Screening for microcephaly is important at birth and during early childhood. The Guangzhou Surveillance and Clinical Study in Microcephaly (GSCSM) aims to establish a multicentric surveillance system for microcephaly in newborns and infants, to develop a new head circumference reference and microcephaly criteria basing on the local population in Guangzhou, to improve the prediction model of microcephaly, and to follow up the outcomes of the children diagnosed with microcephaly.

Microcephaly is associated with neurological dysfunctions in infants and children. There is not a uniform diagnostic criteria for microcephaly. The World Health Organization (WHO) recommended a criteria of head circumference (HC) less than 2 standard deviations (SD) below the mean of the Intergrowth-21 standard, which was found not applicable to the newborns and infants in Guangzhou.In the GSCSM, the HC measures of newborns are conducted by trained midwives using a standard tool, and extensive information including adverse perinatal outcomes are collected. Longitudinal follow up of infants' neurodevelopment in cognitive, motor, emotional and other domains are also to be conducted. The GSCSM intends to find out the infants who are 'real microcephaly' and most at risk of short-term or long-term adverse outcomes in Guangzhou.

Inclusion Criteria:

1. Newborns born after 24+0 weeks of gestation
2. Newborns delivered at the study hospitals

Exclusion Criteria:

1. With major congenital abnormalities
2. Multiple births

The study population are infants born in the maternity hospitals from Guangzhou surveillance system.