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Table 1 shows the baseline characteristics of participants stratified by parity. The study population consisted of women with parity of zero (9.1%), one (72.9%), two (13.0%), and three or more (5.0%). There was a significant increase in age with parity (P < 0.001). Multiple lifestyle factors, including current smoking, alcohol use, and physical activity, exhibited a significant difference across the parity groups (all with P < 0.001). Higher proportion of postmenopausal status and use of contraceptive drugs was associated with increasing parity (both with P < 0.001). Socioeconomic status, measured using education level and mean equivalent household income, also demonstrated a statistical difference among the parity groups (both with P < 0.001).
Characteristics Overall Parity group P value 0 1 2 ≥ 3 Number, n (%) 5,674 513 (9.1) 4,138 (72.9) 739 (13.0) 284 (5.0) Age, year 45.4 ± 12.7 28.2 ± 6.2 43.7 ± 9.7 58.5 ± 8.8 67.3 ± 8.0 < 0.001 Age at menopause, year 49.8 ± 4.0 44.4 ± 7.3 49.5 ± 4.0 50.3 ± 3.7 50.0 ± 4.3 < 0.001 Postmenopause, n (%) 1,844 (32.5) 5 (1.0) 1,024 (24.8) 564 (76.3) 251 (88.4) < 0.001 Married, n (%) 5,311 (93.6) 292 (56.9) 4,042 (97.7) 714 (96.6) 263 (92.6) < 0.001 Current smoking, n (%) 120 (2.1) 5 (1.0) 75 (1.8) 24 (3.3) 16 (5.6) < 0.001 Alcohol use, n (%) 203 (3.6) 29 (5.7) 154 (3.7) 19 (2.6) 1 (0.4) < 0.001 Antihypertensive medication, n (%) 659 (11.6) 2 (0.4) 336 (8.1) 214 (29.0) 107 (37.7) < 0.001 Insulin or oral hypoglycemic drug, n (%) 206 (3.6) 1 (0.2) 109 (2.6) 70 (9.5) 26 (9.2) < 0.001 Antilipemic agent, n (%) 81 (1.4) 0 45 (1.1) 19 (2.6) 17 (6.0) < 0.001 Oral contraceptives, n (%) 148 (2.6) 4 (0.8) 91 (2.2) 33 (4.5) 20 (7.0) < 0.001 Estrogen replacement therapy, n (%) 35 (0.6) 1 (0.2) 27 (0.7) 5 (0.7) 2 (0.7) 0.647 Physical activity, n (%) < 0.001 Inactive 2,017 (35.6) 178 (34.7) 1,513 (36.6) 238 (32.2) 88 (31.0) Moderate active 1,062 (18.7) 103 (20.1) 829 (20.0) 86 (11.6) 44 (15.5) Active 2,595 (45.7) 232 (45.2) 1,796 (43.4) 415 (56.2) 152 (53.5) Education level, n (%) < 0.001 Illiteracy/primary school 319 (5.6) 1 (0.2) 86 (2.1) 148 (20.0) 84 (29.6) Middle/high school 2,705 (47.7) 73 (14.2) 1,960 (47.4) 501 (67.8) 171 (60.2) College or above 2,650 (46.7) 439 (85.6) 2,092 (50.5) 90 (12.2) 29 (10.2) Income, ¥/month, n (%) < 0.001 ≤ 3,000 3,194 (56.3) 159 (31.0) 2,221 (53.7) 584 (79.0) 230 (81.0) 3,001–5,000 2,153 (38.0) 304 (59.3) 1,667 (40.3) 134 (18.1) 48 (16.9) > 5,000 327 (5.7) 50 (9.7) 250 (6.0) 21 (2.9) 6 (2.1) Table 1. Baseline characteristics of participants stratified by parity
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Figure 2 shows the prevalence of MetS and its components according to parity. Among the parity groups, nulliparous women had the lowest prevalence, and those with parity of three or more had the highest prevalence of abdominal obesity (81%), elevated fasting glucose levels (21%), high blood pressure (75%), elevated triglyceride levels (43%), and MetS (44%). The prevalence of MetS and its components appeared to increase progressively with parity (all with P < 0.001, Figure 2). However, a similar pattern was not observed for low HDL cholesterol levels (P = 0.119), where nulliparous women had the highest prevalence of 11.7%. Overall, an elevated fasting glucose level was the least prevalent component in our study cohort, and abdominal obesity was the most prevalent component.
