Terminology
Very early spontaneous abortions—those that occur before the sixth week LMP (since the woman's last menstrual period)—sometimes are termed early pregnancy loss or chemical pregnancy. Those that occur after the sixth week post-LMP are medically termed clinical spontaneous abortion.
In medical (and veterinary) contexts, the technical term "abortion" refers to any process by which a pregnancy ends with the death and removal or expulsion of the fetus, regardless of whether it is spontaneous or intentionally induced. Many women who have had miscarriages, however, object to the term "abortion" in connection with their experience, because in everyday English the word is strongly associated with induced abortions. In recent years there has been discussion in the medical community about avoiding the use of this term in favor of the term "miscarriage". In 2005 the European Society for Human Reproduction and Embryology (ESHRE) published a paper aiming to facilitate a revision of nomenclature used to describe early pregnancy events.
Labour resulting in live birth before the 37th week of pregnancy is termed "premature birth", even if the infant dies shortly afterward. The limit of viability at which 50% of fetuses survive longterm is around 24 weeks, with moderate or major neurological disability dropping to 50% only by 26 weeks. Although long-term survival has never been reported for infants born from pregnancy shorter than 21 weeks and 5 days, fetuses born as early as the 16th week of pregnancy may sometimes live for some minutes after birth.
A fetus that dies while in the uterus after about the 20–24th week of pregnancy may be termed a "stillbirth"; the precise gestational age definition varies by country. Premature births or stillbirths are not generally considered "miscarriages", though usage of the terms and causes of these events may overlap. Another term for this has been coined, intrauterine fetal demise (IUFD).
Read more about this topic: Miscarriage