COMPARISON OF MATERNAL RESPONSE IN FIRST AND SECOND PREGNANCIES IN RELATION TO BABY WEIGHT

Summary

Twenty-one normal women were studied in their first and second pregnancies. The plasma volume continued to expand to term in second pregnancies compared to the slight drop near term in first pregnancies. This may have been due to the postural difference when making the measurements in the two pregnancies. There was a significant correlation between the plasma volume at 30 weeks gestation and birthweight of the baby in both pregnancies. The total protein concentration was the same in both pregnancies, but the serum albumin concentration was significantly lower at 38 weeks gestation in second pregnancies. The total intravascular protein mass was greater at 38 weeks gestation in second pregnancies whereas the intravascular albumin mass remained constant in both pregnancies. The total body water was less but the women's body weight was greater at the corresponding maturity of gestation in second pregnancies, suggesting that there is a change in fat deposition. There was no correlation between total body water and birthweight in second pregnancies. There was no difference between the two pregnancies in the red cell volume, urinary oestriol excretion, serum electrolytes and osmolality.