Cohort profile: the Shenzhen Birth Cohort (SZBC) study

The Shenzhen Birth Cohort (SZBC) is an ongoing prospective study established to investigate the impact of genetic, environmental and lifestyle factors on maternal health and child development in Shenzhen, a metropolis characterised by rapid economic development and a high density of young migrants.

Since March 2018, pregnant women (≤19 weeks of gestation) have been recruited from Nanshan Maternity & Child Healthcare Hospital of Shenzhen. Follow-up assessments are conducted at up to 20 time points from early pregnancy through delivery and childhood (up to 7 years of age). Extensive health data were collected through standardised questionnaires, physical examinations and biological samples (eg, blood, urine, faeces).

As of December 2025, 4208 pregnant women were enrolled, of whom 3962 completed baseline data collection and constituted the baseline cohort; 3150 deliveries had been recorded. Preliminary findings included the following: (1) Maternal lifestyles and adverse birth outcomes: poor sleep quality in early pregnancy was associated with higher risks of small-for-gestational-age (SGA). (2) Maternal health conditions and neurodevelopment: higher pre-pregnancy BMI was associated with developmental delays in offspring, particularly in boys. (3) Environmental exposures and neurodevelopment: prenatal exposure to greenness was associated with higher levels of motor development, whereas postnatal PM₂.₅ exposure (notably nitrate) was associated with increased risks of delayed motor and problem-solving development.

Recruitment is planned to continue through 2028, with enrolled children undergoing regular follow-up through 7 years of age. The current phase of cohort follow-up is expected to be completed in 2035. Future studies will integrate electronic medical records and multi-omics data to examine the combined effects of early-life exposures and explore potential biological pathways related to maternal and child health.