医学新闻：胎儿在母亲子宫里的时间越长，出生后孩子越聪明

The longer a baby stays in the womb, the smarter the child, new research shows.

A study using New York City public school children has found improved brain development and better academic test scores for full-term infants born even a few weeks later than others.

A baby is considered fully developed between 37 and 41 weeks and premature if delivered before.

Researchers compared 128,000 New York kids, including many from disadvantaged families, born at 37 weeks and 41 weeks and found slightly better reading and math skills for those born later.

In total, 15% of the babies in the study were delivered by Caesarean section and factors such as low birth weight and smoking during pregnancy were also factored in.

Researchers say the findings raise questions about the medical definition of prematurity and whether women should be allowed to schedule Caesareans early for convenience.

Mothers-to-be should “at least proceed with caution before electing to have an earlier term birth,” lead author Dr. Kimberly Noble, an assistant pediatrics professor at Columbia University Medical Center, said.

The differences in the test scores between the younger and older group of children were small but noticeable.

Among the infants born at 37 weeks, 2.3% had severely poor reading skills and 1.1% had at least moderate problems in math.

For kids born four weeks later, the results were 1.8% and 0.9% respectively.

Children born at 37 weeks were also a third more likely to have severe reading difficulty in third grade, and a 19% greater chance of having moderate problems in math, compared with 41-weekers.

Dr. Judy Aschner, a pediatrics professor and neonatology director at Vanderbilt University Medical Center, believes the results “will cause quite a stir.”

“There are still a lot of babies who are being delivered more or less electively at 37 and 38 weeks, with people thinking, ‘This is no big deal. These babies are full-term.’ I think this is a big deal,” Aschner told The Associated Press.

“I don’t want to panic moms whose babies come at 37 weeks,” added Aschner, who was not involved in the study. “But those elective early deliveries really need to stop.”

The results were published Monday in the journal Pediatrics.

人们早已知道，早产（不足37周出世）婴儿会面对健康和智力问题。最新的研究发现，足月（37到41周）出世的婴儿，如果在母体内多待一两个星期，对脑力健全发展会大有好处。

联合早报报道 人们早已知道，早产（不足37周出世）婴儿会面对健康和智力问题。最新的研究发现，足月（37到41周）出世的婴儿，如果在母体内多待一两个星期，对脑力健全发展会大有好处。

参加美国这项调研的孩子全都是足月生产，他们大多在三年级的数学和朗读测试中表现很好。不过，调查也发现，怀孕37周和38周出生的孩子，表现比晚一两个星期出生的孩子差一些。

研究人员认为，这一结果说明，应该重新考虑早产的定义了。

研究结果也对由于非医疗原因、通过安排剖腹产提早分娩的问题提出质疑。

报告主作者、哥伦比亚大学医学中心儿科助理教授诺布尔说，妇女“在选择提早生产之前，至少应该慎重的考虑一番”。

参加此项调查的是12万8000名纽约市公立学校的学生，他们包括相当数量来自贫困家庭的孩子。那些怀孕37周出生的孩童中，2.3%有较大的阅读困难，1.1%有中度的数学问题；与之相比，怀孕41周出生的孩子，有上述问题的比例分别为1.8%和0.9%。

在怀孕38周出生的孩子，出现上述情况的风险，略微低于37周的孩童。

有15%接受调查的儿童是经剖腹产出生的。剖腹产可能导致生育并发症，这也可能造成发育迟缓。即使研究人员把这考虑在内，再加上出生时体重过低、缺乏产前护理，怀孕期间吸烟和生活在贫困社区等因素，他们还是发现，37周和38周出现的孩子面对额外的风险。