[Hemoglobin concentration prior to the 20th week of pregnancy correlated with complications in the third trimester]

The haemodynamic changes in pregnancy result in decrease in haemoglobin and haematocrit. It has previously been demonstrated that absence of this decrease or even increase in the haemoglobin concentration (Hb) and haematocrit (Hct) values measured in the third trimester or late in the second trimester can be correlated to increased risk of development of hypertension, pre-eclampsia and intrauterine growth retardation. In the present investigation, the authors have investigated whether the abovementioned complications of pregnancy can also be correlated to high Hb and high Hct measured early in the third trimester. The investigation included 373 healthy pregnant women, 46 of whom had Hb greater than or equal to 8.3 mmol/l in the 13th-19th weeks. Complications of pregnancy occurred in 17.4% of the 46 women. Among the remaining 327 pregnant women with Hb less than 8.3 mmol/l, complications of pregnancy were observed in only 5.8%. This difference is significant. The blood volume increases by approximately 1.5 litre during pregnancy. The plasma volume increases by 50% from the seventh to the 32nd week and thereafter remains constant until delivery. The erythrocyte volume increases first from approximately the 16th week and increases by a total of 25%. The early increase in plasma volume results in a decrease in the haemoglobin concentration (Hb) and in the haematocrit (Hct) value. During the third trimester, Hb and Hct increase again as a result of the increased erythrocyte volume. A positive correlation has been demonstrated between the magnitude of the plasma volume in the third trimester and the birth weight and a negative correlation between Hb in the third trimester and the birth weight.(ABSTRACT TRUNCATED AT 250 WORDS)