What best describes "ectopic pregnancy"?

The term "ectopic pregnancy" specifically refers to a situation in which a fertilized egg implants and begins to develop outside of the uterine cavity, most commonly in the fallopian tubes. This abnormal placement prevents the embryo from developing properly and poses significant health risks to the individual, such as internal bleeding if the ectopic tissue grows too large.

In this context, the other options do not accurately describe ectopic pregnancy. Normal implantation occurs within the uterus, which is contrary to the definition of ectopic pregnancy. Multiple gestation refers to the situation where more than one embryo is developing in the uterus simultaneously, typically seen in twins or other multiples, which again does not relate to ectopic pregnancy. Finally, pregnancy complications involving the placenta generally refer to issues such as placenta previa or placental abruption, which are conditions that occur during a normal intrauterine pregnancy, making them irrelevant to the concept of ectopic pregnancy. Therefore, the best description of "ectopic pregnancy" is fetal development outside the uterine cavity.