Consanguinity, spousal age at marriage and fertility in seven Pakistani Punjab cities.

A retrospective study was conducted on spousal age at marriage, time to first birth and total pregnancies in the populations of seven cities in the Pakistani province of Punjab. Consanguineous marriages were strongly favoured with coefficients of inbreeding (F) for the present generation ranging from 0.0236 to 0.0286. Male and female ages at marriage were younger in consanguineous unions and spousal age differences smaller than in their non-consanguineous counterparts. Time elapsed from marriage to first birth tended to be longer in consanguineous unions but, in general, they had more pregnancies. As consanguinity has been shown to be associated with increased ante- and postnatal mortality in these communities, reproductive compensation provides a credible explanation for the apparent enhanced fertility with inbreeding. However, the data equally could be interpreted in terms of greater reproductive span and/or biosocial compatibility of the consanguineous unions.