Vitamin D status and the prevalence of deficiency in lactating women from eight provinces and municipalities in China

Vitamin D deficiency has become prevalent worldwide in recent years. However, less evidence was available for lactating women.The purpose of the study was to understand vitamin D status and prevalence of deficiency in lactating women and associated risk factors for vitamin D deficiency from eight provinces and municipalities in China.Lactating women within 1–10 months postpartum were recruited in 2011–2013 from eight provinces and municipalities in China. Radioimmunoassay was used to measure serum 25-hydroxyvitamin D [25(OH)D] concentration. Standardized questionnaire was used to collect information on season, living site, ethnicity and socio-demographic characteristics.