Non-linear associations of maternal pre-pregnancy body mass index with risk of stillbirth, infant, and neonatal mortality in over 28 million births in the USA:  a retrospective cohort study

Hannah V Thornton; Rosie P Cornish; Deborah A Lawlor

doi:10.1016/j.eclinm.2023.102351

Non-linear associations of maternal pre-pregnancy body mass index with risk of stillbirth, infant, and neonatal mortality in over 28 million births in the USA: a retrospective cohort study

Hannah V Thornton
, Rosie P Cornish^*
, Deborah A Lawlor

^*Corresponding author for this work

Research output: Contribution to journal › Article (Academic Journal) › peer-review

16 Citations (Scopus)

Abstract

Background
Higher maternal pre-pregnancy body mass index (BMI) has been associated with higher risk of stillbirth, infant and neonatal mortality. Studies exploring underweight have varied in their conclusions. Our aim was to examine the risk of stillbirth, infant and neonatal mortality across the BMI distribution and establish a likely healthy BMI range.
Methods
In this retrospective cohort study, we used publicly available datasets (covering 1st January 2014 to 31st December 2021) from the US National Center for Health Statistics National Vital Statistics System. All births were eligible; analyses included those with non-missing data. Fractional polynomial multivariable logistic regression was used to examine the associations of maternal pre-pregnant BMI with stillbirth (birth with no signs of life at ≥24 weeks), infant mortality (death of a live born baby aged <365 days) and neonatal mortality (death of a live born baby aged <28 days).
Findings
There were 77,896/28,310,154 (2.8 per 1,000 births) stillbirths, 143,620/28,231,807 (5.1 per 1,000 live births) infant deaths and 94,246/28,231,807 (3.3 per 1,000 live births) neonatal deaths among complete cases. Mean (SD) BMI was 27.1 kg/m2 (6.7 kg/m2). We found non-linear associations between BMI and all three outcomes; risk was elevated at both low and high BMIs although, for stillbirth, the increased risk at low BMI was less marked than for infant/neonatal mortality. The lowest risk was at a BMI of 21 kg/m2 for infant and neonatal mortality and 19 kg/m2 for stillbirth.
Interpretation
Public health messaging for preconception and postnatal care should focus on healthy weight to maximise maternal and child health, and not focus solely on maternal overweight or obesity.

Original language	English
Article number	102351
Number of pages	11
Journal	eClinicalMedicine
Volume	66
DOIs	https://doi.org/10.1016/j.eclinm.2023.102351
Publication status	Published - 2 Dec 2023

Bibliographical note

Funding Information:
European Research Council, US National Institute of Health, UK Medical Research Council and National Institute for Health and Care Research.The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007–2013)/ERC Grant Agreement (Grant number 669545; DevelopObese), the US National Institute of Health (R01 DK10324) and the Bristol National Institute for Health and Care Research Biomedical Research Centre. RC and DAL work in a unit that receives support from the UK Medical Research Council (MC_UU_00032/05 and MC_UU_00032/02). DAL is a National Institute for Health and Care Research Senior Investigator (NF-0616-10102). The views presented here are not necessarily those of any funder. This study used publicly available data from the US Vital Statistics office. We thank all the women whose data were contributed to this study, and the healthcare, clinical records and Vital Statistics staff who worked to collate and provide the data.

Funding Information:
The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007–2013)/ ERC Grant Agreement (Grant number 669545 ; DevelopObese), the US National Institute of Health ( R01 DK10324 ) and the Bristol National Institute for Health and Care Research Biomedical Research Centre . RC and DAL work in a unit that receives support from the UK Medical Research Council ( MC_UU_00032/05 and MC_UU_00032/02 ). DAL is a National Institute for Health and Care Research Senior Investigator ( NF-0616-10102 ). The views presented here are not necessarily those of any funder.

