醫學新聞：胎兒在母親子宮裏的時間越長，出生後孩子越聰明

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.

人們早已知道，早產（不足37周出世）嬰兒會麵對健康和智力問題。最新的研究發現，足月（37到41周）出世的嬰兒，如果在母體內多待一兩個星期，對腦力健全發展會大有好處。

聯合早報報道 人們早已知道，早產（不足37周出世）嬰兒會麵對健康和智力問題。最新的研究發現，足月（37到41周）出世的嬰兒，如果在母體內多待一兩個星期，對腦力健全發展會大有好處。

參加美國這項調研的孩子全都是足月生產，他們大多在三年級的數學和朗讀測試中表現很好。不過，調查也發現，懷孕37周和38周出生的孩子，表現比晚一兩個星期出生的孩子差一些。

研究人員認為，這一結果說明，應該重新考慮早產的定義了。

研究結果也對由於非醫療原因、通過安排剖腹產提早分娩的問題提出質疑。

報告主作者、哥倫比亞大學醫學中心兒科助理教授諾布爾說，婦女“在選擇提早生產之前，至少應該慎重的考慮一番”。

參加此項調查的是12萬8000名紐約市公立學校的學生，他們包括相當數量來自貧困家庭的孩子。那些懷孕37周出生的孩童中，2.3%有較大的閱讀困難，1.1%有中度的數學問題；與之相比，懷孕41周出生的孩子，有上述問題的比例分別為1.8%和0.9%。

在懷孕38周出生的孩子，出現上述情況的風險，略微低於37周的孩童。

有15%接受調查的兒童是經剖腹產出生的。剖腹產可能導致生育並發症，這也可能造成發育遲緩。即使研究人員把這考慮在內，再加上出生時體重過低、缺乏產前護理，懷孕期間吸煙和生活在貧困社區等因素，他們還是發現，37周和38周出現的孩子麵對額外的風險。