Association between newborn birth weight and the risk of postpartum maternal venous thromboembolism: a population-based case-control study.
BACKGROUND
Postpartum venous thromboembolism (VTE) is a potentially fatal and preventable event leading to substantial short- and long-term morbidity. We sought to evaluate whether the delivery of term newborns of low or high birth weight was associated with greater risks of VTE.


RESULTS
In a population-based case-control study conducted in Washington State from 1987 through 2011, cases of hospitalized VTE within 3 months of delivery were identified by using selected International Classification of Diseases, Ninth Revision, Clinical Modification codes. Controls were randomly selected postpartum women without VTE, matched on birth year. Birth weight and other maternal and pregnancy characteristics were extracted from birth certificate data. Among term live singleton deliveries, we compared the risk of VTE for mothers of newborns of low and high birth weights (<2500 g and >4000 g, respectively) versus mothers of newborns of normal birth weight (2500-4000 g). Logistic regression models were adjusted for maternal age, race, education, body mass index, parity, delivery methods, gestational length, smoking, gestational diabetes mellitus, and preeclampsia. Patients with VTE (n=547) were older, had a higher body mass index, and experienced more pregnancy-related complications than controls (n=9482). In comparison with mothers of newborns with normal birth weight, mothers of newborns with low birth weight had a 3-fold increased risk of VTE, which persisted after multivariable adjustment (odds ratio, 2.98; 95% confidence interval, 1.80-4.93). Mothers of newborns with high birth weight had only a slightly increased risk of VTE, which was attenuated after multivariable adjustment (odds ratio, 1.26; 95% confidence interval, 0.99-1.61).


CONCLUSIONS
The delivery of a newborn with low birth weight is associated with a 3-fold increased risk of maternal postpartum VTE. This should be considered when assessing VTE risk at delivery.
From Division of Angiology and Haemostasis, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland (M.B., H.B.); Department of Epidemiology, University of Washington, Seattle (M.B., L.B.H., N.L.S.); Division of Respirology, Department of Medicine, St. Paul's Hospital, Vancouver, British Columbia, Canada (B.S.Q.); Group Health Research Institute, Group Health Cooperative, Seattle, WA (N.L.S.); and Seattle Epidemiologic Research and Information Center, Department of Veterans Affairs Office of Research and Development, Seattle, WA (N.L.S.). marc.blondon@hcuge.ch.
Marc
M
Blondon
From Division of Angiology and Haemostasis, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland (M.B., H.B.); Department of Epidemiology, University of Washington, Seattle (M.B., L.B.H., N.L.S.); Division of Respirology, Department of Medicine, St. Paul's Hospital, Vancouver, British Columbia, Canada (B.S.Q.); Group Health Research Institute, Group Health Cooperative, Seattle, WA (N.L.S.); and Seattle Epidemiologic Research and Information Center, Department of Veterans Affairs Office of Research and Development, Seattle, WA (N.L.S.).
Bradley S
BS
Quon
From Division of Angiology and Haemostasis, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland (M.B., H.B.); Department of Epidemiology, University of Washington, Seattle (M.B., L.B.H., N.L.S.); Division of Respirology, Department of Medicine, St. Paul's Hospital, Vancouver, British Columbia, Canada (B.S.Q.); Group Health Research Institute, Group Health Cooperative, Seattle, WA (N.L.S.); and Seattle Epidemiologic Research and Information Center, Department of Veterans Affairs Office of Research and Development, Seattle, WA (N.L.S.).
Laura B
LB
Harrington
From Division of Angiology and Haemostasis, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland (M.B., H.B.); Department of Epidemiology, University of Washington, Seattle (M.B., L.B.H., N.L.S.); Division of Respirology, Department of Medicine, St. Paul's Hospital, Vancouver, British Columbia, Canada (B.S.Q.); Group Health Research Institute, Group Health Cooperative, Seattle, WA (N.L.S.); and Seattle Epidemiologic Research and Information Center, Department of Veterans Affairs Office of Research and Development, Seattle, WA (N.L.S.).
Henri
H
Bounameaux
From Division of Angiology and Haemostasis, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland (M.B., H.B.); Department of Epidemiology, University of Washington, Seattle (M.B., L.B.H., N.L.S.); Division of Respirology, Department of Medicine, St. Paul's Hospital, Vancouver, British Columbia, Canada (B.S.Q.); Group Health Research Institute, Group Health Cooperative, Seattle, WA (N.L.S.); and Seattle Epidemiologic Research and Information Center, Department of Veterans Affairs Office of Research and Development, Seattle, WA (N.L.S.).
Nicholas L
NL
Smith
D000328:Adult; D001724:Birth Weight; D016022:Case-Control Studies; D002585:Cesarean Section / Q000706:statistics & numerical data; D015986:Confounding Factors, Epidemiologic; D036861:Delivery, Obstetric; D005260:Female; D005865:Gestational Age; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D007231:Infant, Newborn; D016015:Logistic Models; D008423:Maternal Age; D010298:Parity; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology; D011644:Puerperal Disorders / Q000453:epidemiology*; D012189:Retrospective Studies; D012306:Risk; D012307:Risk Factors; D012494:Sampling Studies; D019851:Thrombophilia / Q000453:epidemiology; D054556:Venous Thromboembolism / Q000453:epidemiology*; D014861:Washington / Q000453:epidemiology; D055815:Young Adult
embolism; epidemiology; pregnancy; risk factors; thrombosis