Pakistan, a nation characterized by profound cultural and genetic diversity, has a high prevalence of both consanguineous marriages and, increasingly, interethnic unions. While the genetic risks of consanguinity are well-documented, the reproductive outcomes of marriages between distinct ethnic groups (e.g., Punjabi with Sindhi, Pashtun with Baloch) remain poorly understood. This review synthesizes literature from human genetics, reproductive immunology, and sociology to explore the hypothesis that interethnic marriages in Pakistan are associated with higher rates of subfertility and infertility compared to intra-ethnic, non-consanguineous marriages. We examine potential roles of genetic incompatibilities (Bateson-Dobzhansky-Muller incompatibilities), immunogenetic mismatches, and compounded socio-cultural stressors. This article highlights a critical research gap, as most studies conflate all non-consanguineous unions, and calls for rigorously controlled investigations to clarify these risks.

Keywords: Intermarriage, Infertility, Pakistan, Ethnicity, Genetics, Consanguinity