Disclosures: The authors report no relevant financial disclosures.
August 11, 2021
2 min read

Age at first pregnancy may mediate early menarche, metabolic syndrome link

Disclosures: The authors report no relevant financial disclosures.
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Age at first pregnancy may indirectly affect the association between early menarche and an increased risk for metabolic syndrome in middle-aged and older women, according to a study published in Menopause.

“To the best of knowledge, this was the first study to investigate the mediating role of parity and maternal age at first pregnancy in the association between early menarche and metabolic syndrome in a population of low-income middle-aged and older women,” Ingrid Guerra Azevedo, PhD, of the Permanent Academic of Kinesiology in the department of therapeutic processes at the Universidad Catolica de Temuco in Chile, and colleagues wrote. “Although the association between early menarche and metabolic syndrome has been the subject of previous studies, most of these have been conducted in developed countries. Factors that explain these associations may be very different for low-income populations.”

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Researchers conducted a cross-sectional analysis of data collected from 2014 to 2016 from 428 women aged 40 to 80 years living in two municipalities in Brazil. Blood tests were conducted, and HDL cholesterol and triglyceride levels were collected for each participant. Women were considered to have metabolic syndrome if they met three of the following criteria: a fasting blood glucose level of 110 mg/dL or higher, a diabetes diagnosis or prescription for diabetes medication, HDL cholesterol of less than 50 mg/dL, a triglyceride level of 150 mg/dL or higher, the presence of systemic hypertension or hypertension diagnosis, and a waist circumference of more than 88 cm. Age at menarche, age at first pregnancy, number of births, socioeconomic variables and lifestyle variables were self-reported.

Of the study cohort, 10% reported having early menarche at age 11 years or younger. A higher proportion of women who had early menarche also reported a low family income compared with those who had menarche at older than 12 years (88.4% vs. 74.4%). A higher percentage of women with early menarche also had their first pregnancy at younger than 18 years compared with those with later menarche (34.9% vs. 17.9%).

Metabolic syndrome was observed in 50.5% of the study cohort, with 13% of those with metabolic syndrome reporting early menarche vs. 7.1% of those without metabolic syndrome. After adjusting for confounders, women with early menarche had a higher likelihood for metabolic syndrome compared with those with later menarche (OR = 2.26; 95% CI, 1.15-4.47).

In mediation analysis, early menarche had a direct effect on metabolic syndrome (beta = 0.808; 95% CI, 0.107-1.508). After adjusting for current age, education, family income, physical activity and smoking, age at first pregnancy had a significant indirect effect on the likelihood for metabolic syndrome (beta = 0.065; 95% CI, 0.004-0.221). For two participants with the same characteristics except for age at menarche, the average change in metabolic syndrome odds is equal to 0.879 standard deviations, of which an average of 0.065 standard deviations is attributable to the indirect effect of early menarche on maternal age at first pregnancy.

“Our results reinforce the use of intervention to prevent early pregnancies as a health promotion strategy,” the researchers wrote. “These interventions could include facilitating contraception and sex education for younger women, particularly those with early menarche.”