Temporal trends of hemoglobin among pregnant women: The Mutaba'ah study

Low hemoglobin (Hb) level is a leading cause of many adverse pregnancy outcomes. Patterns of changes in Hb levels during pregnancy are not well understood.

This study estimated Hb levels, described its changing patterns across gestational trimesters, and identified factors associated with these changes among pregnant women.

Data from the ongoing maternal and child health cohort study-The Mutaba'ah Study, was used (N = 1,120). KML machine learning algorithm was applied to identify three distinct cluster trajectories of Hb levels between the first and the third trimesters. Descriptive statistics were used to profile the study participants. Multinomial multivariable logistic regression was employed to identify factors associated with change patterns in Hb levels.

The three identified clusters-A, B and C-had, respectively, median Hb levels (g/L) of 123, 118, and 104 in the first trimester and 119, 100, and 108 in the third trimester. Cluster 'A' maintained average normal Hb levels in both trimesters. Cluster 'B', on average, experienced a decrease in Hb levels below the normal range during the third trimester. Cluster 'C' showed increased Hb levels in the third trimester but remained, on average, below the normal range in both trimesters. Pregnant women with higher gravida, diabetes mellitus (type 1 or 2), nulliparity or lower level of education were more likely to be in cluster 'B' than the normal cluster 'A'. Pregnant women who reported using iron supplements before pregnancy or those with low levels of education. were more likely to be in cluster 'C' than the normal cluster 'A'.

The majority of pregnant women experienced low Hb levels during pregnancy. Changes in Hb levels during pregnancy were associated with parity, gravida, use of iron before pregnancy, and the presence of diabetes mellitus (type 1 or 2).