四级练习2015.01.06
[audio]http://sound.yywz123.com/tingbbs/cet4/cet420150106.mp3[/audio]Around the world, cesarean births are on the rise, and many experts think that's a bad thing. Now, a new study looks at one way that babies delivered by c-section are different.
(1)_________________________________. Some cesareans are medically necessary. But in other cases, women just want the convenience of knowing when they will give birth. For some, it's the modern thing to do. Doctors like that predictability, too. And health care providers usually charge more.
A World Health Organization survey of hospital and clinic births in 9 Asian countries earlier this year found 27% were c-sections, and (2)_________________________. And there were more deaths and complications when women had a cesarean delivery that wasn't medically required. Other research has found c-section babies are more likely to have asthma or allergies.
Now, a small but intriguing new study looks at one way (3)_________________________. Co-lead author Elizabeth Costello, now at Stanford, was at the University of Colorado when the study was done.
"We were looking at the effect of delivery mode on the very first bacteria that the baby is exposed to. So we sampled babies literally seconds and minutes after they were delivered. And so we're only looking at a snapshot of that very first moment in time."
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