Menstrual irregularity is an indicator of endocrine disorders and reproductive health status. It is associated with various diseases and medical conditions, including obesity and underweight. We aimed to assess the association between body weight changes and menstrual irregularity in Korean women.
A total of 4,621 women 19 to 54 years of age who participated in the 2010 to 2012 Korea National Health and Nutrition Examination Survey were included in this study. Self-reported questionnaires were used to collect medical information assessing menstrual health status and body weight changes. Odds ratios (ORs) and 95% confidence interval (CI) were calculated to evaluate the association between body weight changes and menstrual irregularity.
Significantly higher ORs (95% CI) were observed in the association between menstrual irregularity and both weight loss (OR, 1.74; 95% CI, 1.22 to 2.48) and weight gain (OR, 1.45; 95% CI, 1.13 to 1.86) after adjusting for age, body mass index, current smoking, heavy alcohol drinking, regular exercise, calorie intake, education, income, metabolic syndrome, age of menarche, parity, and stress perception. Of note, significant associations were only observed in subjects with obesity and abdominal obesity, but not in non-obese or non-abdominally obese subjects. U-shaped patterns were demonstrated in both obese and abdominally obese subjects, indicating that greater changes in body weight are associated with higher odds of menstrual irregularity.
We found a U-shaped pattern of association between body weight changes and menstrual irregularity among obese women in the general Korean population. This result indicates that not only proper weight management but also changes in body weight may influence the regulation of the menstrual cycle.
Menstruation is a regular discharge of blood and mucosal tissue from the uterus and typically follows a 28-day cycle that is determined by the rising and falling of sex-steroid hormones during the follicular and luteal phases. Menstrual disorders are common gynecological problems in reproductive women. It is reported that the prevalence of menstrual irregularity ranges from 10% to 38% in menstruating women [
Previous reports have suggested that menstrual irregularity is associated with various diseases and medical conditions, such as metabolic syndrome [
This study was conducted using data collected from the Korea National Health and Nutrition Examination Survey (2010 to 2012, KNHANES V). KNHANES is a cross-sectional and nationally representative survey that was conducted by the Division of Chronic Disease Surveillance of the Korea Centers for Disease Control and Prevention. KNHANES was designed to assess national health and nutritional status and consists of a health and nutrition survey collected through household interviews and a health examination and blood sampling conducted in specially equipped examination centers. The sampling frame was designed based on the 2005 population and housing census in Korea and used a rolling sampling design that involved complex, stratified, multistage, clustered, and probability sampling. The details of this survey have been published elsewhere [
Of the 25,534 subjects who participated in the 2010 to 2012 survey, subjects with ages under 19 years (
Self-reported questionnaires were used to collect medical history and lifestyle habit information. Current smokers were defined as those who currently smoke and had smoked at least five packs of cigarettes during their lifetime. Heavy drinkers were defined as subjects who drink more than 30 g/day of alcohol. Regular exercise was defined as performing vigorous physical activity for at least 20 minutes three times a week. Total caloric intake was assessed through a 24-hour dietary recall questionnaire administered by a trained dietitian. Results were calculated using the food composition table developed by the Korean National Rural Resources Development Institute.
To evaluate changes in body weight, the following question was asked “Were there any weight changes compared to 1 year before?” The answer was categorized into “no change (including weight gain and loss of less than 3 kg),” “weight loss (3 to 6, 6 to 10, more than 10 kg),” or “weight gain (3 to 6, 6 to 10, more than 10 kg).” Self-perceived weight status was assessed by asking, “What do you think of your body weight status?” Responses were categorized into three answers, including lean (very lean and a little lean), normal, and obese (very obese and a little obese). Subjective health status was classified into three answers: good (good and very good), intermediate, and bad (bad and very bad). To evaluate mental health status, subjects were asked to report their levels of psychological stress, continuous depressive symptoms lasting more than 2 weeks during the past year (yes or no) and suicidal ideation over the previous year (yes or no). The level of psychological stress was answered as no, a little, a lot, or very much and was recategorized dichotomously as yes or no.
Age at menarche was defined as the age at the start of menstruation and asked as an open-ended question “What age did you have your first menstrual period?” Subjects who answered “no” to the question “Do you have regular menstrual periods?” were classified into the menstrual irregularity group.
