The literature on international migration and birth outcomes shows mixed results. The authors examined whether low birthweight (LBW) and preterm birth (PTB) differed between non-migrants and migrant subgroups, defined by race/ethnicity and world region of origin and destination.

The authors conducted a systematic review and meta-regression analyses using three-level logistic models to account for the heterogeneity between studies and between subgroups within studies.

Twenty four studies, involving more than 30 million singleton births, met inclusion criteria. Compared to US-born Black women, Black migrant women were at lower odds of delivering LBW and PTB babies. Hispanic migrants also exhibited lower odds for these outcomes, but Asian and White migrants did not. Sub-Saharan African and Latin American and Caribbean women were at higher odds of delivering LBW babies in Europe but not in the US and South-Central Asians were at higher odds in both continents, compared with the native-born populations.

The association between migration and adverse birth outcomes varies by migrant subgroup and it is sensitive to the definition of the migrant and reference groups.