Maternal urinary metabolic signatures of fetal growth and associated clinical and environmental factors in the INMA study.
BACKGROUND
Maternal metabolism during pregnancy is a major determinant of the intra-uterine environment and fetal outcomes. Herein, we characterize the maternal urinary metabolome throughout pregnancy to identify maternal metabolic signatures of fetal growth in two subcohorts and explain potential sources of variation in metabolic profiles based on lifestyle and clinical data.


METHODS
We used1H nuclear magnetic resonance (NMR) spectroscopy to characterize maternal urine samples collected in the INMA birth cohort at the first (n = 412 and n = 394, respectively, in Gipuzkoa and Sabadell cohorts) and third trimesters of gestation (n = 417 and 469). Metabolic phenotypes that reflected longitudinal intra- and inter-individual variation were used to predict measures of fetal growth and birth weight.


RESULTS
A metabolic shift between the first and third trimesters of gestation was characterized by1H NMR signals arising predominantly from steroid by-products. We identified 10 significant and reproducible metabolic associations in the third trimester with estimated fetal, birth, and placental weight in two independent subcohorts. These included branched-chain amino acids; isoleucine, valine, leucine, alanine and 3 hydroxyisobutyrate (metabolite of valine), which were associated with a significant fetal weight increase at week 34 of up to 2.4 % in Gipuzkoa (P < 0.005) and 1 % in Sabadell (P < 0.05). Other metabolites included pregnancy-related hormone by-products of estrogens and progesterone, and the methyl donor choline. We could explain a total of 48-53 % of the total variance in birth weight of which urine metabolites had an independent predictive power of 12 % adjusting for all other lifestyle/clinical factors. First trimester metabolic phenotypes could not predict reproducibly weight at later stages of development. Physical activity, as well as other modifiable lifestyle/clinical factors, such as coffee consumption, vitamin D intake, and smoking, were identified as potential sources of metabolic variation during pregnancy.


CONCLUSIONS
Significant reproducible maternal urinary metabolic signatures of fetal growth and birth weight are identified for the first time and linked to modifiable lifestyle factors. This novel approach to prenatal screening, combining multiple risk factors, present a great opportunity to personalize pregnancy management and reduce newborn disease risk in later life.
Department of Epidemiology and Biostatistics, Medical Research Council-Public Health England (MRC-PHE) Centre for Environment and Health, School of Public Health, Imperial College London, W2 1PG, London, UK.|Division of Computational and Systems Medicine, Department of Surgery and Cancer, Imperial College London, SW7 2AZ, London, UK.
Léa
L
Maitre
ISGlobal, Centre for Research in Environmental Epidemiology (CREAL), 08003, Barcelona, Spain.|Universitat Pompeu Fabra UPF, 08002, Barcelona, Spain.|CIBER Epidemiología y Salud Pública CIBERESP, 28029, Madrid, Spain.|Municipal Institute of Medical Research IMIM-Hospital del Mar, 08003, Barcelona, Spain.
Cristina M
CM
Villanueva
MRC-NIHR National Phenome Centre, Department of Surgery and Cancer, Imperial College London, IRDB Building, Du Cane Road, W12 0NN, London, UK.
Matthew R
MR
Lewis
CIBER Epidemiología y Salud Pública CIBERESP, 28029, Madrid, Spain.|Public Health Division of Gipuzkoa, Basque Government, 20013, San Sebastián, Spain.|Health Research Institute, Biodonostia, 20013, San Sebastián, Spain.
Jesús
J
Ibarluzea
CIBER Epidemiología y Salud Pública CIBERESP, 28029, Madrid, Spain.|Public Health Division of Gipuzkoa, Basque Government, 20013, San Sebastián, Spain.|Health Research Institute, Biodonostia, 20013, San Sebastián, Spain.
Loreto
L
Santa-Marina
ISGlobal, Centre for Research in Environmental Epidemiology (CREAL), 08003, Barcelona, Spain.|Universitat Pompeu Fabra UPF, 08002, Barcelona, Spain.|CIBER Epidemiología y Salud Pública CIBERESP, 28029, Madrid, Spain.|Municipal Institute of Medical Research IMIM-Hospital del Mar, 08003, Barcelona, Spain.
Martine
M
Vrijheid
ISGlobal, Centre for Research in Environmental Epidemiology (CREAL), 08003, Barcelona, Spain.|Universitat Pompeu Fabra UPF, 08002, Barcelona, Spain.|CIBER Epidemiología y Salud Pública CIBERESP, 28029, Madrid, Spain.|Municipal Institute of Medical Research IMIM-Hospital del Mar, 08003, Barcelona, Spain.
Jordi
J
Sunyer
Division of Computational and Systems Medicine, Department of Surgery and Cancer, Imperial College London, SW7 2AZ, London, UK. m.coen@imperial.ac.uk.
Muireann
M
Coen
Department of Epidemiology and Biostatistics, Medical Research Council-Public Health England (MRC-PHE) Centre for Environment and Health, School of Public Health, Imperial College London, W2 1PG, London, UK. m.toledano@imperial.ac.uk.
Mireille B
MB
Toledano
D000328:Adult; D001724:Birth Weight; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D020567:Fetal Weight / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn; D008019:Life Style; D019906:Nuclear Magnetic Resonance, Biomolecular; D011247:Pregnancy / Q000378:metabolism*
Birth weight; Exposome; Fetal growth; In utero environment; Metabolomics; Metabonomics; NMR; Pregnancy