Missing girls among deliveries from Indian and Chinese mothers in Spain 2007-2015

Deliveries from Indian and Chinese mothers present a higher than expected male:female ratio in their own countries, in northern Europe, EEUU and Canada. No studies have been carried out in southern European countries. We explored whether the high male-to-female ratio common in Indian and Chinese communities, also exists among families from those regions who live in Spain. For that purpose we designed a cross-sectional population-based study containing data on 3,133,908 singleton live births registered in the Spanish Vital Statistics Registry during the period 2007-2015. The ratio of male:female births by area of origin was calculated using binary intercept-only logistic regression models without reference category for the whole sample of births and taking into account a possible effect modification of birth order and sex of the previous males. Interaction effects of sociodemographic mothers' and fathers' characteristics was also assesed. In Spain, the ratio male:female is higher than expected for Indian-born mothers, especially for deliveries from mothers with no previous male births and, to a lesser extent, for Chinese-born women, specifically for third or higher order births and slightly influenced by the sex of the previous births. Therefore, the increased sex male:female ratio observed in other countries among Indian and Chinese mothers is also observed in Spain. This reinforces the notion that culture and values of the country of origin are more influential than the country of residence.