The prediction of pregnancy outcome by haemoglobin measurement before 20 weeks` gestation

Relationship between anaemia during pregnancy and preterm delivery

The purpose of this study was to analyse the relationship between preterm delivery and maternal anaemia. This retrospective cohort study was completed with 483 women; 294 of them had a normal delivery and 189 had a preterm delivery. The haemoglobin (Hb) values of all the women participating in the study were measured in the first and second trimesters, and the average Hb values were calculated. The pregnant women participating in the study were divided into three groups, according to their Hb level: those with Hb level <10 g/dl, those with Hb level between 10 and 11 g/dl and those with Hb level >11 g/dl. In crude analysis, women with low Hb levels had an increased rate of preterm delivery (odds ratio, 2.42; 95% CI, 1.07-5.49). Our study provides data that low Hb level is effective in preterm delivery. Impact statement What is already known on this subject? Serum Hb levels have inconsistent associations with a risk of preterm delivery. What the results of this study add? Compared with term delivery Hb levels are lower in preterm delivery. It is necessary to take into account the Hb levels of both the first and second trimester of the pregnancy when describing the pregnancy anaemia. What the implications are of these findings for clinical practice and/or further research? Given these results, physicians should take into account anaemia in pregnancy when considering the risk of a preterm delivery.

Maternal haemoglobin concentration and risk of preterm birth in a Chinese population

The aim was to examine the relationship between maternal haemoglobin (Hb) concentrations and risk of preterm birth by secondary analysis of data from a randomised controlled trial. This analysis included 10,430 women who were at least 20 years old and no more than 20 weeks of gestation. Results revealed neither first- nor second-trimester Hb concentrations were associated with the risk of preterm births. However, the risk of preterm birth increased when the Hb level was low (<130 g/L) in the first but high (≥130 g/L) in the second trimester, regardless of supplement type (iron-containing: AOR: 2.26, 95% CI: 1.37-3.73; non-iron-containing: AOR: 2.16, 95% CI: 1.11-4.21). In conclusion, maternal Hb concentrations were not associated with the risk of preterm birth. A low-Hb level in the first trimester but coupled with a high Hb level in the second was associated with an elevated risk of preterm birth. Impact statement What is already known on this subject: The relationship between maternal Hb concentration and preterm birth remains inconclusive. Some studies have shown an association between a low- or a high-Hb level and an increased risk of preterm birth. Others have not found such an association. Yet others have shown a U-shaped relationship. What do the results of this study add: Overall, maternal Hb concentrations in first or second trimester were not statistically associated with the risk of preterm birth. However, women with a low Hb concentration in the first trimester together with a high Hb concentration in the second trimester had an increased risk of preterm birth, compared to women who had a higher Hb concentration in the first trimester that remained similar during the second trimester. What are the implications are of these findings for clinical practice and/or further research: Our finding helps identify mothers who are at risk of having a preterm delivery. Investigating the underlying clinical causes of the unfavourable change in Hb levels and close follow-up to these women may help improve birth outcomes.

Longitudinal discriminant analysis of hemoglobin level for predicting preeclampsia

Background:

Preeclampsia is one of the most serious complications during pregnancy with important effects on health of mother and fetus that causes maternal and fetal morbidity and mortality. This study was performed to evaluate whether high levels of hemoglobin may increase the risk of preeclampsia.

Objectives:

The present study aimed to predict preeclampsia by the hemoglobin profiles through longitudinal discriminant analysis and comparing the error rate of discrimination in longitudinal and cross sectional data.

Patients and Methods:

In a prospective cohort study from October 2010 to July 2011, 650 pregnant women referred to the prenatal clinic of Milad Hospital in Tehran were evaluated in 3 stages. The hemoglobin level of each woman was measured in the first, second, and third trimester of pregnancy by an expert technician. The subjects were followed up to delivery and preeclampsia was the main outcome under study. The covariance pattern and linear-mixed effects models are common methods that were applied for discriminant analysis of longitudinal data. Also Student t, Mann-Whitney U, and chi-square tests were used for comparing the demographic and clinical characteristics between two groups. Statistical analyses were performed using the SAS software version 9.1.

Results:

The prevalence rate of preeclampsia was 7.2% (47 women). The women with preeclampsia had a higher mean of hemoglobin values and the difference was 0.46 g/dL (P = 0.003). Also the mean of hemoglobin in the first trimester was higher than that of the second trimester, and was lower than that of the third trimester and the differences were significant (P = 0.015 and P < 0.001, respectively). The sensitivity for longitudinal data and cross-sectional data in three trimesters was 90%, 67%, 72%, and 54% and the specificity was 88%, 55%, 63%, and 50%, respectively.

Conclusions:

The levels of hemoglobin can be used to predict preeclampsia and monitoring the pregnant women and its regular measure in 3 trimesters help us to identify women at risk for preeclampsia.

Low first-trimester hemoglobin and low birth weight, preterm birth and small for gestational age newborns

OBJECTIVE

To examine the relationship between first-trimester hemoglobin (Hb) concentration and risk of low birth weight (LBW), preterm birth and small for gestational age (SGA).

METHODS

Data were obtained from a population-based prenatal care program in China. A total of 88,149 women who delivered during 1995-2000 and had their Hb measured in the first trimester were selected as study subjects.

RESULTS

The prevalence of anemia (Hb<110 g/L) was 22.1% in the first trimester. The risk of LBW, preterm birth and SGA was increased steadily with the decrease of first-trimester Hb concentration. After controlling for confounding factors, women with Hb 80-99 g/L had significantly higher risk for LBW (OR=1.44, 95% CI 1.17-1.78), preterm birth (OR=1.34, 95% CI 1.16-1.55) and SGA (OR=1.13, 95% CI 0.98-1.31) than women with Hb 100-119 g/L. No elevated risk was noted for women with Hb> or =120 g/L.

CONCLUSION

Low first-trimester Hb concentration increases the risk of LBW, preterm birth and SGA.