What is a 28 day cycle?
Menstrual cycle
This article focuses on the human menstrual cycle, a "monthly" cycle that can vary around an average of ~28 days per cycle.
Menstrual cycle Combined oral contraceptive pill Folliculogenesis Functional hypothalamic amenorrhea Ovarian cancer Menstruation Ovulation Puberty In vitro fertilisation Human sexuality Progestogen (medication) Hormonal contraception Menopause Human reproductive ecology Luteal phase Gonadotropin surge-attenuating factor Implantation (embryology) Human body Estradiol Luteinizing hormone Vagina Polycystic ovary syndrome Pharmacokinetics of progesterone Progesterone (medication) Feminizing hormone therapy Pregnancy Ovary Pharmacokinetics of estradiol Premenstrual dysphoric disorder Pharmacodynamics of progesterone Estrogen (medication) Amenorrhea Fertility testing Estrogen Follicular phase LGBT reproduction Endometrium Progesterone Menstrual suppression Endometriosis Estrous cycle Birth control Anovulation Congenital adrenal hyperplasia due to 21-hydroxylase deficiency Corpus luteum Endometrial cancer Elagolix Estradiol (medication) Hypothalamic–pituitary–gonadal axis Follicular atresia Breastfeeding Infertility Ectopic pregnancy Implantation (human embryo) Human chorionic gonadotropin Culture and menstruation Follicle-stimulating hormone Anti-Müllerian hormone Breast cancer Hyperandrogenism Acne Adolescence Fertility awareness Miscarriage Ovulation induction Menstrual synchrony Childbirth In vitro maturation Ovarian follicle activation Hormone replacement therapy Physical attractiveness Pharmacology of bicalutamide Testosterone Preimplantation genetic diagnosis Immunocontraception Anabolic steroid Cervix Pharmacodynamics of estradiol Embryo transfer Sexual and reproductive health Dydrogesterone Women's reproductive health in the United States Clomifene Controlled ovarian hyperstimulation Pharmacology of cyproterone acetate Maternal physiological changes in pregnancy Artificial insemination Germ cell Family planning Primary ovarian insufficiency Combined hormonal contraception Breast development Oogenesis Egg donation Human embryonic development Dysmenorrhea Health effects of Bisphenol A Relative energy deficiency in sport Prolactin Fertility Endocrine disruptor Female infertility Hypopituitarism Emergency contraception Xenoestrogen Intrauterine device Premenstrual syndrome Chorionic gonadotropin beta Antiandrogen N-Acylethanolamine Drospirenone Induced ovulation (animals) Health effects of electronic cigarettes Menstruation (mammal) Uterine fibroid Gynecomastia Thyroid Catamenial epilepsy Menstrual disorder Preterm birth Fallopian tube Vulva Delayed puberty Spironolactone Levonorgestrel Chemotherapy Müllerian anomalies Norethisterone Breast Endocrine gland Sexual intercourse Turner syndrome Infertility in polycystic ovary syndrome Endocrine system Side effects of cyproterone acetate Induced stem cells Female reproductive system Twin Lactational amenorrhea Human brain Ovarian follicle Uterus Abnormal uterine bleeding Gonadotropin-releasing hormone List of Supernatural characters Epstein–Barr virus–associated lymphoproliferative diseases Postpartum psychosis List of Supernatural and The Winchesters characters Amphibian Ovarian follicle dominance Murine respirovirus Orgasm Drosophila melanogaster Health effects of tobacco Tamoxifen Bicalutamide Anorexia nervosa Mammal Insect morphology Human nutrition Hypothyroidism Epilepsy Kallmann syndrome Cystic fibrosis Pharmacodynamics of spironolactone Immune system Horse colic Clitoris Woman Desogestrel Postpartum depression Hydroxyprogesterone caproate Cattle Heart Risk factors for breast cancer Anterior pituitary Skeletal muscle Frog Child development Body odour and sexual attraction Meiosis Gonadarche Nutritional neuroscience