Pregnancy outcome after in vitro fertilization (IVF) is influenced by many factors, some specific to IVF pregnancies and others shared with the general obstetric population. These factors include the characteristics of infertile couples and their underlying causes of infertility, the criteria used by IVF programmes for selecting couples for treatment, the techniques of fertilization and embryo transfer, the management of the early stages of pregnancy and the high incidence of multiple pregnancy. In comparing outcomes in different IVF programmes or with naturally conceived pregnancies, careful attention must be given to definitions and to the methods used to diagnose pregnancies. Very few studies of pregnancy outcome after IVF have been published so far. The incidence of ectopic pregnancy and spontaneous abortion seems higher than in natural pregnancies. Multiple pregnancy is common in those programmes electing to transfer more than one embryo into the uterus. In one study, preterm birth and low birthweight were about three times more common than in population-based figures. As a result, higher perinatal mortality would also be expected, but no studies are yet available. The sex ratio and the incidence of major congenital malformations appear similar to natural pregnancies, but there are insufficient data to determine whether the risks of chromosomal abnormalities are altered in IVF pregnancies. Further studies are needed to confirm these preliminary results, to obtain better information about the occurrence of chromosomal abnormalities in spontaneous abortions, and to assess fetal growth. Comparisons of results would be enhanced by international agreement on terminology and definitions for pregnancy losses, particularly those occurring in the early stages of pregnancy. Couples considering in vitro fertilization as an option for treatment of their infertility should be counselled about their overall chances of achieving a pregnancy and live births, as well as about the outcome of these pregnancies.
体外受精（IVF）后的妊娠结局受多种因素影响，有些因素是IVF妊娠所特有的，有些则与普通产科人群相同。这些因素包括不孕夫妇的特征及其不孕的潜在原因、IVF项目选择治疗夫妇的标准、受精和胚胎移植技术、妊娠早期的管理以及多胎妊娠的高发生率。在比较不同IVF项目的结局或与自然受孕的妊娠结局时，必须仔细注意定义和用于诊断妊娠的方法。到目前为止，关于IVF后妊娠结局的研究发表得很少。宫外孕和自然流产的发生率似乎高于自然妊娠。在那些选择向子宫内移植多个胚胎的项目中，多胎妊娠很常见。在一项研究中，早产和低出生体重的发生率比基于人群的数据高出约三倍。因此，围产期死亡率也可能更高，但目前尚无相关研究。性别比和主要先天性畸形的发生率似乎与自然妊娠相似，但尚无足够数据确定IVF妊娠中染色体异常的风险是否改变。需要进一步研究来证实这些初步结果，获取关于自然流产中染色体异常发生情况的更好信息，并评估胎儿生长情况。就妊娠丢失，特别是妊娠早期发生的妊娠丢失的术语和定义达成国际共识，将有助于增强结果比较。对于考虑将体外受精作为治疗不孕选择的夫妇，应就他们实现妊娠和活产的总体机会以及这些妊娠的结局提供咨询。
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