STUDY OF THE BIRTH-WEIGHT OF PARENTS EXPERIENCING UNEXPLAINED RECURRENT MISCARRIAGES

Objective To examine birthweight and preterm birth rates in couples with unexplained recurrent miscarriages. Design A case control study. Birth data of couples with recurrent miscarriages were obtained from midwife records. Time and sex-matched births from the same records served as controls. Setting A Regional Hospital in Denmark. Subjects 79 singleborn women with recurrent miscarriages and 60 of their male partners comprised the main study groups. Two control groups comprised 474 female and 360 male singleborn infants who survived day 7 postpartum. Main outcome measures Mean birthweight in the two main study groups and in subgroups with histories of 3, 4 and greater-than-or-equal-to 5 miscarriages. Results The mean birthweight of the women with recurrent miscarriages was 3265 g (SE 70) and in female controls 3414 g (SE 23) (P<0.025). The 17 women with five or more miscarriages had a mean birthweight of 2991 g (SD 140) (P<0.001 compared with controls). Of the women in the study group 10.8% were born preterm compared with 2.9% of the controls (P=0.01). The mean birthweight of the male partners in the study group, 3470 g (SE 68), did not differ significantly from that of 3504 g (SE 31) in the male controls (P<0.5). Conclusions Women suffering unexplained recurrent miscarriages have on average had a significantly lower than normal birthweight themselves, whereas this was not observed in their male partners. This points towards the existence of a birthweight-reducing trait associated with recurrent miscarriages, the trait being manifest only in the woman.