HEMOGLOBIN LEVELS DURING TWIN VS SINGLETON PREGNANCIES - PARITY MAKESTHE DIFFERENCE

A retrospective, case-control study of 200 consecutive twin and single ton gestations matched for parity was conducted to challenge the hypot hesis that lower hemoglobin values appear more often during twin gesta tions. The database consisted of hemoglobin levels recorded during eac h trimester. Comparisons were made between the mean hemoglobin levels and incidence of values > 11, 9-11 and < 9 g/dL. Significantly lower m ean (+/- SD) hemoglobin values were observed during the first (11.94 /- 1.1 vs. 12.17 +/- 1.0, P = .026) and second (11.1 +/- 1.0 vs. 11.48 +/- 0.9, P = .00001) trimesters in twin vs. singleton pregnancies, re spectively. The differences resulted from lower values in multiparas w ith twins as compared with their singleton-pregnancy controls (11.8 +/ - 1.2 vs. 12.2 +/- 0.9, P = .015, for the first trimester and 11.0 +/- 1.0 vs. 11.5 +/- 0.9, P = .0001, for the second trimester). During th e second trimester, the lower incidence of values > 11 g/dL (P = .005, odds ratio = .475, 95% confidence interval = .31-.73) and higher inci dence of values between 9 and 11 g/dL (P = .0008, odds ratio = 2.06, 9 5% confidence interval = 1.34-3.19) may account for the significant di fferences in mean values. There were no differences between third-trim ester values, between multiparas in both groups or between nulliparas and multiparas in each group. We conclude that the lower hemoglobin le vels in twin gestations were associated with multiparty and were stati stically significant during the first and second trimesters. This subg roup of twin pregnancies may benefit from further research and possibl y from closer hematologic care and monitored iron supplementation.