Open AccessA PROSPECTIVE STUDY OF THE PLACENTAL WEIGHT AND CONTENT OF PROTEIN, RNA AND DNA
Author(s) -
Rolschau John
Publication year - 1978
Publication title -
acta obstetricia et gynecologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.401
H-Index - 102
eISSN - 1600-0412
pISSN - 0001-6349
DOI - 10.1111/aogs.1978.57.s72.28
Subject(s) - placenta , rna , birth weight , nucleic acid , andrology , medicine , dna , pregnancy , obstetrics , gestation , homogenization (climate) , physiology , fetus , biology , genetics , gene , biodiversity , ecology
An investigation was carried out of the placental weight and content of protein, RNA and DNA on 253 placentae. The material was prospectively selected from among mothers with a presumed optimal obstetric outcome, and randomized from 96.7% of the births in the County of Odense. After trimming, freezing and homogenization of the placentae, the content of protein, RNA and DNA were determined spectrophotometrically. It was found that the placental weight rose slightly, approximately 50 g from the 36th to 42nd week. This is not a statistically significant rise. The RNA and DNA ran a parallel course to that of the placental weight during this interval. It is concluded that there is probably no growth of the placenta after the 34th to 36th week, but continued connective tissue formation. The protein content increases throughout the whole pregnancy. After division of the material into primi‐ and multigravidae, it was found that the latter gave birth to 6% heavier infants, while the placental weight and nucleic acid content were increased by 7–10%. This would suggest that a “parity effect” is present in the mother and not in the placenta. A similar division according to the mother's pre‐pregnant weight of more or less than 54 kg, showed that the heavier mothers gave birth to 5% heavier infants, but the difference with regard to the placental weight and content of RNA and DNA was less and non‐significant. This would suggest that the heavy mothers deliver heavier infants for genetical reasons. The material was divided up according to the sex of the infants, and it was found that girls were 1% heavier (NS), while the placental weight of the girls was approximately 5% greater and the DNA content approximately 9% greater. This sex difference which only applies to the placenta is discussed. It was found, following division of the material into 12 parts according to the month of delivery, that the infant weight, placental weight and DNA content were lowest in May–June and highest in August–September. Arguments are put forward that the significant difference in the DNA content of approximately 29% could result from a deficiency of folic acid.