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Miscarriage (previously known as spontaneous abortion) describes the spontaneous discharge of the gestational sac before the fetus is viable. Previously this applied to foetal loss up to 28 weeks gestation but since October 1992, it applies to losses up to 24 weeks. Spontaneous abortion is the process described by the lay public as miscarriage.
Miscarriages occur in up to 10-20% of clinical pregnancies (1). Majority is seen before the thirteenth week (2).
Most of the pregnancies end up as miscarriages even before a woman recognizes that she is pregnant since signs of miscarriage such as bleeding (usually with some abdominal pain and cramping) is mistakenly regarded as heavy or late menses (3).
Increasing maternal age is associated with increased foetal loss.
NICE state with respect to threatened miscarriage: