Abstract
BACKGROUND: Hemoglobin (Hb) is a modifiable risk factor for adverse pregnancy outcomes. Studies have reported conflicting associations between maternal Hb levels and adverse pregnancy outcomes, including preterm birth (PTB), low birth weight (LBW), and perinatal mortality.
OBJECTIVE: In this study, we aimed to estimate the shape and magnitude of associations between maternal Hb levels in early (7-12 wk gestation) and late pregnancy (27-32 wk gestation) and pregnancy outcomes in a high-income setting.
METHODS: We used data from 2 UK population-based pregnancy cohorts: the Avon Longitudinal Study of Parents and Children (ALSPAC) and Pregnancy Outcome Prediction Study (POPS). We used multivariable logistic regression models to examine the relationship between Hb and pregnancy outcomes, adjusting for maternal age, ethnicity, BMI, smoking status, and parity. Main outcome measures were PTB, LBW, small for gestational age (SGA), pre-eclampsia (PET), and gestational diabetes mellitus (GDM).
RESULTS: Mean Hb in ALSPAC were 12.5 g/dL (SD = 0.90) and 11.2 g/dL (SD = 0.92) in early and late pregnancy, respectively, and 12.7 g/dL (SD = 0.82) and 11.4 g/dL (SD = 0.82) in POPS. In the pooled analysis, there was no evidence of associations between a higher Hb in early pregnancy (7-12 wk gestation) and PTB (OR per 1 g/dL of Hb: 1.09; 95% CI: 0.97, 1.22), LBW (1.12: 0.99, 1.26), and SGA (1.06; 0.97, 1.15). Higher Hb in late pregnancy (27-32 wk gestation) was associated with PTB (1.45: 1.30, 1.62), LBW (1.77: 1.57, 2.01), and SGA (1.45: 1.33, 1.58). Higher Hb in early and late pregnancy was associated with PET in ALSPAC (1.36: 1.12, 1.64) and (1.53: 1.29, 1.82), respectively, but not in POPS (1.17:0.99, 1.37) and (1.03: 0.86, 1.23). There was an association with a higher Hb and GDM in ALSPAC in both early and late pregnancy [(1.51: 1.08, 2.11) and (1.35: 1.01, 1.79), respectively], but not in POPS [(0.98: 0.81, 1.19) and (0.83: 0.68, 1.02)].
CONCLUSIONS: Higher maternal Hb may identify the risk of adverse pregnancy outcomes. Further research is required to investigate if this association is causal and to identify the underlying mechanisms.
| Original language | English |
|---|---|
| Pages (from-to) | 616-624 |
| Number of pages | 9 |
| Journal | American Journal of Clinical Nutrition |
| Volume | 117 |
| Issue number | 3 |
| Early online date | 3 Mar 2023 |
| DOIs | |
| Publication status | Published - 3 Mar 2023 |
Bibliographical note
Funding Information:This study was supported in part by the National Institute for Health Research (NIHR) Cambridge Biomedical Research Centre (Women's Health Theme). The UK Medical Research Council and Welcome (217065/Z/19/Z) and the University of Bristol provided core support for the Avon Longitudinal Study of Parents and Children. This publication is the work of the authors who will serve as guarantors for the contents of this paper. For the purpose of Open Access, the author has applied a CC BY public copyright licence to any Author Accepted Manuscript version arising from this submission. The funders had no involvement in the study design, data collection, analysis or interpretation, article preparation, or the decision to submit the article for publication.
Funding Information:
We thank all the families who took part in this study, the midwives for their help in recruiting them, and the whole ALSPAC team, which includes interviewers, computer and laboratory technicians, clerical workers, research scientists, volunteers, managers, receptionists, and nurses. The authors are also grateful to all participants of the POP study. The author responsibilities were as follows—CB: conceived the study, contributed to designing of the methodology, performed data analysis and data interpretation, and wrote the original draft of the manuscript; GC: contributed to designing the methodology, performed data analysis and data interpretation, and contributed to reviewing and editing of the manuscript; US: contributed to the design of methodology and contributed to draft reviewing and editing; GS: contributed to methodology design and draft reviewing and editing; AF: contributed to study conceptualization and methodology, performed data analysis and data interpretation, and contributed to draft reviewing and editing; and all authors: have read and approved the final manuscript. Outside the scope of this work, within the last 5 y, GS has received research support from Roche Diagnostics Ltd, Illumina, and Sera Prognostics (fetal growth restriction, pre-eclampsia, and preterm birth). GS’s department has received payment from Roche for a talk given by GS (fetal growth restriction). GS received a consultant fee from GSK (preterm birth) and is a member of a data monitoring committee for GSK trials of RSV vaccination in pregnancy. All other authors report no conflicts of interest.
Funding Information:
This study was supported in part by the National Institute for Health Research (NIHR) Cambridge Biomedical Research Centre (Women’s Health Theme). The UK Medical Research Council and Welcome ( 217065/Z/19/Z ) and the University of Bristol provided core support for the Avon Longitudinal Study of Parents and Children. This publication is the work of the authors who will serve as guarantors for the contents of this paper. For the purpose of Open Access, the author has applied a CC BY public copyright licence to any Author Accepted Manuscript version arising from this submission. The funders had no involvement in the study design, data collection, analysis or interpretation, article preparation, or the decision to submit the article for publication.
Publisher Copyright:
© 2022
Keywords
- Child
- Female
- Humans
- Infant, Newborn
- Pregnancy
- Data Analysis
- Diabetes, Gestational
- Longitudinal Studies
- Parity
- Premature Birth
- Prospective Studies
- United Kingdom
- Hemoglobins
Access to Document
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This is the accepted author manuscript (AAM). The final published version (version of record) is available online via Oxford University Press at [https://doi.org/10.1016/j.ajcnut.2022.10.011]. Please refer to any applicable terms of use of the publisher.