Very Low, Low and Heavy Weight Births in Hong Kong SAR: How Important is Socioeconomic and Migrant Status?

Identification of modifiable factors and mediators linked to low and heavy birth weight is crucial in reducing infant mortality and health care expenditure. The present paper explores the associations of socio-demographic factors and immigrant status of parents with adverse pregnancy outcomes in Hong Kong. The analysis compares very low birth weight (VLBW: <1500 g), low birth weight (LBW: ≥ 1500 g and <2500 g) and heavy birth weight births (HBW: ≥ 4500 g) with births of normal weight (≥ 2500 g and <4500 g) using multinomial regression modelling of a large dataset of 828,975 births of singletons occurring between 1995 and 2009. The findings indicate the expected significant adverse associations between teenage and advanced age of the mother with compromised birth outcomes; teenage motherhood, however, has a protective effect against HBW births. A strong socioeconomic gradient is apparent, more marked among LBW births; low educational attainment of the father, low occupational class, public housing and single motherhood are strongly related to adverse pregnancy outcomes. Regarding immigrant status, women born in South and South-East Asia exhibit consistently higher odds of a compromised outcome. Women born in Hong Kong have significantly higher chances of LBW births while Mainland Chinese and parents from developed countries face higher odds of HBW births. The study identifies high-risk groups such as teenage, older and single mothers, South-East Asians and couples of low socioeconomic profile. Implementation of policies supporting these groups would be beneficial.