具有双胞胎的人类是这种事件中最常见形式的人类罕见的。许多出生可能会出现多个诞生
与整个人类相比，不同的方式的不同组合，但生育超过一个孩子的概率仍然相当恒定。多个出生物的机会也可以从种族和遗传背景不同。科学家和研究人员不知道这些变化的确切原因是什么，但其中许多人认为它是由不同种族群体之间的激素差异和/或社会阶层的差异引起的。多重妊娠的产前和婴儿死亡率远远高于仅涉及一个孩子的怀孕。早产的危险也随着涉及的后代数量增加而增加。在许多多个出生中，并非所有的孩子都幸存到童年或生于死亡。通过技术进步，在多次怀孕中出生的婴儿的存活率增加。第一个Quintuplets，五个婴儿出生于单身怀孕，在病史中生存是狄尼Quintuplets。使用治疗女性不含失育率或生育药物的药物可能会增加生育多种儿童的机会。这些药物导致卵巢每月释放一次鸡蛋，但在某些情况下，他们释放了多个鸡蛋，有时一次释放几个鸡蛋，增加了多次出生的机会。 The drug clomiphene citrate is one of the most widely taken fertility drug and has resulted in the birth of twins about once in every twelve births, much greater than the chances of the birth of natural twins. Twins are the most common form of a multiple pregnancy. About one in eighty-seven births result in the birth of twins. Twins can be fraternal, also known as dizygotic twins, or identical, also called monozygotic twins, with the birth of identical twins being the rarest, occurring about four times in every thousand births, about one-forth as often as the birth of fraternal twins.
双胞胎诞生与出生总数的比率仍然相当不变，但兄弟双胞胎的诞生可以大大改变。兄弟双胞胎在黑色非洲之后是欧洲原产人的最常见。来自东方的亚洲比赛最不可能生育兄弟双胞胎。双胞胎的诞生可以以两种不同的方式发生，施肥单个鸡蛋或两种卵子的施肥。在Dizygotic双胞胎的情况下，女人的卵巢释放了两个鸡蛋约同一时间而不是一个鸡蛋，每次被男性精子受精，兄弟双胞胎开始发展。两个Zygotes不同地发展，每个都具有不同的遗传编码。他们可以是男孩，两个女孩，或一个男孩和一个单身女孩。因为每个胚胎都来自不同的遗传特征，因为Dizygotic Twins类似于兄弟和姐妹的家庭特征。单卵锥双胞胎的诞生比兄弟双胞胎的出生方式发生得多。同样的双胞胎源自单一蛋，与单一妊娠类似的蛋。 A change transpires early in the pregnancy that causes the development of identical twins. The change from a single birth to the birth of monozygotic twins occurs when the zygote ruptures into two separate structures. These two parts begin to develop into individual fetuses, sharing a similar genetic code and developing in a similar manner. Identical twins are of the same sex, resemble each other very closely, and have similar fingerprints and blood types. Scientists also believe that Siamese twins, also known as conjoined twins, develop in a similar fashion as do monozygotic twins. Siamese twins are identical twins with the difference that the zygote did not divide completely during their development. Such twins are usually joined at the hip, chest, abdomen, buttocks, or head. With current monitoring equipment, conjoined twins can be detected maturing in the mother and during birth a Cesarean section is sometimes needed to deliver the children safely. Separation of the twins sometimes leads to the death of one or both of the twins.
这些出生是一个罕见的事件，只有每五万诞生中的一个大约一个。其他形式的多重诞生如三胞胎，四重奏和Quintulets，与双胞胎的出生非常相似。三胞胎的诞生比双胞胎的诞生稀有，每七千九百个诞生大约发生一次。三元组的诞生可以以多种方式发生。如果Zygote在发展早期的发展中分为三个单独的结构，那么同样的双胞胎将出生。如果两种细胞受精，并且一个分为两种结构，如单卵双胞胎，一对相同的双胞胎的诞生将与单一婴儿一起出生。如果卵巢释放了三个鸡蛋，那么受精，那么将发生兄弟三胞胎的诞生。在四核，Quintultets和六个孩子怀孕的非常罕见的情况下，可以观察到相同水平的组合。每七百五千的诞生和Quidruplet的诞生只在每八百万分娩中诞生一次。六个婴儿的诞生是如此罕见，不能在与世界各地的出生总量相比时进行准确的统计数据。 In all of these forms of multiple pregnancies, the process is very similar. If the woman’s ovaries release four or five eggs then the birth of quadruplets or quintuplets will arise. If the cell divides into four of five structures will then cause the pregnancy of identical quadruplets or quintuplets. These and numerous other combinations can occur as the number of infants involved increases. Multiple pregnancies are a rare occasion, one of the factors for the incomplete statistics of the birth of a six child pregnancy. The number of infants born in multiple births, as well as larger births consisting of six or more children, are also increasing due to the use of fertility drugs. This widespread use is forcing researchers not to accept any multiple births that were endorsed by drugs as part of the general statistics. Some aspects of multiple births are still not clear to scientist. The difference between the probabilities of multiple pregnancies of women of different races is just one of these problems. More about multiple births has been learned over the ages but more is still to be learned and tested by scientists.
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