawi, and Tanzania. It aimed to address the dearth of evidence on lactational mastitis in LMICs, particularly in Sub-Saharan Africa.
Analysis showed a pooled prevalence of mastitis among breastfeeding women of 6.7%, with the lowest prevalence noted in Ethiopia (3.1%) and the highest in Kenya (12.0%). More than half of women who experienced mastitis reported multiple episodes. Our estimates are somewhat lower than those reported in previous studies conducted in other settings. For instance, a small prospective cohort study of nulliparous women in Australia reported an incidence of lactational mastitis of 20%[16]. Another small cohort study conducted in Iran found that about 19% of women experienced mastitis[17]. In contrast, in China, a lower proportion of breastfeeding women reported experiencing at least one episode of mastitis (6.3%) [18]. Our pooled prevalence estimate of lactational mastitis is also higher than incidences noted in HIV-infected and uninfected women in South Africa (1% and 0.5%, respectively)[3], but closer to what has been observed in Nepal (8.0%)[19]. The prevalence we identified in Kenya is similar to that noted in a cross-sectional assessment of Ghanaian women at a breast care center (11.8%)[20].
Several reasons can explain the differences between our findings and those observed in other countries. First, there are considerable differences in the definition and measurement of mastitis across studies. For instance, some studies have considered diagnosis by health care providers [18] or the incidence of breast and systemic symptoms within a specific time frame [16], while our study was based on self-reported symptoms of mastitis during up to two years preceding participation in the household surveys. A recent systematic review and meta-analysis demonstrated substantial variability in the definitions of mastitis used in studies, but also in the population of focus (i.e., general population versus hospital-based population) [2]. Additionally, prospective cohort studies can provide more accurate measures of mastitis incidence. As such, our study, which estimated self-reported prevalence retrospectively, may be underestimating the true frequency of lactational mastitis in the four countries. Finally, differences between the countries considered in this study and other settings may be due to variabilities in maternal gut bacteria, thus leading to distinct milk microbiome, and differences in breastfeeding practices[2].
An important result of our analysis is that 17.0% of women who indicated experiencing mastitis stopped breastfeeding their infants because of mastitis-related symptoms. Continued breastfeeding despite mastitis symptoms has been observed in other settings, as it represents one way to alleviate symptoms and prevent the development of other breast complications[21]. Another explanation is that the lack of access to affordable and safe alternatives to breast milk in SSA may result in women preferring or being advised to continue breastfeeding[21]. Further quantitative and qualitative studies into the beliefs, attitudes, and practices of women experiencing mastitis and other clinical issues related to mastitis will be important to understand the enabling factors supporting continued breastfeeding.
Breastfeeding women who had some education and delivered by c-section had higher odds of reporting experiencing mastitis. These results mirror those found in other studies [19, 22]. Women who have some education may be working in formal settings preventing them from establishing and maintaining regular feeding practices to decrease the risk of milk stasis. There is also a possibility that women with higher levels of education were more likely to have understood the survey questions and therefore more likely to report experiencing mastitis symptoms.
The link between c-section and mastitis observed in this study is consistent with findings of a prospective cohort study conducted in Nepal which reported that women who gave birth by c-section were at higher risk of mastitis[19]. A potential explanation raised by the authors is that c-section is associated with delayed initiation of breastfeeding and therefore increased risk of milk stasis, a major risk factor for mastitis[19]. Other studies have also identified that, compared to women who had a vaginal birth, women who delivered by c-section have a higher proportion of breastfeeding difficulties[23].
The relationship of mastitis and household wealth quantile is interesting to note, as we expected wealth and education to be highly correlated and thus related to lactational mastitis in a similar way. Very few studies have looked at changes in the frequency of mastitis by a measure of socioeconomic status (SES), such as household wealth. However, Vogel et al. found that high SES was associated with higher odds of reported mastitis (OR = 1.13) [24], which is in accordance with the relationship we observed between education and mastitis. Another study conducted in Australia highlighted that women from wealthier households had lower odds of lactational mastitis[25]. There are possible pathways through which high SES could lead to a reduced likelihood of lactational mastitis. For instance, compared to women from poorer households, those from richer households may have greater access to health services and supportive counseling on breastfeeding and information to prevent mastitis. An alternative explanation is that women from wealthier households may have access to water for handwashing, thus limiting the transfer of bacteria to the breast during the breastfeeding process. Future studies are needed to elucidate the pathways through which SES could influence the risk of lactational mastitis.
While the confidence intervals for ORs for the relationships of maternal age and prelacteal feeding practices with mastitis were wide in our study, the direction of the ORs suggests that they may be important factors associated with mastitis. These potential determinants of mastitis should be further investigated in future studies with larger sample sizes. The available literature supports findings that lactational mastitis is higher in young women and women who did not practice prelacteal feedings than in their counterparts who are older and who did not engage in prelacteal feeding respectively[4, 19].
Strengths and Limitations
The main strength of this study is that we used large representative household surveys across four SSA countries to address the scarcity of information on the prevalence of lactational mastitis and related breastfeeding discontinuation in these settings. We also explored associations that have not been considered in the past in those countries. In addition, from the four countries, we had high participation rates (more than 95% in each country), thus limiting the risks of non-response bias.
Still, there are important limitations to be considered. First, the random walk approach used in Malawi may affect the representativeness of the data. Also, as our surveys took place in specific districts, counties, and zones within the four countries, there remains a possibility that our results would only apply to those specific areas. Another limitation is that the associations are based on cross-sectional data; we, therefore, cannot interpret any of the relationships presented here as causal. There are chances of reverse causality. For instance, mastitis could explain why women do not exclusively breastfeed during the first six months after birth. Still, for some explanatory variables such as c-section and prelacteal feeding, we can reasonably conclude that they occurred before mastitis. Another limitation is that all the variables included in this study were based on self-report, hence increasing the chances of recall bias and misclassification. Although we do not think that women are likely to underreport experiencing mastitis, to appraise potential bias in reporting, we compared mastitis among women < 6 months postpartum and those 6–24 months postpartum. We found that the odds of ever experiencing mastitis were higher among women 6–24 months, consistently with the longer time at risk of the condition. We also attempted to overcome the risk of recall bias by restricting our sensitivity analyses to women less than six-month postpartum. Some of the variables considered in this study may have also been underestimated or overestimated because of social desirability bias or challenges understanding the questions. We attempted to ease the comprehension of the questions by administering the surveys in local languages and training the data collectors on the technical interpretation of survey terms. Also, the majority of the questions (except from the mastitis questions) were framed based on standardized DHS and Multiple Indicator Cluster Survey (MICS) questionnaires.
Because of sample size limitations, we could not conduct country-specific logistic regression analyses. Similarly, while the directions of the ORs from the sensitivity analyses were aligned to those reported for the full sample, the sample size limited our ability to get precise ORs. Future studies will be needed to further document the risk factors of lactational mastitis early in the postpartum period. Finally, our surveys did not include information on other key factors such as breast characteristics and history of mastitis. More studies should explore additional variables capturing potential anatomical, socio-demographic, individual and health facility factors related to the occurrence and experience of lactational mastitis.