First- and second-trimester hemoglobin levels. Relation to birth weight and gestational age.

The computerized records of 3074 women who were delivered during the period 1987-1990 were analysed. We studied possible relations of birth weight and gestational age to maternal first- and second-trimester hemoglobin levels. Birth weight and gestational age were taken as outcome variables in a multiple stepwise regression analysis, including factors that might interact with hemoglobin levels. A strong independent inverse correlation between the lowest second-trimester hemoglobin and birth weight was observed. First-trimester hemoglobin levels explained little with regard to birth weight, but had a small negative correlation to gestational age. For gestational age < 259 days we found a strong positive correlation between the first- to second-trimester decrease in hemoglobin and birth weight.