Of the 755 born at 23 weeks, treatment was given to 542. About a third of those survived, and about half of the survivors had no significant problems.

在23周出生的755个早产儿中，有542个得到了医疗护理。其中大约有三分之一存活，约一半存活者没有明显的健康问题。

As techniques for keeping babies alive improve, parents face wrenching choices that are sometimes based on whether the estimated age is 22 weeks and one day or six days. The study found that hospitals tend to “round up,” with babies closer to 23 weeks more likely to receive treatment.

随着让婴儿能存活技术的改善，父母面临着痛苦的选择。有时这种选择是基于对可独立存活胎龄的估计是22周零一天还是零六天。这项研究发现，医院往往会“四舍五入”，接近23周出生的早产儿更有可能得到医疗护理。

But the authors and other experts also noted that gestational age is an educated guess, based on women’s recollection of their last menstrual period and estimated fetal size. Other factors, including prenatal care and the fact that girls are often a week more mature than boys, should also influence decisions, experts say.

但是，论文作者和其他专家也指出，胎龄只是一个有根据的推测，根据的是孕妇对自己最近一次月经来潮日期的回忆，以及所估计的胎儿大小。专家说，其他因素，包括产前检查，以及女胎儿往往比男胎儿早成熟一周的事实，也应该影响决定。

“It’s very difficult to say to a mother, ‘If you deliver today, I’m going to do nothing, but if you deliver tomorrow, I’m going to do everything,’ ” said Dr. Neil Marlow, a neonatologist at University College London.

伦敦大学学院(University College London)的新生儿专家尼尔·马洛博士(Dr. Neil Marlow)说，“很难对一位母亲说，‘如果你今天生，我会什么都不做，但如果你明天生，我会尽一切努力。’”

The study, which evaluated cases from 2006 to 2011 at 24 hospitals in a neonatal network supported by the National Institute of Child Health and Human Development, found that four of the hospitals intervened for no 22-week-olds, five intervened for all 22-week-olds and the rest varied. In all, about a fifth of the 357 babies that age were treated. The reasons could include family preferences and hospital policy, the authors wrote.

这项研究评估了由美国儿童健康和人类发展研究所支持的24家医院参与的新生儿网络中，从2006年至2011年期间的病例，发现四家医院对22周出生的早产儿没有进行医学干预，五家医院对22周出生的婴儿进行了干预，其他的医院视情况而定。总的来说，所有接受医疗护理的357名22周出生的婴儿中大约有五分之一接受了护理。是否治疗的原因可能包括家庭的选择和医院的政策，作者写道。

“We can’t really say whether the differences revolve around differences in values, that for some physicians or parents the risk of impairment might outweigh the decision for treatment,” said Matthew Rysavy, a medical student at the University of Iowa, who led the study with Dr. Edward Bell, a pediatrics professor there. At Iowa, Dr. Bell said, treatment is offered to most 22-week-olds, and he considers 22 weeks a new marker of viability.

“我们确实不能说，治疗选择上的差异是否是价值观上的差异。对一些医生或家长来说，（孩子存在）身体障碍的风险可能在做治疗决定时起较大作用，”艾奥瓦大学医学院学生马修·莱萨维(Matthew Rysavy)说，他和医学院的小儿科教授爱德华·贝尔博士(Dr. Edward Bell)一起领导了这项研究。贝尔说，在艾奥瓦州，大多数22周的早产儿都得到医疗护理，他认为22周是独立存活的新标准。

“That’s what we think, but this is a pretty controversial area,” Dr. Bell said. “I guess we would say that these babies deserve a chance.”

“我们这样认为，但这是一个非常有争议的领域，”贝尔说。 “我想我们会说，这些婴儿应该得到一个机会。”

Dr. Jeffrey M. Perlman, medical director of neonatal intensive care at NewYork-Presbyterian Hospital Weill Cornell Medical Center, takes a different view. He said it was important to consider that long months in neonatal units can be “like riding an obstacle course or flying in a plane with bad turbulence, and each of these down spirals can have an impact on the brain.”