DOCSLIB.ORG

Trends and Patterns in Menarche in the United States: 1995 Through 2013–2017 by Gladys M

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Trends and Patterns in Menarche in the United States: 1995 Through 2013–2017 by Gladys M National Health Statistics Reports Number 146 September 10, 2020 Trends and Patterns in Menarche in the United States: 1995 through 2013–2017 By Gladys M. Martinez, Ph.D. Abstract older, have older friends, and be more likely to engage in negative behaviors Objective—This report presents national estimates of age at first menstrual period such as missing school, smoking, and for women aged 15–44 in the United States in 2013–2017 based on data from the drinking (8–11). The younger the age at National Survey of Family Growth (NSFG). Estimates for 2013–2017 are compared first menstrual period and first sexual with those from previous NSFG survey periods (1995, 2002, and 2006–2010). intercourse, the longer the interval Methods—Data for all survey periods analyzed are based on in-person interviews young women will potentially spend at with nationally representative samples of women in the household population aged risk of pregnancy. Differences in age at 15–44 in the United States. For the 2013–2017 survey period, interviews were menarche across population subgroups conducted with 10,590 female respondents aged 15–44. In 2015–2017, the age range may help explain differences in timing of the NSFG included women aged 15–49, but only those aged 15–44 were included of first sexual intercourse and timing of in this analysis. The response rate for the 2013–2017 NSFG was 67.4% for women. first births. The relationship between age Measures of menarche in this report include average age at first menstrual period, at menarche and the timing of first sexual probability of first menstrual period at each age, and the relationship between age at intercourse in the United States has menarche and age at first sexual intercourse. not been widely studied in the past few Results—The median age at menarche decreased from 1995 (12.1) to 2013–2017 decades. Updated trend data help explain (11.9). The cumulative probability of menarche at young ages was higher in more recent patterns of age at menarche 2013–2017 compared with 1995. Differences in age at menarche exist by Hispanic and timing of first sexual intercourse. origin and race, mother’s education, and living arrangement at age 14. A decreasing Studying demographic patterns linear trend in the probability of age at first sexual intercourse by age at menarche was and trends in menarche may also be seen. informative because earlier age at Keywords: age at first menstrual period • first sexual intercourse • coitarche • menarche has been associated with National Survey of Family Growth greater risk of health problems including breast cancer, obesity, diabetes, and liver disease (12–14). In addition, early age Introduction in which females can potentially get at menarche is associated with early age pregnant (1,2). Early menarche has at menopause (15). Reaching menarche This report focuses on age at been associated with earlier age at first earlier than peers has also been associated first menstrual period, also known as sexual intercourse (3–7). One possible with higher risk of depression, eating age at menarche. It is useful to study mechanism in which early menarche disorders, and substance abuse during demographic patterns in menarche may result in earlier age at first sexual adolescence (8,15,16). Some explanations because this biological milestone intercourse is that girls who experience for early onset of menarche include typically marks the start of the period menarche at younger ages may appear genetics and body fat (via production of U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Disease Control and Prevention National Center for Health Statistics NCHS reports can be downloaded from: https://www.cdc.gov/nchs/products/index.htm. Page 2 National Health Statistics Reports Number 146 September 10, 2020 leptin), while others may be related to Measures of menarche 2013–2017 (61.5 million). SAS software, environmental factors that may impact and age at first sexual Version 9.4 (https://www.sas.com), was reproductive hormones, such as growing intercourse used to produce statistics for this report. up in a father-absent home, stepfather Probabilities in this report were presence, and family conflict (8,12,16). This report measures age at calculated using the Kaplan-Meier Since 1982, the National Survey menarche based on a question procedure in the software program of Family Growth (NSFG) has asked administered by interviewers to SUDAAN 11 (https://www.rti.org/ nationally representative samples of respondents asking, “How old were sudaan). The Kaplan-Meier procedure fits women aged 15–44 about their age at you when you had your first menstrual the Kaplan-Meier model, or product-limit menarche. This report presents estimates period?” (MENARCHE). For estimator, to estimate the survival on age at menarche using data from presentation purposes, the data on age at function for a given population (18,19). four of the more recent NSFG survey menarche are shown in five categories: This method takes censored data and the periods (1995, 2002, 2006–2010, and age 10 or under, age 11, age 12, age 13, NSFG’s complex survey design into 2013–2017). This report provides and age 14 or over. Age at first sexual account. The probability of menarche by national estimates on the trends in age intercourse is defined from a recode age represents the expected proportion of at menarche in the United States and (VRY1STAG) based on a question asking women who have had a first period by a differentials in menarche timing by respondents how old they were the first certain age. Probabilities were estimated various characteristics including age, time they had sexual intercourse with a based on retrospective reporting of the mother’s education, and Hispanic origin man. age at first menstrual period and first and race. In addition, this report explores sexual intercourse. In this report, the relationship between age at menarche Selected demographic probabilities are described as and timing of first sexual intercourse. percentages, such as the percentage of variables women who had their first period by age In this report, age at menarche 12. Women whose period had not yet Methods is shown with respect to several key begun were set to missing in this analysis. demographic characteristics including Similar methodology was used to Data source mother’s education, living arrangement calculate the probability of first sexual with parents at age 14, and Hispanic intercourse, stratified by age at menarche. This report uses NSFG data origin and race. Mother’s education is Significant differences between from 1995, 2002, 2006–2010, and included as a proxy for the respondent’s probabilities were tested using the PROC pooled NSFG data from 2013–2017 socioeconomic status when she would SURVIVAL procedure in SUDAAN. (2013–2015 and 2015–2017). The data have had her first menstrual period. Each table in this report includes standard were collected from women in face-to- Living arrangement with parents at age errors as a measure of the precision of face interviews—10,847 in 1995, 7,643 14 is a measure of the family structure each point estimate. in 2002, 12,279 in 2006–2010, and the respondent grew up in during her 10,590 in 2013–2017—representative early teens and has been associated of the U.S. household population aged with timing of menarche. Hispanic Results 15–44. The National Center for Health origin and race are included in this Statistics (NCHS) has been conducting report because previous studies have Trends in mean age at NSFG since 1973 to collect data on found an association between race and fertility, proximate determinants of menarche ethnicity and age at menarche (6,11). The fertility, and reproductive health. NSFG definition of Hispanic origin and race Table 1 shows mean and median is jointly planned and funded by NCHS used in this report considers the reporting age at menarche among women aged and several other U.S. Department of of more than one race, in accordance 15–44 for four time periods from 1995 Health and Human Services programs with the 1997 guidelines from the Office to 2013–2017. There was a decreasing (see Acknowledgments). The response of Management and Budget (18), and linear trend in the median age at rate for women aged 15–44 in the NSFG while not shown separately, data from menarche in the United States from was 78.5% in 1995, 80% in 2002, 78% respondents reporting more than one race 1995 to 2013–2017. The median age at in 2006–2010, and 67.4% in 2013–2017. are included in the total. menarche decreased from 12.1 in 1995 More details on the sample design, to 11.9 in 2013–2017. In 2013–2017, fieldwork procedures, and variance one-half of women reached menarche by estimation for the 2013–2017 NSFG Statistical analysis age 11 years and 10 months. There was were previously published (https://www. All estimates in this report are no significant difference in mean age at cdc.gov/nchs/nsfg/nsfg_2015_2017_puf. weighted to represent women aged 15–44 menarche from 1995 through 2013–2017. htm#design). in the household population of the United States in 1995 (60.2 million), 2002 (61.6 million), and at the midpoint of 2006–2010 (61.7 million) and National Health Statistics Reports Number 146 September 10, 2020 Page 3 Cumulative probability of in the older ages. Non-Hispanic black parents at age 14, 8% had reached menarche by age women were not significantly different menarche by age 10, 24% by age 11, than Hispanic or non-Hispanic white and 52% by age 12. Among women who Table 2 shows the cumulative women in their probability of menarche lived with their mother and stepfather at probability of menarche by age and at each age.
