Circumvallate placenta and intrauterine growth retardation.

A study has been made of a prospectively selected material of circumvallate placentae; the latter being defined as an elevated edge of more than 50% of the circumference. The material consists of 447 placentae from liveborn singleton infants, where 287 were from exemplary pregnancies, and 160 from births with a gestational age (GA) of less than 266 days and/or a birth weight of less than 2750 g. The material was prospectively randomized. It was divided into clinical groups according to the GA and under-weight. Nineteen circumvallate placentae were found. Among these were more multigravidae and more with pre-gestational menstrual irregularity than expected. The number of antepartum haemorrhages was as expected. There were more premature infants, premature under-weight infants and under-weight infants than expected. Nine of the 20 premature under-weight infants in the material had circumvallate placenta. In relation to a previously published basic material, it was found that the birth weight, and placental content of RNA and DNA were significantly reduced. It is concluded that placentae with more than 50% circumvallation are associated with prematurity and under-weight, as well as a placenta with fewer cells than normal. The genesis of the anomaly is discussed.