Anthropometric measurements were obtained by trained staff members with subjects dressed in a light gown. Waist circumference (WC) was measured in standing position at a level midpoint between the lower rib margin and the iliac crest during minimal respiration and body mass index (BMI) was calculated as the subject's weight (kg) divided by the square of the subject's height (m2). Blood pressure (BP) was measured using a mercury sphygmomanometer three times on the right arm with the subject in a seated position after at least 5 minutes of resting. Blood samples were drawn after at least 8 hours of fasting and were analyzed at a central, certified laboratory (NeoDin Medical Institute, Seoul, Korea). Serum levels of glucose were determined by a hexokinase method; total cholesterol, triglyceride, and high density lipoprotein cholesterol (HDL-C) levels were measured enzymatically with an automatic chemistry analyzer (Hitachi 7600, Hitachi Ltd., Tokyo, Japan); and low density lipoprotein cholesterol (LDL-C) level was calculated using the Friedewald formula. Metabolic syndrome was defined as the presence of ≥3 of the following criteria: (1) abdominal obesity (WC ≥80 cm); (2) high BP (BP ≥130/85 mm Hg) or antihypertensive medication use; (3) fasting glucose (≥100 mg/dL) or antidiabetic medication use; (4) hypertriglyceridemia (≥150 mg/dL); and (5) low HDL-C (<50 mg/dL) or medication use. Self reported hypertension and diabetes were also collected on the questionnaire.
Statistical analyses were conducted using SAS version 9.4 (SAS Institute Inc., Cary, NC, USA). The SAS survey procedure was applied to reflect the complex sampling design and sampling weights of the KNHANES and to provide nationally representative prevalence estimates. Baseline characteristics were described using means±standard error, geometric means (95% confidence interval [CI]) or percentage (standard error).
Metabolic and socioeconomic characteristics of study participants according to body weight changes in the previous year are shown in
Next, we compared the characteristics between the regular and irregular menstruation groups (
Multivariable logistic regression analysis was performed to estimate the odds of having menstrual irregularity in the weight loss and weight gain groups using the no change group as a reference (
Next, we assessed whether these findings are similar in both non-obese and obese participants. Interestingly, significant associations were only observed in subjects with obesity and abdominal obesity, but not in non-obese or non-abdominally obese subjects. After adjusting for possible confounding factors, the odds of menstrual irregularity was 233% and 207% higher in the weight loss groups who were obese or abdominally obese, respectively. Similarly, weight gain was associated with 162% and 343% greater odds of menstrual irregularity in obese or abdominally obese subjects, respectively.
To evaluate the specific pattern of association between menstrual irregularity and weight changes, weight change values were classified into five subgroups (6 to 10 kg loss, 3 to 6 kg loss, no change, 3 to 6 kg gain, 6 to 10 kg gain). No significant association was noted in non-obese or non-abdominally obese subjects. In contrast, U-shaped patterns were observed in both obese and abdominally obese subjects, indicating that greater changes in body weight are associated with higher risk of menstrual irregularity (
This cross-sectional study is the first large-scale investigation of the association between body weight changes and menstrual irregularity using nationally representative data. We found that menstrual irregularity was associated with body weight changes over the previous year. Furthermore, this association differed by obesity status. Within the obese and abdominally obese groups, both weight gain and weight loss had significant U-shaped associations with increased odds of menstrual irregularity. However, there was no association between menstrual irregularity and body weight changes in the non-obese or non-abdominally obese group.
Obesity is associated with many comorbidities and obese women frequently suffer from reproductive disorders, including polycystic ovary syndrome, infertility, and menstrual disorders [
There are several known mechanisms for the influence of adipose tissue on ovulation and menstrual cycle: (1) adipose tissue converts androgens to estrogen by aromatization in breast, abdomen, omentum, and fatty marrow of long bones; (2) body weight influences the direction of estrogen metabolism, with very thin women producing a less potent inactivated form of estrogen (2-hydroxylated form) and obese women producing more potent forms of estrogen because of activated estrogenic activity (16-hydroxylated form); (3) obese women have diminished capacity for estrogen binding with SHBG, which inactivates estrogen and results in an elevated percentage of free serum estradiol; and (4) adipose tissue stores steroid hormones in obese women [
Previous studies [
There are several limitations of our study. First, this was a cross-sectional study. Therefore, we cannot estimate the cause-effect relationship between weight changes and menstrual irregularity. Second, because the degree of body weight changes, menstrual irregularity, stress, and depressive symptoms were measured using self-reported questionnaires, information bias may not fully be excluded. In addition, the pattern or severity of menstrual irregularity couldn't be assessed in detail. Third, how the subjects gained or lost body weight was not evaluated, and possible secondary causes leading to weight changes might have remained. Typically, the health implication of intentional and unintentional weight loss can be significantly different. Fourth, we did not have information on the use of oral contraceptives that might affect menstrual irregularity. In spite of these limitations, this study involved a large sample size using nationally representative data in Korean adults. To the best of our knowledge, this is the first study to separately evaluate the relationship between body weight changes and menstrual irregularity in obese and non-obese groups.
In conclusion, we found a U-shaped association between body weight changes and menstrual irregularity in obese group among the general Korean population. This result indicates that not only proper weight management but also changes in body weight may influence in the regulation of menstrual cycle.