Publisher Copyright:
© 2023 The Author(s)

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SDG 3 Good Health and Well-being

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Cite this

@article{3101aff2d3144a1597fba641df2cb6ae,

title = "Non-linear associations of maternal pre-pregnancy body mass index with risk of stillbirth, infant, and neonatal mortality in over 28 million births in the USA: a retrospective cohort study",

abstract = "Background Higher maternal pre-pregnancy body mass index (BMI) has been associated with higher risk of stillbirth, infant and neonatal mortality. Studies exploring underweight have varied in their conclusions. Our aim was to examine the risk of stillbirth, infant and neonatal mortality across the BMI distribution and establish a likely healthy BMI range. Methods In this retrospective cohort study, we used publicly available datasets (covering 1st January 2014 to 31st December 2021) from the US National Center for Health Statistics National Vital Statistics System. All births were eligible; analyses included those with non-missing data. Fractional polynomial multivariable logistic regression was used to examine the associations of maternal pre-pregnant BMI with stillbirth (birth with no signs of life at ≥24 weeks), infant mortality (death of a live born baby aged <365 days) and neonatal mortality (death of a live born baby aged <28 days). Findings There were 77,896/28,310,154 (2.8 per 1,000 births) stillbirths, 143,620/28,231,807 (5.1 per 1,000 live births) infant deaths and 94,246/28,231,807 (3.3 per 1,000 live births) neonatal deaths among complete cases. Mean (SD) BMI was 27.1 kg/m2 (6.7 kg/m2). We found non-linear associations between BMI and all three outcomes; risk was elevated at both low and high BMIs although, for stillbirth, the increased risk at low BMI was less marked than for infant/neonatal mortality. The lowest risk was at a BMI of 21 kg/m2 for infant and neonatal mortality and 19 kg/m2 for stillbirth. Interpretation Public health messaging for preconception and postnatal care should focus on healthy weight to maximise maternal and child health, and not focus solely on maternal overweight or obesity. ",

author = "Thornton, \{Hannah V\} and Cornish, \{Rosie P\} and Lawlor, \{Deborah A\}",

note = "Funding Information: European Research Council, US National Institute of Health, UK Medical Research Council and National Institute for Health and Care Research.The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007–2013)/ERC Grant Agreement (Grant number 669545; DevelopObese), the US National Institute of Health (R01 DK10324) and the Bristol National Institute for Health and Care Research Biomedical Research Centre. RC and DAL work in a unit that receives support from the UK Medical Research Council (MC\_UU\_00032/05 and MC\_UU\_00032/02). DAL is a National Institute for Health and Care Research Senior Investigator (NF-0616-10102). The views presented here are not necessarily those of any funder. This study used publicly available data from the US Vital Statistics office. We thank all the women whose data were contributed to this study, and the healthcare, clinical records and Vital Statistics staff who worked to collate and provide the data. Funding Information: The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007–2013)/ ERC Grant Agreement (Grant number 669545 ; DevelopObese), the US National Institute of Health ( R01 DK10324 ) and the Bristol National Institute for Health and Care Research Biomedical Research Centre . RC and DAL work in a unit that receives support from the UK Medical Research Council ( MC\_UU\_00032/05 and MC\_UU\_00032/02 ). DAL is a National Institute for Health and Care Research Senior Investigator ( NF-0616-10102 ). The views presented here are not necessarily those of any funder. Publisher Copyright: {\textcopyright} 2023 The Author(s)",

year = "2023",

month = dec,

day = "2",

doi = "10.1016/j.eclinm.2023.102351",

language = "English",

volume = "66",

journal = "eClinicalMedicine",

issn = "2589-5370",

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Non-linear associations of maternal pre-pregnancy body mass index with risk of stillbirth, infant, and neonatal mortality in over 28 million births in the USA: a retrospective cohort study. / Thornton, Hannah V; Cornish, Rosie P ; Lawlor, Deborah A.
In: eClinicalMedicine, Vol. 66, 102351, 02.12.2023.

Research output: Contribution to journal › Article (Academic Journal) › peer-review

TY - JOUR

T1 - Non-linear associations of maternal pre-pregnancy body mass index with risk of stillbirth, infant, and neonatal mortality in over 28 million births in the USA

