Miscarriage is defined as the spontaneous loss of a pregnancy before the fetus reaches viability; it includes all pregnancy losses from the time of conception until 24 weeks of gestation. Early miscarriages are common, occurring in 10–20% of all pregnancies, with 2% of second-trimester pregnancies being miscarried before 24 weeks of gestation. Recurrent miscarriage, defined as the loss of three or more consecutive pregnancies, affects 1% of couples trying to conceive with the chance of having two consecutive miscarriages being 5%. Clinical studies show that 3 in 4 women will have a successful pregnancy with supportive care alone. Therefore, couples should be given reassurance about their chances of a successful pregnancy in the future. In this review we look at the epidemiological factors influencing rates of miscarriage, acquired and inherited thrombophilia, genetic, anatomical, endocrine, immune, infective and male factors for recurrent miscarriage. Despite these potential causes, the majority (around 50%) of recurrent pregnancy losses remain unexplained.
Ecological and Epidemiological Factors Influencing Arbovirus Diversity, Evolution and Spread