美国卫生官员表示，美国双胞胎出生人数已经降至十年来的最低水平。
The U.S. Centers for Disease Control and Prevention, CDC, reported the decrease. Twin births nationwide began to increase about 40 years ago, CDC records show. From 1980 until 2014, the total number rose 79 percent.
美国疾病预防控制中心报告了这一减少的情况。该中心的记录显示，全美国双胞胎的出生数量大约在40年前开始增长。从1980年到2014年，双胞胎总人数增加了79%。
But from 2014 to 2018, the twin birth rates fell 4 percent. Last year, there were 32.6 twins for every 1,000 total births, the CDC reported.
但是从2014年到2018年，双胞胎出生率下降了4%。美国疾病预防控制中心报告称，去年每1千名新生儿中就有32.6人是双胞胎。
While the latest drop was not huge, officials said they consider it a good sign. Pregnancy with more than one child raises the risks of complications and death for both the mother and the baby.
虽然双胞胎出生率最近的跌幅不算很大，但官员们表示他们认为这是一个好兆头。怀上多胞胎增加了母亲和婴儿发生并发症和死亡的风险。
Dmitry Kissin is a doctor who works with the CDC's Division of Reproductive Health. He told The Associated Press that many people do not realize there can be serious risks with twin births.
德米特里·基辛是美国疾病预防控制中心生殖健康部门的一位医生。他对美联社表示，许多人没有意识到双胞胎会带来巨大的风险。
"In the media," he said, "there are often stories about very cute twins and talking about how great to have two babies at the same time." Such stories ignore the health risks, Kissin added.
他说：“媒体上经常有关于非常可爱的双胞胎的新闻，称同时生下两个宝宝有多美好。”基辛表示，这类新闻忽视了健康风险。
In 2018, about 124,000 babies born in the United States were twins. That represents about one in every 31 births.
2018年，美国大约有12.4万名新生儿是双胞胎。这代表每31名新生儿中就有一人是双胞胎。
Health experts say there is no single explanation for the falling twin birth rates.
健康专家表示，双胞胎出生率下降没有单一的解释。
However, Joyce Martin, the lead writer of the report, suggested one likely reason. She noted that the falling rates were only among white women and in women 30 years of age or older. Women from these groups are the biggest users of in vitro fertility treatments.
然而，该报告的主要作者乔伊斯·马丁提出了一种可能。她指出，双胞胎出生率仅在白人妇女和30岁以上妇女中的有所下降。这群女性是人工受孕的最大客户。
In vitro fertilization is when doctors combine male and female cells to create an embryo, which is later implanted in a woman's uterus. This technique results in about 15 percent of all births involving more than one baby.
人工受孕是指医生将精子和卵子结合形成一个胚胎，然后将其植入女性的子宫中。这项技术导致大约15%的孕妇会生出多胞胎。
In the past, it was common for fertility experts to implant two or more embryos to improve the chances of a successful birth. This greatly increased the woman's chances of having more than one baby.
过去，生育专家通常会植入两个或多个胚胎来提高成功分娩的几率。这大大增加了女性产下多胞胎的几率。
In recent years, however, the method has changed. Fertility specialists now grow embryos longer in the lab and carry out more tests for genetic problems. They then choose the best single embryo to implant.
然而近年来，这种方式有所改变。生育专家现在让胚胎在实验室中发育更长时间，并对遗传问题进行检测。然后他们选择最佳的单个胚胎进行植入。
The CDC's Dmitry Kissin says that today, about two-thirds of in vitro fertility treatments involve just one embryo.
美国疾病预防和控制中心的基辛表示，如今大约2/3的人工受孕只涉及一个胚胎。
Aaron Styer is an infertility treatment specialist in Chestnut Hill, Massachusetts. He told The AP the success rate for one embryo rose from about 20 percent in the 1980s to around 50 percent today.
亚伦·斯特尔是马萨诸塞州栗子山市的不育治疗专家。他对美联社表示，单个胚胎的成功率从上世纪80年代的20%上升到了如今的50%左右。
Styer said that health insurance companies and medical organizations have increasingly been pushing doctors to implant just a single embryo. More and more patients are also accepting the method to improve their chances of a successful pregnancy, he added.
斯特尔说，健康保险公司和医疗机构日益推动医生只植入单个胚胎。他还说，越来越多的患者也接受这种方式来提高成功妊娠的机会。
I'm Bryan Lynn.
我是布莱恩·琳恩。(51VOA.COM原创翻译，禁止转载，违者必究！)