Maternal Haemoglobin and Haematocrit During Pregnancy and Stillbirth Risk: A Prospective, Population-Based Birth...

Area of Science:

• Obstetrics and Gynecology
• Maternal-Fetal Medicine
• Public Health

Background:

• Maternal anemia is a global health concern linked to adverse pregnancy outcomes.
• The impact of high maternal hemoglobin (Hb) and hematocrit (Hct) on stillbirth risk is less understood.

Purpose of the Study:

• To investigate the dose-response relationship between dynamic changes in maternal Hb and Hct levels across trimesters and stillbirth risk.

Main Methods:

• Prospective, longitudinal China Birth Cohort Study (CBCS) (2018-2022) involving 142,715 women.
• Modified Poisson regression models assessed associations between Hb/Hct, haemodilution, and stillbirth.

Main Results:

• Maternal anemia (Hb 70-99 g/L or Hct <33% in the first trimester) significantly increased stillbirth risk (aRR 2.45 and 1.63, respectively).
• A U-shaped association was observed, with both low and high Hb/Hct levels linked to increased stillbirth risk.
• Excessive hemoglobin dilution or concentration across trimesters also elevated stillbirth risk, particularly between the first and second trimesters.

Conclusions:

• Clinical attention is required for both low and high extremes of maternal Hb/Hct levels.
• Monitoring physiological haemodilution is important in mid-to-late pregnancy to improve pregnancy outcomes.