Health equity
Did China’s two-child policy change birth defects?
Open access · cc by · source: Europe PMC
In 1.26 million Zhejiang births, advanced maternal age nearly doubled after the two-child policy and total birth-defect prevalence rose, especially chromosomal anomalies.
Study at a glance
- Design
- Cross-sectional — Serial hospital-based birth-defect surveillance comparing one-child, partial two-child, and universal two-child policy periods in Zhejiang
- N
- N=1260684 · 1,260,684 births (live births, early fetal losses, stillbirths, early neonatal deaths) across 2009–2017 surveillance years
- Population
- Births captured by Zhejiang Province BD surveillance covering 90 hospitals (about one-third of provincial births)
- Outcome
- Maternal age distribution, prevalence and ranking of birth defects, prenatal diagnosis timing, and live-birth rate of BDs before 28 weeks
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Key findings
Births to mothers ≥35 rose 85.68% (8.52% in 2013 to 15.82% in 2017). BD prevalence rose from 245.95 to 304.36 per 10,000 births. Trisomy 21 crude OR was 2.13; other chromosomal defects OR 3.63. Live birth of BDs before 28 weeks rose from 1.29% to 11.45%.
Methodology
Compared BD surveillance years representing the one-child (2013), partial two-child (2015), and universal two-child (2017) periods, using 90 hospitals covering about one-third of Zhejiang births, and also showed pre-policy age trends (2009, 2011).
Limitations
Observational surveillance cannot prove the policy caused defects; unknown confounders and changing prenatal detection may contribute.
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