推延生育有危险，妈妈须慎重！
依据前四年的统计数据，从属美国疾病防备控制中心的国家卫生统计局在星期五宣布了一份政府 陈述，该陈述指出：越来越多女人超越35岁才预备怀孕。
详细如下：
1、2012年，35岁之后初次生养的女人的数量是20世纪70年代人数的9倍之多。
2、2000年至2012年期间，40至44岁初次生养的女人的人数上升了35%，35至39岁的人数上升了24%。
3、40至44岁的人数是1990年的两倍多。
4、曩昔的20年里，各种族大龄女人的初次生养率均有所上升，其间，非西班牙裔白人、黑人、亚洲人和太平洋岛民尤为显着。
研讨人员还调查了各州大龄女人的初次生养率，发现只要密西西比州、俄克拉何马州、亚利桑那州和爱达荷州的数据没有明显改变。
这项研讨陈述的作者们指出，女人推延生养各有利弊：大龄妈妈比较于较早生养的年青妈妈们有更多的资源，比方更高的收入水平和更高的文化教育程度，但一起，她们跟孩子更可能有一些健康危险。
南加州生殖医学中心研讨发现，一个20多岁的女人在每次来月经时的天然怀孕机率是20%—25%，该年龄段女人的流产机率大约是5%—10%。
到34岁时，女人的天然怀孕机率下降到15%，流产率为20%。而超越45岁的女人仅有1%的怀孕率，且流产率是她们20岁时的5倍。
编译自：
Women waiting longer to have their first child
More women over 35 are giving birth for the first time, according to a government study released Friday. The report, issued by the National Center for Health Statistics at the Centers for Disease Control and Prevention, looked at data compiled over the past four decades.
Among the findings:
In 2012, there were more than nine times as many first births to women over age 35 than in the 1970s
From 2000 to 2012, first birth rates rose 35% for women aged 40 to 44, and 24% for women aged 35 to 39
The first birth rate for women aged 40–44 has more than doubled since 1990
In the past 20 years, first birth rates rose for older women across all races. The largest increases were seen for non-Hispanic white and black women, and Asian or Pacific Islander women
The study also looked at first birth rates state-by-state. Researchers found only Mississippi, Oklahoma, Arizona and Idaho had no significant birth rate change for older women.
The study authors point out that there are pros and cons for women waiting to have children. Older moms typically have more resources, including higher incomes and better education than younger first-time moms. But women who have their first children after 35 are more likely to have health problems, as are their children.
According to the Southern California Center for Reproductive Medicine, a woman in her 20s has a 20 to 25% chance of conceiving naturally every time she menstruates. At that age, the rate of miscarriage is anywhere from 5 to 10%. By 34, the likelihood of a woman conceiving naturally drops to 15%, and the miscarriage rate is 20%. Women over 45 have a 1% chance of conception, and are five times as likely to miscarry as women in their 20s.