No potential conflict of interest relevant to this article was reported.
Characteristic | No change ( |
Weight loss ( |
Weight gain ( |
---|---|---|---|
Age, yr | 36.3±0.2 | 33.3±0.5a | 34.7±0.3a,b |
Weight, kg | 55.4±0.2 | 56.3±0.5 | 61.1±0.3a,b |
Height, cm | 159.5±0.1 | 160.0±0.3 | 159.9±0.2 |
Body mass index, kg/m2 | 21.8±0.1 | 22.0±0.2 | 23.9±0.1a,b |
Waist circumference, cm | 73.1±0.2 | 73.3±0.5 | 78.0±0.3a,b |
Systolic blood pressure, mm Hg | 108.6±0.3 | 108.2±0.6 | 109.5±0.5 |
Diastolic blood pressure, mm Hg | 71.7±0.2 | 71.2±0.5 | 72.8±0.3a,b |
Fasting glucose, mg/dL | 90.5±0.3 | 93.1±1.7 | 91.7±0.6 |
Total cholesterol, mg/dL | 178.5±0.7 | 177.9±1.8 | 182.0±1.3a,b |
Triglyceride, mg/dL | 78.5 (76.6–80.4) | 74.8 (70.4–79.6) | 90.8 (87.2–94.4)a,b |
HDL-C, mg/dL | 57.7±0.3 | 58.3±0.7 | 55.8±0.4a,b |
LDL-C, mg/dL | 102.8±0.6 | 101.9±1.6 | 105.1±1.1 |
Current smoking, % | 5.0 (0.5) | 9.8 (1.9)a | 6.8 (0.9)a |
Heavy alcohol drinking, % | 2.1 (0.3) | 3.5 (1.2) | 5.3 (1.0)a |
Regular exercise, % | 15.5 (0.9) | 20.6 (2.2)a | 17.5 (1.4)b |
Energy intake/day, kcal | 1,796.9±16.8 | 1,726.7±41.4 | 1,707.9±24.6a |
Carbohydrate, % | 65.1±0.3 | 63.4±0.6a | 63.7±0.4a |
Fat, % | 20.1±0.2 | 21.4±0.5a | 21.2±0.3a |
Protein, % | 14.8±0.1 | 15.2±0.3 | 15.1±0.2 |
Education, college or higher, % | 44.1 (1.3) | 35.5 (2.5)a | 43.4 (1.9)b |
Income, lowest quartile, % | 8.2 (0.7) | 11.4 (1.8) | 8.2 (1.1) |
Presence of spouse, % | 82.4 (1.2) | 72.3 (3.3)a | 82.3 (1.8)b |
Age of menarche, yr | 13.9±0.0 | 13.7±0.1a | 13.7±0.1a |
Parity, % | 67.7 (1.3) | 56.9 (3.0)a | 63.8 (1.8)b |
Menstrual irregularity, % | 13.1 (0.8) | 18.8 (2.2)a | 17.9 (1.3)a |
More than once/3 months, % | 11.0 (0.7) | 16.3 (2.0) | 14.9 (1.2) |
Less than once/3 months, % | 2.1 (0.3) | 2.5 (0.9) | 3.0 (0.6) |
Values are expressed as mean±SE, geometric mean (95% confidence interval), or % (SE).
HDL-C, high density lipoprotein cholesterol; LDL-C, low density lipoprotein cholesterol.