Load more

Recommended publications
  • Puberty in Girls: Discussing Masturbation
    PUBERTY IN GIRLS: DISCUSSING MASTURBATION Discussing masturbation is an anxiety-provoking moment for any parent. It is important to address the topic with your daughter in a manner that is consistent with your family’s belief system and to set rules that are both age appropriate and comfortable for you to follow through with. This includes acknowledging that it is normal for your daughter to have sexual urges and interest. A good way to open the conversation is through books that discuss puberty and sexual topics in a frank and straightforward manner. Find out what your daughter already knows. Make sure she knows the different parts of her body and their functions. Consider using picture books or a body puzzle to make a simple game such as “find the body part” to see if your daughter understands what the body parts are and their functions; give her a healthy reward or praise to show her that she has done well. Read books together about puberty/adolescence, OR if your daughter doesn’t want to read with you, make them available to her by placing them in places where she plays. When it comes to discussing masturbation, you will need to be explicit. Because many individuals on the autism spectrum tend to self-stimulate in various ways, boundaries must be set around masturbation. Teach rules for appropriate time and place, and tell your daughter that sometimes masturbation is not an option. Provide her with private time where she will be undisturbed. Establish an open dialogue with your daughter about sexuality, which includes being safe and socially appropriate.
    [Show full text]
  • Original Article HISTOLOGICAL CHARACTERISTICS of FOLLICULOGENESIS in MURRAH WATER BUFFALOES DURING the EARLY POSTPUBERTAL PERIOD
    Bulgarian Journal of Veterinary Medicine, 2020, 23, No 1, 8088 ISSN 1311-1477; DOI: 10.15547/bjvm.2156 Original article HISTOLOGICAL CHARACTERISTICS OF FOLLICULOGENESIS IN MURRAH WATER BUFFALOES DURING THE EARLY POSTPUBERTAL PERIOD V. MANOV, V. PLANSKI & G. S. POPOV Faculty of Veterinary Medicine, University of Forestry, Sofia, Bulgaria Summary Manov, V., V. Planski & G. S. Popov, 2020. Histological characteristics of folliculogenesis in Murrah water buffaloes during the early postpubertal period. Bulg. J. Vet. Med., 23, No 1, 8088. A characteristic feature of water buffalo heifers is that they approach breeding maturity later than bovine heifers. From a physiological and endocrinological view, this is related to a later puberty, which affects the overall reproductive performance of water buffalo. The aim of this study was to highlight some morphological characteristics of the water buffalo (Bubalus bubalis) ovaries in the early postpubertal period. The results showed active ovaries of the examined specimens. Some of the follicles had no oocyte, but were with normal structure and physiological activity. Histology is a de- finitive method for examination of ovarian activity in water buffaloes. In some of the ovulating folli- cles the oocyte was absent during early puberty. The presence of corpora lutea confirmed the endo- crine maturity of the hypothalamus-pituitary-gonadal endocrine axis in 11–14 months old heifers despite the absence of oocytes. Key words: corpus luteum, estrus, follicle, ovary, ovulation, postpubertal period, water buffalo heifer INTRODUCTION Water buffalo heifers attain breeding ma- variable and is influenced by a wide vari- turity later than bovine heifers which is ety of factors, including climate, geo- attributed to later onset of puberty, affect- graphic area, breed, season of birth, and ing the overall reproductive performance.
