Tohoku J. Exp. Med., 2025 May, 266(1)
Association Between the Number of Deliveries and Cognitive Impairment Considering the Presence of Subclinical Cerebrovascular Diseases: The Ohasama Study
Teiichiro Yamazaki,1 Kyoko Nomura,1,2 Michihiro Satoh,3,4 Azusa Hara,5 Megumi Tsubota-Utsugi,2 Takahisa Murakami,3,4,6 Kei Asayama,2,7 Yukako Tatsumi,2 Yuki Kobayashi,8 Takuo Hirose,9 Ryusuke Inoue,10 Tomoko Totsune,11 Masahiro Kikuya,2,4 Hirohito Metoki,3,4,7 Atsushi Hozawa,4,12 Yutaka Imai7 and Takayoshi Ohkubo2,7
1Department of Environmental Health Science and Public Health, Akita University Graduate School of Medicine, Akita, Akita, Japan
2Department of Hygiene and Public Health, Teikyo University School of Medicine, Tokyo, Japan
3Division of Public Health, Hygiene and Epidemiology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
4Department of Preventive Medicine and Epidemiology, Tohoku Medical Megabank Organization, Tohoku University, Sendai, Miyagi, Japan
5Division of Drug Development and Regulatory Science, Faculty of Pharmacy, Keio University, Tokyo, Japan
6Division of Aging and Geriatric Dentistry, Department of Rehabilitation Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Miyagi, Japan
7Tohoku Institute for Management of Blood Pressure, Sendai, Miyagi, Japan
8Department of Cardiovascular Medicine, Akita University Graduate School of Medicine, Akita, Akita, Japan
9Division of Integrative Renal Replacement Therapy, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
10Medical Information Technology Center, Tohoku University Hospital, Sendai, Miyagi, Japan
11Department of Aging Research and Geriatric Medicine, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Miyagi, Japan
12Division of Epidemiology, School of Public Health, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
Although the association between the number of deliveries and cognitive impairment has been previously examined, the influence of subclinical cerebrovascular diseases (SCDs), such as silent cerebrovascular lesions and carotid atherosclerosis, on this association remains unclear. This cross-sectional study aimed to examine whether SCDs mediated the association between the number of deliveries and cognitive impairment. Among 627 Japanese women with a mean age of 73 years, the number of deliveries was collected in the 1998 survey and classified into four groups (0-1, 2, 3, ≥ 4), with two deliveries as the reference. At the annual comprehensive medical examinations, cognitive function was assessed using the Mini-Mental State Examination (MMSE), and SCDs were evaluated using brain magnetic resonance imaging and ultrasonography. Each participant’s latest data on these variables and covariates between 1992 and 2018 were used. MMSE scores were divided into three ordinal categories: ≥ 28 (normal), 24-27 (mild cognitive impairment; MCI), and ≤ 23 (severe cognitive impairment). Ordinal logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for cognitive impairment. The ORs for cognitive impairment associated with the number of deliveries were 2.13 (95% CI, 1.21-3.76) in the lowest (0-1) group and 1.45 (0.95-2.23) in the highest (≥ 4) group. These association estimates remained similar after adjusting for SCDs but were weaker in the more recent birth year group. We demonstrated a U-shaped association between the number of deliveries and cognitive impairment, independent of SCDs, and the cohort effect confounded the association.
Key words —— atherosclerosis; cerebrovascular disease; cognitive impairment; delivery; women’s health
© 2025 Tohoku University Medical Press
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Tohoku J. Exp. Med., 2025 May, 266(1), 69-79.
Correspondence: Kyoko Nomura, Department of Environmental Health Science and Public Health, Akita University Graduate School of Medicine, 1-1-1 Hondo, Akita, Akita 010-8543, Japan.
e-mail: knomura@med.akita-u.ac.jp