a
Characteristic | No ( |
Yes ( |
|
---|---|---|---|
Age, yr | 35.6±0.2 | 35.1±0.5 | 0.345 |
Weight, kg | 56.9±0.2 | 58.1±0.5 | 0.013 |
Height, cm | 159.7±0.1 | 159.3±0.3 | 0.151 |
Body mass index, kg/m2 | 22.3±0.1 | 22.9±0.2 | 0.001 |
Waist circumference, cm | 74.2±0.2 | 75.9±0.5 | <0.001 |
Systolic blood pressure, mm Hg | 108.7±0.3 | 109.3±0.6 | 0.337 |
Diastolic blood pressure, mm Hg | 72.0±0.2 | 71.9±0.5 | 0.826 |
Fasting glucose, mg/dL | 91.0±0.3 | 91.7±1.0 | 0.526 |
Total cholesterol, mg/dL | 178.8±0.7 | 182.7±1.7 | 0.031 |
Triglyceride, mg/dL | 80.4 (78.8–82.1) | 86.2 (81.7–91.0) | 0.018 |
HDL-C, mg/dL | 57.4±0.2 | 56.6±0.6 | 0.204 |
LDL-C, mg/dL | 102.8±0.6 | 106.2±1.4 | 0.025 |
Diabetes mellitus, % | 2.4 (0.3) | 4.2 (1.0) | 0.033 |
Hypertension, % | 6.7 (0.5) | 8.6 (1.1) | 0.084 |
Metabolic syndrome, % | 9.9 (0.6) | 14.0 (1.6) | 0.007 |
Current smoking, % | 5.7 (0.5) | 7.7 (1.3) | 0.105 |
Heavy alcohol drinking, % | 3.1 (0.4) | 3.3 (1.0) | 0.866 |
Regular exercise, % | 16.6 (0.7) | 16.3 (1.7) | 0.876 |
Energy intake/day, kcal | 1,765.6±14.0 | 1,759.1±38.4 | 0.875 |
Carbohydrate, % | 64.6±0.2 | 64.4±0.5 | 0.772 |
Fat, % | 20.5±0.2 | 20.8±0.4 | 0.590 |
Protein, % | 14.9±0.1 | 14.8±0.2 | 0.652 |
Education, college or higher, % | 45.0 (1.1) | 31.9 (2.3) | <0.001 |
Income, lowest quartile, % | 8.5 (0.7) | 9.2 (1.5) | 0.643 |
Presence of spouse, % | 82.2 (1.2) | 75.9 (2.6) | 0.005 |
Age of menarche, yr | 13.8±0.0 | 14.0±0.1 | 0.025 |
Parity, % | 66.7 (1.1) | 58.5 (2.4) | 0.001 |
Weight changes in previous 1 year, % | 0.001 | ||
No change | 63.1 (1.0) | 53.7 (2.4) | |
Weight loss | 10.3 (0.6) | 13.6 (1.7) | |
Weight gain | 26.6 (0.9) | 32.7 (2.3) | |
Self-perceived weight status, % | 0.019 | ||
Lean | 12.1 (0.6) | 11.4 (1.4) | |
Normal | 43.0 (1.0) | 36.8 (2.4) | |
Obese | 44.8 (1.0) | 51.8 (2.3) | |
Subjective health status, % | <0.001 | ||
Good | 36.3 (1.0) | 29.2 (2.1) | |
Intermediate | 50.9 (1.1) | 50.3 (2.3) | |
Bad | 12.8 (0.6) | 20.6 (1.8) | |
Stress perception, % | 31.7 (0.9) | 38.9 (2.3) | 0.002 |
Depressive symptom, % | 12.9 (0.6) | 18.5 (1.7) | 0.001 |
Suicidal ideation, % | 14.4 (0.7) | 20.6 (1.9) | 0.034 |
Values are expressed as mean±SE, geometric mean (95% confidence interval), or % (SE).
HDL-C, high density lipoprotein cholesterol; LDL-C, low density lipoprotein cholesterol.
Variable | Total ( |
Obesity (BMI 25 kg/m2) | Abdominal obesity (WC 80 cm) | ||
---|---|---|---|---|---|
No ( |
Yes ( |
No ( |
Yes ( |
||
Model 1a | |||||
No change | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
Weight loss | 1.48 (1.07–2.04) | 1.31 (0.91–1.88) | 2.39 (1.20–4.78) | 1.13 (0.83–1.54) | 1.82 (1.20–2.74) |
Weight gain | 1.30 (1.03–1.64) | 1.04 (0.77–1.41) | 2.35 (1.49–3.70) | 1.27 (0.87–1.85) | 2.36 (1.26–4.42) |
|
0.012 | 0.343 | 0.001 | 0.399 | 0.003 |
Model 2b | |||||
No change | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
Weight loss | 1.65 (1.17–2.33) | 1.43 (0.96–2.11) | 2.77 (1.34–5.72) | 1.16 (0.84–1.61) | 2.07 (1.35–3.18) |
Weight gain | 1.38 (1.09–1.75) | 1.11 (0.81–1.53) | 2.47 (1.54–3.96) | 1.36 (0.91–2.04) | 2.90 (1.51–5.56) |
|
0.002 | 0.192 | <0.001 | 0.268 | <0.001 |
Model 3c | |||||
No change | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
Weight loss | 1.74 (1.22–2.48) | 1.44 (0.97–2.15) | 3.33 (1.60–6.94) | 1.06 (0.70–1.59) | 3.07 (1.81–5.21) |
Weight gain | 1.45 (1.13–1.86) | 1.16 (0.82–1.62) | 2.62 (1.62–4.24) | 1.65 (1.04–2.62) | 4.43 (1.97–9.98) |
|
0.001 | 0.166 | <0.001 | 0.101 | <0.001 |
BMI, body mass index; WC, waist circumference.
aModel 1: adjusted for age and BMI; bModel 2: adjusted for age, BMI, current smoking, heavy alcohol drinking, regular exercise, calorie intake, education, and income; cModel 3: adjusted as model 2 and metabolic syndrome, age of menarche, parity, and stress perception.