Dopamine Wound healing Dienogest Chlormadinone acetate Glossary of baseball terms Masculinizing hormone therapy Neuroscience of sleep Development of the human body Stroke Diethylstilbestrol Lupus Sexual swelling Homeostasis Estetrol (medication) Growth differentiation factor-9 Aggression Leptin Calendar-based contraceptive methods Lyme disease Millennials Endocrinology of reproduction Fertility medication Relaxin Sex differences in human physiology Hashimoto's thyroiditis Chernobyl disaster Maternal effect Ovarian hyperstimulation syndrome Theca of follicle Well-being contributing factors Reproductive immunology Epigenetics Human reproduction Comparison of birth control methods Parthenogenesis Carcinogenesis Vaginal discharge Pre-eclampsia Bioidentical hormone replacement therapy Red imported fire ant Hyperprolactinaemia Abortion Malaria Type 1 diabetes Cortisol Vaginal bleeding Adrenal gland Generation Z in the United States Vocal cords BRCA mutation Prenatal development Mammary gland Vitamin A Borderline personality disorder Adenomyosis Evidence of common descent Fish physiology TRPV6 Progestogen-only pill Evolutionary history of plants Theca lutein cyst Hypothalamus Lead poisoning Pattern hair loss Physiology of underwater diving Hepatitis Development communication Physiological effects in space Blastocyst Hormonal intrauterine device Megestrol acetate Common ostrich Gonadotropin Saliva testing Addiction Medical uses of bicalutamide Biology and sexual orientation Human reproductive system Cephalopod Crohn's disease Mitochondrion Sexual dysfunction Sexual arousal Basal body temperature Migraine Sexual dimorphism Tubal ligation Chloroplast Elephant Fish reproduction Hypogonadotropic hypogonadism Cooper's hawk Libido Spermatogenesis Developmental psychology Reproductive system Dementia Joseph Lister Cyproterone acetate Sheehan's syndrome Evolutionary psychology Kisspeptin Fertility preservation Radiation therapy Menarche Horse breeding Male infertility Beginning of pregnancy controversy Hypoestrogenism Ovarian reserve Mifepristone Ulcerative colitis Action potential Bipolar disorder Animal sexual behaviour Temporomandibular joint dysfunction Oophorectomy Lemur Index of oncology articles Fish anatomy Hyperthyroidism Respiratory system Bird Rheumatoid arthritis Traditional Chinese medicine Human Lung Women in Islam Iron-deficiency anemia Hypoxia (medicine) Physiology of decompression Sex differences in psychology Amyotrophic lateral sclerosis Ovarian cyst Flutamide Subarachnoid hemorrhage Fish Sexuality after spinal cord injury Gut microbiota Neuroendocrinology Follicle-stimulating hormone insensitivity Marine life Spawn (biology) Luteolysis History of the nude in art Infant mortality Permian–Triassic extinction event Brain Recent human evolution Major depressive disorder Reproductive suppression Pubarche Vaccine hesitancy Contraceptive implant Human digestive system Opioid Asherman's syndrome Radiation effects from the Fukushima Daiichi nuclear disaster Basal metabolic rate Granulosa cell Ovarian apoplexy Oxytocin Biology Antral follicle Eating disorder Bat Pseudopregnancy Epigenetics of physical exercise Danazol Lactation Myocardial infarction Helicobacter pylori Copper IUD Canine reproduction Development of the endocrine system Multiple sclerosis Ebola Cholestasis Air pollution Pregnancy test Diabetes management South African labour law Light in painting Atrial fibrillation HIV/AIDS Domestic violence Onychophora Breast augmentation Lepidoptera Birth defect Economic history of the United Kingdom Concealed ovulation Premature thelarche Multiple birth Management of prostate cancer Leuprorelin Sexuality in ancient Rome Toxoplasmosis Organ-on-a-chip Cerebral palsy Attachment theory Human mating strategies Neanderthal Selective