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As depicted in Figure 3, there was no association between parity and low HDL cholesterol levels. Regarding the other four components and MetS, there was an increasing trend of ORs
among the parity groups. Compared with women with parity of one, nulliparous women had significantly decreased ORs in all models. Women with parity of two had statistically significant odds of abdominal obesity (OR = 1.45, 95% CI: 1.17–1.81, P < 0.001), high blood pressure (OR = 1.26, 95% CI: 1.03–1.54, P = 0.025), elevated fasting glucose levels (OR = 1.36, 95% CI: 1.03–1.79, P = 0.029), and MetS (OR = 1.39, 95% CI: 1.13–1.73, P = 0.002), and those with parity of three or more had statistically significant odds of elevated triglyceride levels (OR = 1.42, 95% CI: 1.04–1.94, P = 0.027) and MetS (OR = 1.50, 95% CI: 1.10–2.05, P = 0.011) after complete adjustment for age, postmenopausal status, marital status, current smoking, alcohol use, oral contraceptive use, physical activity, education level, and income (Supplementary Table S1 available in www.besjournal.com). Figure 3. The associations between parity and metabolic syndrome and its components. Model 1: unadjusted. Model 2: adjusted for age. Model 3: adjusted for age, postmenopausal status, marital status, current smoking, alcohol use, oral contraceptive use, physical activity, education level, and income.
Parity Abdominal obesity Elevated triglycerides Elevated fasting glucose Low HDL cholesterol High blood pressure Metabolic syndrome OR
(95% CI)P OR
(95% CI)P OR
(95% CI)P OR
(95% CI)P OR
(95% CI)P OR
(95% CI)P Model 1 0 0.34
(0.28—0.41)< 0.001 0.47
(0.36—0.63)< 0.001 0.16
(0.07—0.37)< 0.001 1.27
(0.95—1.69)0.109 0.33
(0.25—0.43)< 0.001 0.35
(0.24—0.51)< 0.001 1 1 1 1 1 1 1 2 2.82
(2.34—3.39)< 0.001 2.00
(1.69—2.37)< 0.001 3.27
(2.63—4.08)< 0.001 1.19
(0.93—1.54)0.171 3.61
(3.07—4.25)< 0.001 3.01
(2.53—3.58)< 0.001 ≥ 3 3.16
(2.34—4.27)< 0.001 2.81
(2.19—3.59)< 0.001 3.80
(2.79—5.17)< 0.001 0.76
(0.48—1.21)0.246 6.47
(4.90—8.54)< 0.001 4.37
(3.41—5.61)< 0.001 Model 2 0 0.34
(0.28—0.42)< 0.001 0.48
(0.36—0.64)< 0.001 0.17
(0.08—0.39)< 0.001 1.28
(0.96—1.71)0.097 0.35
(0.27—0.45)< 0.001 0.37
(0.25—0.54)< 0.001 1 1 1 1 1 1 1 2 2.14
(1.74—2.63)< 0.001 1.62
(1.33—1.98)< 0.001 1.91
(1.45—2.51)< 0.001 1.07
(0.80—1.44)0.634 2.01
(1.67—2.42)< 0.001 1.84
(1.49—2.27)< 0.001 ≥ 3 1.83
(1.29—2.61)< 0.001 1.94
(1.43—2.63)< 0.001 1.57
(1.06—2.32)0.023 0.64
(0.37—1.08)0.093 2.03
(1.45—2.82)< 0.001 1.89
(1.38—2.56)< 0.001 Model 3 0 0.50
(0.40—0.63)< 0.001 0.72
(0.53—1.00)0.048 0.24
(0.10—0.57)0.001 1.09
(0.78—1.53)0.619 0.52
(0.38—0.70)< 0.001 0.45
(0.30—0.68)< 0.001 1 1 1 1 1 1 1 2 1.45
(1.17—1.81)< 0.001 1.15
(0.93—1.41)0.196 1.36
(1.03—1.79)0.029 1.11
(0.81—1.53)0.507 1.26
(1.03—1.54)0.025 1.39
(1.13—1.73)0.002 ≥ 3 1.30
(0.90—1.87)0.167 1.42
(1.04—1.94)0.027 1.20
(0.81—1.77)0.362 0.62
(0.36—1.07)0.084 1.37
(0.97—1.94)0.071 1.50
(1.10—2.05)0.011 Note. Model 1: unadjusted. Model 2: adjusted for age. Model 3: adjusted for age, postmenopause, marital status, current smoking, alcohol use, oral contraceptives, physical activity, education level and income. Table S1. Adjusted ORs for the associations between parity and the metabolic syndrome and its components
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As shown in Table 2, subgroup analyses for the associations between parity and MetS and its components were performed according to BMI and age. BMI was subdivided by 25, age was subdivided by the median, and parity was included as a categorical variable.
