Effect of maternal country of birth on breastfeeding practices: results from Portuguese GXXI birth cohort

Breastfeeding is a universally accepted means of optimal nutrition that promotes infant survival, growth and development [1, 2]. World Health Organization (WHO) recommends that infants be exclusively breastfed for the first 6 months of life with continued breastfeeding up to 2 years of age or beyond with adequate complementary feeds [3]. Breastfeeding is cost effective with life course benefits for mother and child [4]. Fundamentally, it has been established to have a positive effect on intelligence, to be protective against childhood infections and obesity, as well as decreasing risk of some non-communicable diseases in adulthood [4, 5].

Infant feeding practices are determined by sociodemographic factors including maternal country of birth [1]. However, this association is typified by mixed findings [1, 6‐9]. There are results indicating that immigrants with high income are more likely to initiate and breastfeed for longer duration than native born mothers [1, 8, 9]. While in other studies lesser or comparable initiation and duration rates were observed irrespective of maternal country of birth [6, 7]. Although the association is not homogenous for all settings, “healthy immigrant effect” could be considered the basis for the disparity of breastfeeding behaviour in migrant and native born mothers [10]. Comparing breastfeeding duration between emigrants and mothers in their home country also suggests a “healthy migrant effect” because of the better indicators in the emigrants [11].

“Healthy immigrant effect” describes immigrants as having better health outcomes compared with native-born and non-migrant populations in countries of origin [10]. The relationship between the maternal country of birth and perinatal outcomes has been well documented, but few regarding breastfeeding [4, 12, 13]. Even fewer studies addressed the effect of duration of residence by migrants in the host country on breastfeeding in European settings [14, 15]. In international terms, the share of immigrants particularly from contemporary conflict zones in total population in Portugal is relatively low. The national statistics shows that the immigration flows into the country, which accelerated in the last three decades is mainly linked with employment opportunities, and females constituted a slightly greater proportion of the immigrant population [16, 17]. Therefore, this study investigated breastfeeding initiation and duration in a birth cohort comparing Portuguese and migrant mothers. Additionally, we examined the effect of time since migration to Portugal on breastfeeding practices. We hypothesized that migrant mothers would have greater proportions of breastfeeding initiation and longer duration.

Participants consisted of native Portuguese (6831, 96.7%), other Europeans (61, 0.9%), South Americans (106, 1.5%) and Africans (67, 0.9%) (Table 1). There is variation in some observed characteristics of foreign and native born mothers. The majority (80.2%) of South Americans had resided for ≤5 years in Portugal as compared to 39.3 and 29.9% of other Europeans and Africans. The proportion of migrants that arrived in Portugal after ≥18 years of age was: other Europeans (93.4%), South Americans (97.2%) and Africans (70.1%). Mothers aged ≥35 years were around one third among Africans (31.3%) but lower percentages for South Americans (14.2%), other Europeans (8.2%) and native Portuguese (17.1%). Only 21.4% of Portuguese mothers and from 17.9 to 39.3% of migrants were tertiary educated. The proportion of households earning 1000 euros or less per month were 38.4% for native Portuguese, 24.5% for other Europeans, 52.3% for South Americans and 42.1% for Africans. The proportion of primiparous mothers was 57.5% (native Portuguese), 73.8% (other Europeans), 62.5% (South Americans) and 48.8% (Africans). More than 80% of mothers attended > 6 prenatal visits irrespective of their country of birth. Caesarean section rates were 35.9% (native Portuguese), 33.3% (other Europeans), 51.9% (South Americans) and 37.9% (Africans). Low birthweight prevalence was 7.1% (native Portuguese), 3.3% (other Europeans), 3.8% (South Americans) and 4.5% (Africans). Preterm birth and NICU admission proportions were respectively 7.2 and 8.7% for native Portuguese, 6.6 and 19.3% for other Europeans, 4.7 and 4.0% for South Americans, 9.0 and 6.1% for Africans.

This study assessed the effect of maternal country of birth on breastfeeding practices among mothers of a birth cohort recruited in Portugal. We observed that the native Portuguese and migrant mothers were similar in their marital status, occupation, number of prenatal visits and birth outcomes. However, there was variation in the distribution of maternal age, education, household income, parity and caesarean section. In our sampled population, the migrants had a higher proportion of tertiary educated mothers. A third of the African born mothers were ≥ 35 years, while the other migrant groups had a lower proportion of this age category compared with the Portuguese. Nevertheless, the proportion of those that initiated any and exclusive breastfeeding were similar for foreign and native born mothers. However, migrants have longer duration of any and exclusive breastfeeding. Furthermore, the length of residence in Portugal by migrant mothers does not negatively impact on the breastfeeding duration.

Breastfeeding could be dependent on the social context of study country or setting. In western developed societies there are evolving social and lifestyle factors that modify breastfeeding practices over time [23]. Substantial proportions of mothers participating in this study were employed and discontinue exclusive breastfeeding before the recommended 6 months duration. This is because maternal employment is known to significantly affect breastfeeding duration [24]. We observed a decline of exclusive breastfeeding at 4 months for both maternal categories, which coincides with the expiration of 4 months of full paid maternity leave according to Portuguese law. [25]

Our findings showed that migrant mothers irrespective of their length of residence in Portugal breastfed (any breastfeeding or exclusive breastfeeding) for longer periods than their native peers, which is contrary to the observation of some studies [15, 26, 27]. Specifically, the African-born women averagely had lengthier period of residence in Portugal but breastfeed for longer duration compared with other migrant mothers. This negates the notion that acculturating to host country could negatively influence migrant mother’s breastfeeding practices, especially those coming from settings with higher breastfeeding rates than Western nations [26]. Our observation is not unusual because acculturation has been reported as not having an influence on breastfeeding for particular migrant groups [7, 28]. Basically, certain traditional beliefs facilitate positive breastfeeding practices that persist for longer period especially in migrants from cultural backgrounds, which western breastfeeding practices was unknown or perceived as unacceptable [29]. On the contrary, it has been shown that post migration, immigrant breastfeeding rates tends to converge towards native born rates of breastfeeding as length of residence in host country increases [15].

An important public health implication of this study is that the duration of any breastfeeding and exclusive breastfeeding were below the WHO recommendations in native Portuguese and migrant mothers. Thus, we recommend intensive breastfeeding promotion for all maternal categories especially for the employed to whom adequate conditions to continue breastfeeding should be provided. Breastfeeding education during prenatal and postnatal care should be emphasized because of its effectiveness at enhancing breastfeeding initiation and duration [30]. In Portugal, there is universal healthcare for women irrespective of immigration status. This is relevant for immigrants because migration isolates women but health professionals could serve as a major source of information on breastfeeding [31]. More so for recently arrived migrant mothers arriving at a time characterized by multiple challenges to breastfeeding practices in contemporary European context. Finally, future research can improve the understanding of the exact role of maternal country of birth in breastfeeding. It is fundamental to explore acculturation pathway to explain healthy migrant effects by comparing breastfeeding practices in source countries with that of first and second generation migrant as well as native-born mothers.

The study has shown that maternal country of birth influences breastfeeding duration but not its initation among mothers of Generation XXI birth cohort. Migrant mothers have longer duration of exclusive or any breastfeeding, which was not changed by length of residence in Portugal. The duration of breastfeeding is below recommended duration in both native and foreign-born mothers. We recommend intensive promotion of breastfeeding for all categories of mothers especially the employed to whom adequate condition to continue breastfeeding should be provided.