Impact of First Trimester Hemoglobin Levels on Pregnancy Outcomes: A Study of 454,815 Women in Chengdu (2019-2023)
- This study analyzed sociodemographic and obstetric characteristics of 454,815 pregnant women.
- Anemia affected 5.8% of participants, with 4.4% having mild anemia, 1.4% moderate anemia, and 0.01% severe anemia.
- Pregnant women with higher Hb levels showed increased rates of gestational diabetes mellitus (GDM) and gestational hypertension disorders (GHD).
Study Overview
Table of Contents
This study analyzed sociodemographic and obstetric characteristics of 454,815 pregnant women. The average age was 29.2 years, and the median gestational age for hemoglobin (Hb) testing was 10.6 weeks. Most participants (96.9%) were Han ethnicity, and 70.9% had rural hukou status. The study found that women with higher Hb concentrations tended to be younger, nulliparous, of Han ethnicity, employed, urban residents, more educated, and had higher prepregnancy BMI.
Anemia Prevalence
The mean Hb concentration was 126.0 g/L. Anemia affected 5.8% of participants, with 4.4% having mild anemia, 1.4% moderate anemia, and 0.01% severe anemia. Anemia risk decreased with age until 26, then increased again past 49 years.
Adverse Pregnancy Outcomes
Pregnant women with higher Hb levels showed increased rates of gestational diabetes mellitus (GDM) and gestational hypertension disorders (GHD). For women with Hb ≥ 140 g/L, 21.3% developed GDM, and 9.7% had GHD. In contrast, only 13.4% with moderate-severe anemia (Hb ≤ 99 g/L) developed GDM, and 5.1% had GHD.
Cesarean sections were most common in the Hb 110–119 g/L group (51.3%). Preterm birth (PTB), low birth weight (LBW), and small for gestational age (SGA) were least frequent in the Hb 120–129 g/L category.
Logistic Regression Results
Logistic regression analysis showed various Hb concentrations increased the odds of adverse outcomes. Compared to the Hb 110–119 g/L reference group:
- Hb ≥ 140 g/L:
- Increased odds of cesarean delivery, LBW, and SGA.
- Hb ≤ 99 g/L:
- Also increased odds for these adverse outcomes.
A U-shaped relationship was observed between Hb concentrations and adverse outcomes, indicating risk at both low and high Hb levels.
Conclusion
Sociodemographic factors and Hb levels predict certain pregnancy outcomes. Women with Hb levels outside the 110–119 g/L range face higher risks for complications such as GDM, GHD, PTB, LBW, and SGA. Understanding these associations can help in managing pregnancy risks effectively.