Women who live in the world's highest
communities tend to give birth to underweight babies, a new study suggests.
These babies may grow into adults with a high risk of heart disease and
strokes. Research has hinted that newborns in mountain
communities are lighter than average. But it wasn't clear whether this is due to
reduced oxygen levels at high altitude or because their mothers are
under-nourished—many people who live at high altitudes are relatively poor
compared with those living lower down. To find out more, Dino
Giussani and his team at Cambridge University studied the records of 400 births
in Bolivia during 1997 and 1998. The babies were born in both rich and poor
areas of two cities: La Paz and Santa Cruz. La Paz is the highest city in the
world, at 3.65 kilometers above sea level, while Santa Cruz is much lower, at
0.44 kilometers. Sure enough, Giussani found that the average
birthweight of babies in La Paz was significantly lower than in Santa Cruz. This
was true in both high and low-income families. Even babies born to poor families
in Santa Cruz were heavier on average than babies born to wealthy families in
lofty La Paz. "We were very surprised by this result," says Giussani.
The results suggest that babies born at high altitude are deprived of
oxygen before birth. "This may trigger the release or suppression of hormones
that regulate growth of the unborn child," says Giussani. His
team also found that high-altitude babies tended to have relatively larger heads
compared with their bodies. This is probably because a fetus starved of oxygen
will send oxygenated blood to the brain in preference to the rest of the
body. Giussani wants to find out if such babies have a higher
risk of disease in later life. People born in La Paz might be prone to heart
trouble in adulthood, for example. Low birthweight is a risk factor for coronary
heart disease. And newborns with a high ratio of head size to body weight are
often predisposed to high blood pres- sure and strokes in later life.
单选题
What does the new study discover?
A. Babies born to wealthy families are heavier.
B. Women living at high altitude tend to give birth to underweight
babies.
C. Newborns in cities are lighter than average.
D. Low-altitude babies have a high risk of heart disease in later
life.
【正确答案】
B
【答案解析】[解析] 由第一段第一句“Women who live...tend to give birth to underweight babies...”可知，一项新的研究发现，居住在高海拔地区的女性易生下体重不足的婴儿，故选B。
单选题
Giussani and his team are sure that ______.
A. babies born in La Paz are on average lighter than in Santa Cruz
B. people living in La Paz are poorer than those in Santa Cruz
C. the birthweight of babies born to wealthy families is above average
D. mothers in La Paz are commonly under-nourished
【正确答案】
A
【答案解析】[解析] 由第四段第一句“...the average birthweight of babies in La Paz was significantly lower than in Santa Cruz.”可知，Giussani发现La Paz的婴儿平均出生体重比Santa Cruz的婴儿平均出生体重低，故选A。
单选题
It can be inferred from what Giussani says in Paragraph 4 that ______.
A. the finding was unexpected
B. he was very tired
C. the study took longer than expected
D. he was surprised to find low-income families in La Paz
【正确答案】
A
【答案解析】[解析] 由第四段最后一句中Giussani的话“We were very surprised by this result”可知，研究结果是出人意料的，故选A。
单选题
The results of the study indicate the reason for the birth of
underweight babies is ______.
A. lack of certain nutrition
B. poverty of their mothers
C. different family backgrounds
D. reduction of oxygen levels
【正确答案】
D
【答案解析】[解析] 由第五段第一句“The results suggest that babies born at high altitude are deprived of oxygen before birth.”可知，研究结果表明，在高海拔地带出生的婴儿出生前就缺氧，这也就是造成其出生体重低的原因，故选D。
单选题
It can be learned from the last paragraph that ______.
A. high-altitude babies tend to have high blood pressure in their later
life
B. underweight babies have a shorter life span
C. babies born to poor families lack certain hormones before birth
D. newborns in wealthy families have larger heads compared with their
bodies