The rate of birth anomalies in China has increased slightly in the years since it replaced its one-child policy with a two-child policy, perhaps because people are having second children when they are older.
China鈥檚 one-child policy, which began in 1979, was replaced in 2013 with a partial two-child policy that permitted couples to have two children if one or both of them were only children themselves. In 2015, this right was extended to all couples.
In the years following the policy shift, there has been a rise in fetal and congenital anomalies like Down鈥檚 syndrome, heart defects, cleft lip and ear malformations, according to a study by Xiaohui Zhang and Lijin Chen at Zhejiang University in China and their colleagues. They examined the records of more than 1.2 million live births, stillbirths, miscarriages and abortions that occurred between 2009 and 2017.
Advertisement
Screening during pregnancy and following birth showed that fetal and congenital anomalies occurred in 246 out of every 10,000 pregnancies during the one-child policy, 265 per 10,000 pregnancies during the partial two-child policy and 304 per 10,000 pregnancies during the universal two-child policy.
Age effect
The rise in such anomalies is probably related to women in China having babies later in life now that they can have more than one child, says Jane Halliday at Murdoch Children鈥檚 Research Institute in Australia. Women鈥檚 eggs are more likely to develop chromosomal changes as they age, which can lead to certain conditions in the fetus, she says.
In line with this, the study found that the proportion of women in China who gave birth when they were 35 or older was 9 per cent during the one-child policy and 16 per cent after the universal two-child policy was introduced.
The study didn鈥檛 look at the age of fathers. Paternal age makes a relatively minor contribution to congenital anomalies, says Lisa Hui, also at Murdoch Children鈥檚 Research Institute 鈥� although some studies suggest otherwise.
The jump in fetal and congenital anomalies shouldn鈥檛 be considered alarming because it simply brings China closer to countries with no restrictions on family size, says Hui. Down鈥檚 syndrome, for example, now occurs in 12 out of 10,000 pregnancies in China, which is still lower than in the US where it occurs in about 15 per 10,000 pregnancies.
Moreover, the new study shows that some anomalies have become less common in China in recent years. For example, neural tube defects have declined since the country launched campaigns to increase the number of women taking folic acid supplements in early pregnancy.
鈥淭he findings suggest that when you make a big change to reproduction on a population level, you should be prepared for a change in the health burdens that you鈥檒l see,鈥� says Hui. Studying these changes allows health services to respond, for example, by being more alert for congenital heart defects so that management plans can be drawn up for affected babies before they are born, she says.
PLoS Medicine
