The effects of inbreeding on reproductive outcome have been extensively
studied. Previously it had been considered that inbreeding contributed to increased
mortality and morbidity with detrimental effects on reproductive outcome; however, some
studies have shown only a moderate to slight impact. The fertility of consanguineous
couples and infant and childhood morbidity and mortality in their progeny have also been
extensively studied and numerous reports have concluded that consanguinity is not
associated with either a significant positive or negative effect on fertility. The majority of
studies found that first cousin couples produce more children. In many cases the mean
number of live births to women in consanguineous marriages has been reported as being
higher than that in non-consanguineous unions, although several studies found that mean
fertility rates may be lower in consanguineous couples. Other reports suggested that lower
fertility was possibly due to a failure to initiate pregnancy when the couple shared specific
HLA haplotypes, or because of the expression of deleterious genes acting during early
embryonic or fetal development that resulted in periconceptual losses. In general, higher
total fertility rates have been reported in consanguineous marriages. Reports regarding the
association of consanguinity and fetal wastage are conflicting, with some reporting that the
total prenatal losses were essentially the same for consanguineous and non-consanguineous
couples. A higher prevalence of congenital anomalies in general has been reported among
first cousin couples in all populations.
Keywords: Congenital anomalies, consanguinity, fertility, fetal wastage, human
leukocyte antigen, reproductive outcome.
