Live birth/parity number and the risk of incident hypertension among parous women during over 13 years of follow‐up

Abstract

The effect of live birth/parity number on incident hypertension was investigated among Iranian parous women aged 30-70 years. The study population included 2188 normotensive women who were enrolled in 1999-2001. They were followed for incident hypertension (based on JNC 7 report) by 3-year intervals up to April 2018. Multivariable Cox proportional hazard models, adjusted for a wide set of potential hypertension risk factors, reproductive factors, and pregnancy complications, were applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of the number of parity/live birth(s) for incident hypertension. Additionally, as a sensitivity analysis, agescale Cox regression was also done. During a median follow-up of 13.5 years, 935 incident hypertension have occurred. Compared to those with two live births, the participants who had 3 and ≥4 live births were at higher risk of hypertension development by the HRs of 1.25 [95% CI: 1.02-1.55] and 1.39 [1.12-1.72], respectively, in the fulladjusted model. Moreover, each additional live birth increased the risk of hypertension by a HR of 1.06 [95%CI: 1.02-1.11]. Results of parity number were also similar. Considering age as time scale also did not change the results generally. The authors found a significant interaction between live birth/parity number and age groups; the adverse effect of higher live birth/parity numbers on hypertension development was mainly found among those aged < 50 years. To sum up, compared to the live birth/parity number of two, Iranian women with ≥3 live birth/parity had a higher risk of incident hypertension; the issue was more prominent among younger mothers.

Association of parity with the prevalence of hypertension in Japan: The Tohoku Medical Megabank Community‐based cohort study

“…These findings align with those of the study by Xu and colleagues, 14 which showed that women with a parity of 4 and ≥5 had a higher risk of hypertension than those with a parity of zero or one, and the association diminished after adjusting for BMI and waist circumference. However, our study contradicted the study by Moazzeni and colleagues, 13 which found that women with parity of 3 had a higher risk of hypertension than those with a parity of 2 even after adjusting for BMI. The average age was 43.64 years in Moazzeni's study, and differences in ethnicity, lifestyle, and study design could have led to different results from our results 13 .…”

“…The average age was 43.64 years in Moazzeni's study, and differences in ethnicity, lifestyle, and study design could have led to different results from our results. 13 On the other hand, Jang reported that parity was associated with a decreasing risk of hypertension in postmenopausal women in Korea. 11 Differences in covariates, study design, lifestyle including intake of salt in eating habits, and number of participants might produce different results from those of our study.…”

“…9,10 Despite inconsistent findings, parity-defined as the number of live births-has been associated with hypertension. [11][12][13][14] Pregnancy can significantly affect a woman's cardiovascular health, and hypertensive disorders of pregnancy (HDP) increase the risk of later-life chronic hypertension. 15 A graded association between parity, particularly grand multiparity, and hypertension has been reported, although some studies showed either no or an inverse association.…”

“…Despite inconsistent findings, parity—defined as the number of live births—has been associated with hypertension 11–14 . Pregnancy can significantly affect a woman's cardiovascular health, and hypertensive disorders of pregnancy (HDP) increase the risk of later‐life chronic hypertension 15 .…”

Parity and Metabolic Syndrome Risk: A Systematic Review and Meta-Analysis of 15 Observational Studies With 62,095 Women

“…In addition, the reduction of estrogen exposure will cause the disorder of lipid metabolism, hypertension, hyperglycemia, and other components of MetS (52,53), which lead to the occurrence of MetS. Second, pregnancy can cause a series of physiological function changes, including but not limited to insulin resistance, abnormal lipid metabolism, hypertension, and central obesity (54)(55)(56)(57). Insulin resistance always appears simultaneously with other metabolic-related diseases, which play a crucial role in the development of MetS (15).…”