T2 - a retrospective cohort study

AU - Thornton, Hannah V

AU - Cornish, Rosie P

AU - Lawlor, Deborah A

N1 - Funding Information: European Research Council, US National Institute of Health, UK Medical Research Council and National Institute for Health and Care Research.The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007–2013)/ERC Grant Agreement (Grant number 669545; DevelopObese), the US National Institute of Health (R01 DK10324) and the Bristol National Institute for Health and Care Research Biomedical Research Centre. RC and DAL work in a unit that receives support from the UK Medical Research Council (MC_UU_00032/05 and MC_UU_00032/02). DAL is a National Institute for Health and Care Research Senior Investigator (NF-0616-10102). The views presented here are not necessarily those of any funder. This study used publicly available data from the US Vital Statistics office. We thank all the women whose data were contributed to this study, and the healthcare, clinical records and Vital Statistics staff who worked to collate and provide the data. Funding Information: The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007–2013)/ ERC Grant Agreement (Grant number 669545 ; DevelopObese), the US National Institute of Health ( R01 DK10324 ) and the Bristol National Institute for Health and Care Research Biomedical Research Centre . RC and DAL work in a unit that receives support from the UK Medical Research Council ( MC_UU_00032/05 and MC_UU_00032/02 ). DAL is a National Institute for Health and Care Research Senior Investigator ( NF-0616-10102 ). The views presented here are not necessarily those of any funder. Publisher Copyright: © 2023 The Author(s)

PY - 2023/12/2

Y1 - 2023/12/2

N2 - Background Higher maternal pre-pregnancy body mass index (BMI) has been associated with higher risk of stillbirth, infant and neonatal mortality. Studies exploring underweight have varied in their conclusions. Our aim was to examine the risk of stillbirth, infant and neonatal mortality across the BMI distribution and establish a likely healthy BMI range. Methods In this retrospective cohort study, we used publicly available datasets (covering 1st January 2014 to 31st December 2021) from the US National Center for Health Statistics National Vital Statistics System. All births were eligible; analyses included those with non-missing data. Fractional polynomial multivariable logistic regression was used to examine the associations of maternal pre-pregnant BMI with stillbirth (birth with no signs of life at ≥24 weeks), infant mortality (death of a live born baby aged <365 days) and neonatal mortality (death of a live born baby aged <28 days). Findings There were 77,896/28,310,154 (2.8 per 1,000 births) stillbirths, 143,620/28,231,807 (5.1 per 1,000 live births) infant deaths and 94,246/28,231,807 (3.3 per 1,000 live births) neonatal deaths among complete cases. Mean (SD) BMI was 27.1 kg/m2 (6.7 kg/m2). We found non-linear associations between BMI and all three outcomes; risk was elevated at both low and high BMIs although, for stillbirth, the increased risk at low BMI was less marked than for infant/neonatal mortality. The lowest risk was at a BMI of 21 kg/m2 for infant and neonatal mortality and 19 kg/m2 for stillbirth. Interpretation Public health messaging for preconception and postnatal care should focus on healthy weight to maximise maternal and child health, and not focus solely on maternal overweight or obesity.

AB - Background Higher maternal pre-pregnancy body mass index (BMI) has been associated with higher risk of stillbirth, infant and neonatal mortality. Studies exploring underweight have varied in their conclusions. Our aim was to examine the risk of stillbirth, infant and neonatal mortality across the BMI distribution and establish a likely healthy BMI range. Methods In this retrospective cohort study, we used publicly available datasets (covering 1st January 2014 to 31st December 2021) from the US National Center for Health Statistics National Vital Statistics System. All births were eligible; analyses included those with non-missing data. Fractional polynomial multivariable logistic regression was used to examine the associations of maternal pre-pregnant BMI with stillbirth (birth with no signs of life at ≥24 weeks), infant mortality (death of a live born baby aged <365 days) and neonatal mortality (death of a live born baby aged <28 days). Findings There were 77,896/28,310,154 (2.8 per 1,000 births) stillbirths, 143,620/28,231,807 (5.1 per 1,000 live births) infant deaths and 94,246/28,231,807 (3.3 per 1,000 live births) neonatal deaths among complete cases. Mean (SD) BMI was 27.1 kg/m2 (6.7 kg/m2). We found non-linear associations between BMI and all three outcomes; risk was elevated at both low and high BMIs although, for stillbirth, the increased risk at low BMI was less marked than for infant/neonatal mortality. The lowest risk was at a BMI of 21 kg/m2 for infant and neonatal mortality and 19 kg/m2 for stillbirth. Interpretation Public health messaging for preconception and postnatal care should focus on healthy weight to maximise maternal and child health, and not focus solely on maternal overweight or obesity.

U2 - 10.1016/j.eclinm.2023.102351

DO - 10.1016/j.eclinm.2023.102351

M3 - Article (Academic Journal)

C2 - 38125933

SN - 2589-5370

VL - 66

JO - eClinicalMedicine

JF - eClinicalMedicine

M1 - 102351

ER -