    [Show full text]
  • Puberty—Ready Or Not Expect Some Big Changes
    puberty—ready or not expect some big changes Puberty is the time in your life when your Zits! body starts changing from that of a child to that of an Girls & Boys. adult. At times you may feel like your body is totally Another change that out of control! Your arms, legs, hands, and feet happens during puberty is that your skin gets oilier and you may may grow faster than the rest of your body. You may feel a little start to sweat more. This is because your glands are growing too. clumsier than usual. It’s important to wash every day to keep your skin Compared to your friends you may feel too tall, too short, too clean. Most people use a deodorant or antiperspirant to keep odor fat, or too skinny. You may feel self-conscious about and wetness under control. Don’t be surprised, even if you wash these changes, but many of your friends probably do too. your face every day, that you still get pimples. This is called acne, and it’s normal during this time when your hormone levels are Everyone goes through puberty, but not always at high. Almost all teens get acne at one time or another. the same time or exactly in the same way. In general, here’s Whether your case is mild or severe, there are things you can do what you can expect. to keep it under control. For more information on controlling acne, talk with your pediatrician. When? There’s no “right” time for puberty to begin.
    [Show full text]
  • Dental Considerations in Pregnancy and Menopause
    J Clin Exp Dent. 2011;3(2):e135-44. Pregnancy and menopause in dentistry. Journal section: Oral Medicine and Pathology doi:10.4317/jced.3.e135 Publication Types: Review Dental considerations in pregnancy and menopause Begonya Chaveli López, Mª Gracia Sarrión Pérez, Yolanda Jiménez Soriano Valencia University Medical and Dental School. Valencia (Spain) Correspondence: Apdo. de correos 24 46740 - Carcaixent (Valencia ), Spain E-mail: [email protected] Received: 01/07/2010 Accepted: 05/01/2011 Chaveli López B, Sarrión Pérez MG, Jiménez Soriano Y. Dental conside- rations in pregnancy and menopause. J Clin Exp Dent. 2011;3(2):e135-44. http://www.medicinaoral.com/odo/volumenes/v3i2/jcedv3i2p135.pdf Article Number: 50348 http://www.medicinaoral.com/odo/indice.htm © Medicina Oral S. L. C.I.F. B 96689336 - eISSN: 1989-5488 eMail: [email protected] Abstract The present study offers a literature review of the main oral complications observed in women during pregnancy and menopause, and describes the different dental management protocols used during these periods and during lac- tation, according to the scientific literature. To this effect, a PubMed-Medline search was made, using the following key word combinations: “pregnant and dentistry”, “lactation and dentistry”, “postmenopausal and dentistry”, “me- nopausal and dentistry” and “oral bisphosphonates and dentistry”. The search was limited to reviews, metaanalyses and clinical guides in dental journals published over the last 10 years in English and Spanish. A total of 38 publi- cations were evaluated. Pregnancy can be characterized by an increased prevalence of caries and dental erosions, worsening of pre-existing gingivitis, or the appearance of pyogenic granulomas, among other problems.
    [Show full text]
  • Knowledge About Human Reproduction and Experience of Puberty 4
    KNOWLEDGE ABOUT HUMAN REPRODUCTION AND EXPERIENCE OF PUBERTY 4 4.1 KNOWLEDGE AND EXPERIENCE OF PUBERTY Knowledge of the physiology of human reproduction and the means to protect oneself against sexual or reproductive problems and diseases should be available to adolescents. Better knowledge of these subjects among young adults will lead to correct attitudes and responsible reproductive health behavior. 4.1.1 Knowledge of Physical Changes In the 2002-2003 Indonesia Young Adult Reproductive Health Survey (IYARHS), respondents were asked several questions to measure their knowledge about human reproduction and the experience of puberty. They were asked to name any physical changes that a boy or a girl goes through during the transition from childhood to adolescence. The responses were spontaneous, without any prompting from the interviewer. The findings are presented in Table 4.1. It is interesting to note that while the respondents may have experienced some of the physical changes listed in the questionnaire, some may not have recognized them as part of the process of growing up into adulthood; others may not report them to the interviewer. Table 4.1 Knowledge of physical changes at puberty Percentage of unmarried women and men age 15-24 who know of specific physical changes in a boy and a girl at puberty, by age, IYARHS 2002-2003 Women Men Indicators of physical changes 15-19 20-24 Total 15-19 20-24 Total In a boy Develop muscles 26.3 27.7 26.8 33.1 30.4 32.0 Change in voice 52.2 65.6 56.7 35.5 44.6 39.2 Growth of facial hair, pubic hair,
