Fewer infants born small for gestational age in China as conditions improve

Key takeaways:

• In China, small for gestational age prevalence decreased from 7.3% in 2012 to 5.3% in 2020.
• Improvements in health conditions and access to care may explain the changes.

The prevalence of infants born small for gestational age in China fell by more than 27% from 2012 to 2020, a change attributed to several improved maternal factors including access to care, researchers reported.

“Many variables have been associated with infants born small for gestational age, including economic conditions, health care quality, access to health care, maternal sociodemographic characteristics and preexisting diseases or prenatal complications. Many of these factors have changed substantially through China’s rapid socioeconomic development and adjustments in the traditional one-child policy,” Liangcheng Xiang, PhD, from the National Office for Maternal and Child Health Surveillance of China at West China Second University Hospital and the Key Laboratory of Birth Defects and Related Diseases of Women and Children at Sichuan University in China, and colleagues wrote in JAMA Network Open. “On one hand, the proportions of mothers aged older than 35 years and who have other pregnancy-related complications have increased, which may be associated with the risk of infants born small for gestational age. On the other hand, the proportions of mothers with higher educational levels and better access to high-quality health care have also increased, which may decrease the risk of infants born small for gestational age.”

For the cross-sectional study, researchers analyzed data from 12,643,962 singleton live births delivered from 2012 to 2020 in China, using data from the National Maternal Near Miss Surveillance System. Median gestational age at delivery was 39 weeks. Researchers evaluated delivery characteristics, including year, region of country and hospital level, as well as maternal and newborn characteristics. Primary outcome was small for gestational age prevalence stratified by severity and region in China, as well as changes in prevalence and any associations with changes in maternal characteristics.

Overall, the weighted small for gestational age prevalence was 6.4%, a decrease from 7.3% in 2012 to 5.3% in 2020.

In analyses stratified by infant size, researchers found the prevalence of small for gestational age births decreased for infants with severe low birth weight, falling from 2% to 1.2%, and for infants with mild to moderately low birth weight, falling from 5.3% to 4.1%.

Mean annual decrease rates were higher for infants with severe compared with mild to moderate small for gestational age birth weight (5.9% vs. 3.2%). In addition, mean annual decrease rates were higher for those living in less developed western (5.3%) and central regions (3.9%) compared with the eastern region (2.3%).

Maternal characteristics accounted for two-thirds of the observed decrease in small for gestational age prevalence, according to the researchers. These included education level (19.7%), age (18.8%), parity (19.4%) and prenatal visits (20.4%).

“The insights from this work may help target public health campaigns and interventions to specific subsets of women in particular parts of the country to further reduce the risk of infants born small for gestational age,” the researchers wrote.