The relationship between preterm birth and underweight in Asian women

•Association between underweight and preterm birth is reported in developed countries.•This association is not indicated for Asian women.•Use of BMI cut-offs for developed countries may attenuate this association in Asians.•Country specific BMI cut points should be used to determine underweight in Asian women.

Although vast improvements have been made in the survival of preterm infants, the toll of preterm birth (PTB) is particularly severe in Asia, with the Indian subcontinent leading the preterm birth rate. Despite the obesity epidemic, maternal underweight remains a common occurrence in developing countries. An association between maternal underweight and preterm birth has been reported in developed countries. A review of epidemiological studies in Asian women in whom association between maternal body mass index (BMI) and risk of PTB was measured, indicated no significant association between low maternal BMI and preterm birth. A hindrance in comparison of these studies is the use of different cut-off point for BMI in defining maternal underweight. As a commentary on published studies it is proposed that that country-specific BMI cut points should be applied for defining underweight for Asian women for the purpose of evaluating the association between maternal underweight and preterm birth.