    [Show full text]
  • 6 Ways Your Brain Transforms During Menopause
    6 Ways Your Brain Transforms During Menopause By Aviva Patz Movies and TV shows have gotten a lot of laughs out of menopause, with its dramatic hot flashes and night sweats. But the midlife transition out of our reproductive years—marked by yo-yoing of hormones, mostly estrogen—is a serious quality-of-life issue for many women, and as we're now learning, may leave permanent marks on our health. "There is a critical window hypothesis in that what is done to treat the symptoms and risk factors during perimenopause predicts future health and symptoms," explains Diana Bitner, MD, assistant professor at Michigan State University College of Human Medicine and author of I Want to Age Like That: Healthy Aging Through Midlife and Menopause. "If women act on the mood changes in perimenopause and get healthy and take estrogen, the symptoms are much better immediately and also lifelong." (Going through menopause and your hormones are out of whack? Then check out The Hormone Reset Diet to balance your hormones and lose weight.) For many decades, the mantra has been that the only true menopausal symptoms are hot flashes and vaginal dryness. Certainly they're the easiest signs to spot! But we have estrogen receptors throughout the brain and body, so when estrogen levels change, we experience the repercussions all over—especially when it comes to how we think and feel. Two large studies, including one of the nation's longest longitudinal investigations, have revealed that there's a lot going on in the brain during this transition. "Before it was hard to tease out: How much of this is due to the ovaries aging and how much is due to the whole body aging?" says Pauline Maki, PhD, professor of psychiatry and psychology at the University of Illinois at Chicago and Immediate Past President of the North American Menopause Society (NAMS).
    [Show full text]
  • Puberty in Boys: from Physical Changes to Masturbation
    PUBERTY IN BOYS: FROM PHYSICAL CHANGES TO MASTURBATION Boys grow and develop (both mentally and physically) at different rates and ages. It is important to know when the “right” time is to begin talking with your son about his development. Ideally, you should begin introducing your son to his body, including his genitals, at an early age. Then, when it is time to talk about the sexual function of his body, it may not be as difficult. Use your judgment in determining when your son is ready for a conversation about puberty and sexuality. For many boys, this may be around age 9 to 11. Keep in mind that it may be earlier or later, depending on your child’s development. Whatever the age, it is important to think about where to begin. Find out what your son knows. Does he already know the body parts? Does he know what it means to have an erection? Use visuals such as drawings and pictures, or use a hand held mirror to help find out if he can name his body parts and genitals and tell you the function of each part. When talking with your son about his body, use the proper or real names of each body part, instead of just saying “down there.” Also teach your son the slang terms for male and female body parts; he is likely to hear them at school or elsewhere. Keep it SIMPLE. For example: “This is your penis: this is where the urine/pee comes out when you use the toilet.” “This is your anus: this is where the stool/poop comes out after your food has been digested.” “This is your penis: this is where semen comes out when you ejaculate.” Be POSITIVE and tell him that his body will grow taller, his testicles and penis will grow bigger, and hair will grow under his arms and in his groin area and that it is NORMAL.