Variables BMI* Age# ≤ 25 kg/m2 > 25 kg/m2 P-interaction ≤ 45 > 45 P-interaction Abdominal obesity 0.152 0.442 0 0.48 (0.37–0.64) 1.10 (0.45–2.70) 0.53 (0.41–0.69) 0.86 (0.30–2.46) 1 1 1 1 1 2 1.32 (1.02–1.72) 2.41 (1.19–4.89) 1.03 (0.61–1.75) 1.58 (1.26–1.99) ≥ 3 0.88 (0.56–1.38) 2.59 (0.97–6.92) 1.63 (0.27–9.88) 1.50 (1.07–2.09) Elevated triglycerides < 0.001 0.155 0 0.58 (0.37–0.91) 1.44 (0.85–2.44) 0.87 (0.60–1.26) 1.10 (0.34–3.51) 1 1 1 1 1 2 1.33 (0.98–1.81) 0.93 (0.70–1.25) 2.10 (1.15–3.83) 1.10 (0.90–1.34) ≥ 3 1.43 (0.88–2.32) 1.23 (0.81–1.87) 3.84 (0.63–23.45) 1.45 (1.15–1.91) Elevated fasting glucose 0.595 0.991 0 NA 0.64 (0.25–1.61) 0.46 (0.18–1.21) NA 1 1 1 1 1 2 1.23 (0.78–1.93) 1.34 (0.94–1.91) 1.82 (0.61–5.38) 1.08 (0.81–1.43) ≥ 3 0.91 (0.47–1.78) 1.23 (0.76–2.01) NA 0.73 (0.48–1.12) Low HDL cholesterol 0.034 0.359 0 1.29 (0.85–1.94) 1.19 (0.64–2.21) 1.01 (0.70–1.47) 2.69 (0.74–9.82) 1 1 1 1 1 2 1.35 (0.85–2.14) 0.89 (0.57–1.38) 0.88 (0.37–2.09) 1.34 (0.98–1.85) ≥ 3 0.54 (0.22–1.35) 0.60 (0.30–1.19) NA 0.81 (0.49–1.35) High blood pressure 0.078 0.523 0 0.48 (0.33–0.71) 0.81 (0.48–1.37) 0.69 (0.48–0.98) 1.13 (0.40–3.16) 1 1 1 1 1 2 1.22 (0.92–1.60) 1.21 (0.88–1.68) 1.33 (0.71–2.47) 1.66 (1.37–2.02) ≥ 3 0.96 (0.60–1.53) 1.73 (1.01–3.00) 5.88 (0.96–36.06) 2.54 (1.88–3.44) Metabolic syndrome < 0.001 0.497 0 0.35 (0.16–0.79) 0.89 (0.51–1.55) 0.65 (0.39–1.08) 1.01 (0.28–3.65) 1 1 1 1 1 2 1.28 (0.89–1.83) 1.17 (0.88–1.57) 1.93 (0.92–4.05) 1.45 (1.19–1.78) ≥ 3 0.90 (0.52–1.54) 1.53 (1.01–2.31) 6.48 (1.06–39.73) 1.90 (1.44–2.51) Note. *Adjusted for age, postmenopause, marital status, current smoking, alcohol use, oral contraceptives, physical activity, education level and income.
#Adjusted for postmenopause, marital status, current smoking, alcohol use, oral contraceptives, physical activity, education level and income. NA: not available.Table 2. Subgroup analyses for the association between parity and five components and metabolic syndrome according to BMI and age
After comparison of all the associations depicted between Figure 3 and Table 2, it appeared that BMI subgroups had no effects on the associations between parity and low HDL cholesterol levels, which showed no significant differences. BMI subgroups partially modified the associations between parity and other four components and MetS. Regarding MetS (Table 2), there were no more associations among women with parity of zero and BMI > 25 kg/m2 and among those with parity of two or with parity of three or more and BMI ≤ 25 kg/m2.
Similar to the above-described results, age subgroups had no effects on the associations between parity and low HDL cholesterol levels, whereas they partially modified the associations between parity and other four components and MetS. Regarding MetS (Table 2), the associations remained significant only among women with parity of three or more and among those with parity of two and age > 45 years.
Effect of Body Mass Index on the Associations between Parity and Metabolic Syndrome and its Components among Northern Chinese Women
doi: 10.3967/bes2020.002
- Received Date: 2019-05-10
- Accepted Date: 2019-09-18
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Key words:
- Parity /
- Metabolic syndrome /
- BMI /
- Risk factor /
- Association
Abstract:
Citation: | YAO Yan, LIU Hua Min, WANG Xian Wei, FENG Xia, GAO Li Jian, LI Dong, ZHOU Yong. Effect of Body Mass Index on the Associations between Parity and Metabolic Syndrome and its Components among Northern Chinese Women[J]. Biomedical and Environmental Sciences, 2020, 33(1): 11-18. doi: 10.3967/bes2020.002 |