Robinson H P, Caines J S
Br J Obstet Gynaecol. 1977 Jan;84(1):22-5. doi: 10.1111/j.1471-0528.1977.tb12460.x.
During a four-year period 30 patients were diagnosed by sonar in the first trimester of pregnancy as having twin conceptions. Of these 30 patients, 14 eventually gave birth to twins. Eleven of the remaining 16 patients were found to have a normal pregnancy and a coexistent blighted ovum (empty sac), and ultimately all but one gave birth to a single baby; the eleventh patient aborted a fresh fetus at 25 weeks of gestation. Of the last five patients, four were diagnosed as having twin blighted ova, and one a blighted ovum and missed abortion; these five patients either aborted spontaneously or had an elective termination of pregnancy. The results suggest that the incidence of twin conceptions is higher than commonly accepted figure of 1 in 80.
在四年期间，30名孕妇在妊娠早期通过超声检查被诊断为怀有双胎妊娠。在这30名患者中，14名最终产下双胞胎。其余16名患者中，11名被发现怀有正常妊娠且并存枯萎卵（空囊），最终除1名患者外均产下单胎婴儿；第11名患者在妊娠25周时流产了一个新鲜胎儿。在最后5名患者中，4名被诊断为双胎枯萎卵，1名被诊断为枯萎卵合并稽留流产；这5名患者均自然流产或接受了选择性终止妊娠。结果表明，双胎妊娠的发生率高于普遍认为的80分之一。