    [Show full text]
  • Female Tanner Stages (Sexual Maturity Rating)
    Strength of Recommendations Preventive Care Visits – 6 to 17 years Bold = Good Greig Health Record Update 2016 Italics = Fair Plain Text = consensus or Selected Guidelines and Resources – Page 3 inconclusive evidence The CRAFFT Screening Interview Begin: “I’m going to ask you a few questions that I ask all my patients. Please be honest. I will keep your Screening for Major Depressive Disorder -USPSTF answers confidential.” Age 12 years to 18 years 7 to 11 yrs No Yes Part A During the past 12 months did you: Screen (when systems in place for diagnosis, treatment and Insufficient 1. Drink any alcohol (more than a few sips)? □ □ follow-up) evidence 2. Smoked any marijuana or hashish? □ □ Risk factors- parental depression, co-morbid mental health or chronic medical 3. Used anything else to get high? (“anything else” includes illegal conditions, having experienced a major negative life event drugs, over the counter and prescription drugs and things that you sniff or “huff”) □ □ Tools-Patient Health Questionnaire for Adolescent(PHQ9-A) Tools For clinic use only: Did the patient answer “yes” to any questions in Part A? &Beck Depression Inventory-Primary Care version (BDI-PC) perform less No □ Yes □ well Ask CAR question only, then stop. Ask all 6 CRAFFT questions Treatment-Pharmacotherapy – fluoxetine (a SSRI) is Part B Have you ever ridden in a CAR driven by someone □ □ efficacious but SSRIs have a risk of suicidality – consider only (including yourself) who was ‘‘high’’ or had been using if clinical monitoring is possible. Psychotherapy alone or alcohol or drugs? combined with pharmacotherapy can be efficacious.
    [Show full text]
  • Precocious Puberty Children with Spina BiDa and Hydrocephalus May Start Puberty Earlier Than Their Peers
    SBA National Resource Center: 800-621-3141 Precocious Puberty Children with Spina Bida and hydrocephalus may start puberty earlier than their peers. What is Puberty? If major breast development starts before age 8, it is considered early. (Sometimes girls will have some Puberty refers to normal body changes that lead to breast development, with no other signs of puberty. maturity and the ability to have children. Normal puberty This isolated change may be normal.) begins between ages 8 and 12 in girls and between 9 and 14 in boys. Hormones made in the brain control the timing and sequence of puberty. These hormones What are the stages of normal puberty in boys? stimulate other parts of the body to make sex hormones. The usual sequence in boys is: The sex hormones, especially estrogen in girls and testosterone in boys, cause sexual maturation. • The testicles grow larger. • The penis grows larger. What are the stages of normal puberty in girls? • Pubic hair grows. The physical changes seen in puberty are labeled by “Tanner staging.” Stage 1 is child-like (before puberty) • There is a growth spurt.rt. and stage 5 is full maturity. The usual sequence in girls is: • Other body hair grows.s. • Breasts start to develop. If boys show major developmentelopment • Hips widen and a there is a growth spurt that usually before age 9, it is considereddered lasts about three to four years. early. Early puberty in girls or boys is called • Pubic hair grows (three-to-six months after breasts “Precocious Puberty.” develop). • Other body hair grows.
    [Show full text]
  • Relation of Cardiovascular Risk Factors in Women Approaching Menopause
    University of Massachusetts Medical School eScholarship@UMMS Women’s Health Research Faculty Publications Women's Faculty Committee 2006-02-24 Relation of cardiovascular risk factors in women approaching menopause to menstrual cycle characteristics and reproductive hormones in the follicular and luteal phases Karen A. Matthews Et al. Let us know how access to this document benefits ou.y Follow this and additional works at: https://escholarship.umassmed.edu/wfc_pp Part of the Cardiology Commons, Obstetrics and Gynecology Commons, and the Preventive Medicine Commons Repository Citation Matthews KA, Santoro N, Lasley WL, Chang Y, Crawford SL, Pasternak RC, Sutton-Tyrrell K, Sowers M. (2006). Relation of cardiovascular risk factors in women approaching menopause to menstrual cycle characteristics and reproductive hormones in the follicular and luteal phases. Women’s Health Research Faculty Publications. https://doi.org/10.1210/jc.2005-1057. Retrieved from https://escholarship.umassmed.edu/wfc_pp/43 This material is brought to you by eScholarship@UMMS. It has been accepted for inclusion in Women’s Health Research Faculty Publications by an authorized administrator of eScholarship@UMMS. For more information, please contact [email protected]. Cardiovascular Risk Factors 1 Are the Cardiovascular Risk Factors of Women Approaching Menopause associated with Menstrual Cycle Characteristics and Reproductive Hormones in the Follicular and Luteal Phase?: Study of Women’s Health Across the Nation Daily Hormone Study Karen A. Matthews, PhD. 1 Nanette Santoro, MD 2, Bill Lasley, PhD. 3, Yuefang Chang, PhD. 4, Sybil Crawford, PhD. 5, Richard C. Pasternak, MD 6, Kim Sutton-Tyrrell, DrPH 4, and Mary Fran Sowers, PhD. 7 1 Departments of Psychiatry, Epidemiology and Psychology, University of Pittsburgh, Pittsburgh, PA.
