RESUMO
Serum placental phosphatase (heat-stable alkaline phosphatase, HSAP) was measured in the following gravidae with normal weight gain: 71 normal weight normal subjects (NWN), 26 overweight normal subjects (OWN), and 28 underweight normal subjects (UWN); and in the following gravidae with excess gain (XsG), small gain (SmG), or weight loss (WtL): 11 NWN-XsG, seven NWN-SmG, seven OWN-SmG, two OWN-XsG, three OWN-WtL, and five UWN-XsG. The NWN regression equation between 31 and 40 weeks was: Y = 0.66X - 18.44. Overweight subjects' HSAP values were typically below and underweight subjects' values were above the regression line, providing that the weight gain was not less than normal in the overweight group or greater than normal in the underweight group. The average difference from the NWN regression line for each subject was designated "deltaHSAP." The differences between the mean delta HSAP values was statistically significant for: NWN versus OWN, NWN versus UWN, OWN versus UWN, NWN-XsG versus NWN-SmG, NWN-SmG, NWN versus NWN-XsG, and OWN versus OWN-WtL. The higher delta HSAP values were associated with relative caloric insufficiency, the lower values with relative caloric excess. A low degree of inverse correlation was found between infant birthweight and delta HSAP (r = -0.37; P less than 0.002).