Maternal hemoglobin concentration and adverse pregnancy outcomes at low and moderate altitudes in Peru

Abstract

Objective: To identify associations of maternal hemoglobin (Hb) with perinatal outcomes at low and moderate altitudes in Peru. Methods: Study of records with sequential information using perinatal database system. The study included 295 651 pregnant women with their products. Using multiple logistic regression analysis, we estimated the probability of stillbirths, preterm and small for gestational age (SGA) births associated with maternal Hb levels at low (0–1999 m) and moderate altitudes (2000–2999 m). Results: Maternal Hb decreased as pregnancy progressed from first to third trimester at both altitudes. Hb was higher at moderate than at low altitude (p < 0.001). Risks for stillbirths increased with low maternal Hb (odds ratio [OR]: 1.39 for Hb 9–9.9; OR: 1.84 for Hb 8–8.9; OR: 3.25 for Hb 7–7.9; and OR: 7.8 for Hb <7 g/dl); with Hb higher than 14.5 g/dl (OR: 1.31) and with altitudes ≥2000 m (OR: 1.2). High preterm rates were also observed with low Hbs (OR: 1.16 for Hb 9–9.9; OR: 1.64 for Hb 8–8.9; OR: 2.25 for Hb 7–7.9; and OR:2.87 for Hb<7 g/dl) and with Hb higher than 14.5 g/dl (OR: 1.14). High SGA rates were observed in neonates with maternal Hb of 7–7.9 (OR: 1.35) and <7 g/dl (OR:1.57), and higher than 14.5 g/dl (OR: 1.33), and with moderate altitudes (OR: 1.12). The cut-off points for lower risks of stillbirth and preterm births was 10 g/dl, and for SGA 9 g/dl of hemoglobin. Conclusion: Low and high maternal Hb levels and moderate altitude were independent risk factors for adverse perinatal outcomes.

Keywords::

• Adverse perinatal outcomes
• high maternal hemoglobin
• maternal anemia
• moderate altitude
• preterm births
• small for gestational age
• stillbirths

Acknowledgements

We thank the Ministry of Health and all units in the different study areas of Peru that contributed data to the Perinatal Information System (SIP).

The study was supported by a grant from UNDP/UNFPA/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction at the World Health Organization. The funding sources had no involvement in the design, analysis or reporting of this study.

Declaration of Interest: The authors report no conflict of interest.

Gustavo F. Gonzales conceived the idea. Gustavo F. Gonzales, Carlos E. Carrillo and Vilma Tapia developed the protocol. Gustavo F. Gonzales, Carlos E. Carrillo, Vilma Tapia conceived and designed the cohort study. Gustavo F. Gonzales, Carlos E. Carrillo, Vilma Tapia and Manuel Gasco contributed to an important matter in the conduct of the study, and collection of the data. Vilma Tapia analyzed and interpreted the data and developed the prediction model. Gustavo F. Gonzales drafted the manuscript. All authors critically revised the manuscript for important intellectual content and gave approval of the final submitted version.