    [Show full text]
  • Variability in the Length of Menstrual Cycles Within and Between Women - a Review of the Evidence Key Points
    Variability in the Length of Menstrual Cycles Within and Between Women - A Review of the Evidence Key Points • Mean cycle length ranges from 27.3 to 30.1 days between ages 20 and 40 years, follicular phase length is 13-15 days, and luteal phase length is less variable and averages 13-14 days1-3 • Menstrual cycle lengths vary most widely just after menarche and just before menopause primarily as cycles are anovulatory 1 • Mean length of follicular phase declines with age3,11 while luteal phase remains constant to menopause8 • The variability in menstrual cycle length is attributable to follicular phase length1,11 Introduction Follicular and luteal phase lengths Menstrual cycles are the re-occurring physiological – variability of menstrual cycle changes that happen in women of reproductive age. Menstrual cycles are counted from the first day of attributable to follicular phase menstrual flow and last until the day before the next onset of menses. It is generally assumed that the menstrual cycle lasts for 28 days, and this assumption Key Points is typically applied when dating pregnancy. However, there is variability between and within women with regard to the length of the menstrual cycle throughout • Follicular phase length averages 1,11,12 life. A woman who experiences variations of less than 8 13-15 days days between her longest and shortest cycle is considered normal. Irregular cycles are generally • Luteal phase length averages defined as having 8 to 20 days variation in length of 13-14 days1-3 cycle, whereas over 21 days variation in total cycle length is considered very irregular.
    [Show full text]
  • The Evolutionary Ecology of Age at Natural Menopause
    1 The Evolutionary Ecology of Age at Natural 2 Menopause: Implications for Public Health 3 4 Abigail Fraser1,3, Cathy Johnman1, Elise Whitley1, Alexandra Alvergne2,3,4 5 6 7 1 Institute of Health and Wellbeing, University of Glasgow, UK 8 2 ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France 9 3 School of Anthropology & Museum Ethnography, University of Oxford, UK 10 4 Harris Manchester College, University of Oxford, UK 11 12 13 14 15 16 17 18 19 Author for correspondence: 20 [email protected] 21 22 23 Word count: 24 Illustrations: 2 boxes; 3 figures; 1 table 25 26 27 Key words: reproductive cessation, life-history, biocultural, somatic ageing, age at 28 menopause, ovarian ageing. 29 1 30 31 Abstract 32 33 Evolutionary perspectives on menopause have focused on explaining why early 34 reproductive cessation in females has emerged and why it is rare throughout the 35 animal kingdom, but less attention has been given to exploring patterns of diversity in 36 age at natural menopause. In this paper, we aim to generate new hypotheses for 37 understanding human patterns of diversity in this trait, defined as age at final menstrual 38 period. To do so, we develop a multi-level, inter-disciplinary framework, combining 39 proximate, physiological understandings of ovarian ageing with ultimate, evolutionary 40 perspectives on ageing. We begin by reviewing known patterns of diversity in age at 41 natural menopause in humans, and highlight issues in how menopause is currently 42 defined and measured. Second, we consider together ultimate explanations of 43 menopause timing and proximate understandings of ovarian ageing.
    [Show full text]