LBW is associated with increased risks of infant morbidity and mortality, developmental delays, and long-term health issues.A study from Singapore identified an epidemiological paradox: Low birth weight (LBW; <2,500 g) rates were lower among socioeconomically disadvantaged foreign-born mothers than native-born mums.
“Contrary to our expectations, foreign-born immigrant mothers in cross-national families did not have a higher LBW prevalence than native-born mothers. Thus, the large number of female marriage migrants in SG is unlikely to explain SG’s higher LBW prevalence compared with the OECD* average [9.4 percent vs 6.5 percent], as we originally suspected,” the investigators said.
“Surprisingly, despite challenging family dynamics and [more] psychosocial risk factors in cross-national families with foreign-born mothers, these families had the lowest LBW prevalence among the four family types in SG,” they added.
LBW prevalence in cross-national families with a foreign-born mum and a local-born father was 5 percent. Families with two foreign-born parents had an LBW prevalence of 7.3 percent. There were similar rates between native families with both local-born parents (8.5 percent) and cross-national families with a foreign-born father and a local-born mum (8.7 percent). [BMJ Public Health 2026;4:e003456]
The lower LBW rates among foreign- vs native-born mums were consistent irrespective of socioeconomic status (SES) levels (low: 5.13 percent vs 11.87 percent; middle: 4.79 percent vs 7.48 percent; high: 5.07 percent vs 7.08 percent).
Moreover, the lower LBW rates among foreign- vs native mums suggest that prenatal adversity may not be the dominant driver of adverse early child development outcomes observed among children with a foreign-born mum in SG, Taiwan, and Korea. [https://scholarbank.nus.edu.sg/entities/publication/5fecb934-3897-4105-83a6-63f2ef82b8b7, accessed 23 July 2026; Child Care Health Dev 2012;38:595-603; Ethnicity & Health 2013;18:1-17; Crime & Delinquency 2022;68:2395-2421]
After adjusting for demographic and biological characteristics (model 1), cross-national families with a foreign-born mum had 44 percent lower odds of LBW compared with native families (odds ratio [OR], 0.56; p<0.01).
The association became more pronounced in model 2 after adding maternal pregnancy complications and social behaviours during pregnancy to the model 1 covariates (OR, 0.53; p<0.01), more so after further adjusting for family SES in model 3 (OR, 0.47; p<0.01) and for macrolevel measures in model 4 (OR, 0.33; p<0.05).
“This suppression pattern suggests that foreign-born mums had lower LBW prevalence despite their disadvantaged circumstances, further underscoring the paradoxical nature of our findings and suggesting that protective factors associated with selective migration potentially overcome substantial structural barriers,” the researchers explained.
LBW tied to long-term health issues
LBW is strongly associated with increased risks of infant morbidity and mortality, developmental delays, and long-term health issues. [Emerg Themes Epidemiol 2011;8:6] According to the researchers, the higher LBW prevalence in SG “is a significant concern for a small city-state where human capital is highly valued. SG’s puzzling case of high LBW prevalence, despite its world-class health system, offers an opportunity to advance regional comparative scholarship on migrant health.”
Data were extracted from the first wave of SG-LEADS** comprising 5,005 Singaporean children aged 0–6 years and their primary caregivers across 3,476 households. The final sample comprised 3,996 children born between 2011 and 2019. Sixty-three percent of children had both local-born parents, while 17 percent were from cross-national families with a foreign-born mum, primarily from China, Malaysia, India, Indonesia, the Philippines, Thailand, and Vietnam.
The lower LBW rate in cross-national families with foreign-born mums implies that early postnatal adversity may be a more important factor for future studies to understand developmental disadvantages among children in cross-national families, the researchers said.
“Public health strategies should move beyond one-size-fits-all approaches, addressing migration status, family formation dynamics, and structural inequalities,” they added.