Effect of inbreeding on weight gain of offspring from birth to 12 months after birth: a study from Iran.

Consanguinity, the marriage between relatives, has been associated with adverse child health outcomes. The objective of the present study was to assess the effect of consanguinity on offspring weight gain from birth to 12 months after birth. Data were collected on 250 consecutive live-born singleton newborns referred to a local health centre in Shiraz (Fars province, southern Iran). Collected data covered socio-demographic characteristics (such as parental age at delivery and parental education), sex, birth order, weights from birth to 12 months after birth and consanguinity of marriages of parents. Considering the low prevalence of double first cousin, first cousin once removed, second cousin, and beyond second cousin marriages, only first cousin and unrelated marriages were included in the study. The study population consisted of a total of 207 newborns (57 offspring of first cousins, 150 offspring of unrelated marriages). Based on the results of repeated measurements analysis of variance, weight gain was associated with type of marriage (p=0.018), sex of offspring (p=0.001) and paternal education (p<0.001). There was no interaction between type of marriage and sex (p=0.831). Birth weight was not affected by type of marriage (p=0.46). There was significant interaction between inbreeding and time (p=0.034). Offspring of consanguineous marriages showed lower weight gain in comparison with those of unrelated marriages during 3-12 months after birth.