estrogen receptor modulator Risk factors of schizophrenia Mammalian kidney Ganirelix Hypogonadism Biofeedback Spinal cord injury Pediatric gynaecology Generation Z Malnutrition Caffeine Dominance hierarchy Ecology Dairy farming Mood disorder Cocaine Insulin Human fertilization Down syndrome Ozone Sleep deprivation Blockade of Germany (1939–1945) Nerve guidance conduit Serotonin Obesity Extended cycle combined hormonal contraceptive Plasma cell dyscrasias Assisted reproductive technology Sarcoidosis Uterine contraction History of Australia Estradiol valerate Atherosclerosis Osteoporosis Contraceptive vaginal ring Testicle Final maturation induction Adenomyoma Causes of autism Beluga whale The Dresden Files characters Pituitary apoplexy Cervical mucus plug Stress (biology) Neuroscience of sex differences White-tailed eagle Circadian rhythm Dromedary Sexual selection in humans Deep vein thrombosis Sleep Cervical drug delivery Poor ovarian reserve Human skin color Lipoid congenital adrenal hyperplasia Chronic obstructive pulmonary disease Red-tailed hawk Anovulatory cycle Ixodes holocyclus Etonogestrel Copper in biology DNA damage theory of aging Sepsis Adolescent sexuality Domperidone Extended female sexuality Testosterone (medication) Huntington's disease Genetically modified organism Tuberculosis management Marginal zone B-cell lymphoma Abortion in the United States Age and female fertility Amphetamine Prostate cancer Side effects of bicalutamide Climate change in Washington Complete androgen insensitivity syndrome Fibromyalgia Bone morphogenetic protein 15 Fear Influenza Sjögren syndrome Precocious puberty Autoimmune disease in women Western African Ebola virus epidemic Vitamin D Institutional racism Gonadotropin-releasing hormone antagonist Endometriosis and infertility Treatment of equine lameness Aspirin List of My Hero Academia characters List of Pokémon anime characters Pig Reproductive justice Traumatic brain injury Growth hormone Obstructive sleep apnea James Boyer Brown List of Garo characters Artificial ovary Progestogen Evolutionary models of human drug use Plastic pollution Premenstrual water retention Heart rate Incarceration of women in the United States Decompression theory Cetacea Human evolution Economic history of the United States Odor Heavy menstrual bleeding Estrogen insensitivity syndrome Alzheimer's disease Parental investment Adult development Allergy Human microbiome Schizophrenia Thyroid disease Post-traumatic stress disorder Cell cycle Androgen Tissue engineering Alcohol (drug) Transgenerational epigenetic inheritance Maternal health Irritable bowel syndrome Ketogenic diet Mumps Embryology Beginning of human personhood Short-beaked echidna Obsessive–compulsive disorder Thermoregulation Long-eared owl Caesarean section Attention deficit hyperactivity disorder Morphine Hookworm infection Responses to the COVID-19 pandemic in April 2020 Quantitative genetics Heart failure Cilium Human papillomavirus infection Regeneration (biology) Huanjing bunao Lactobacillus vaccine Cell signaling Pancreas Innate lymphoid cell Reelin Contraceptive patch Crocodilia Perlecan Sport psychology Hypothalamic–pituitary–adrenal axis United Kingdom labour law Stem cell Antidepressant Medicine in the medieval Islamic world Polyestradiol phosphate Complications of pregnancy Snowy owl Human tooth development Autism spectrum Neurokinin B Low back pain Drugs in pregnancy Botany Bone Evolution South African criminal law Alcoholism Hippocampus DNA methylation Alcohol and cancer Placenta Epigenetics of anxiety and stress–related disorders Marine plastic pollution Cathode-ray tube Cannabis cultivation Glycodelin Prenatal testing ALS Decidualization Harmful algal bloom Sperm donation Dairy cattle Cat food Estrone (medication) Bivalvia Western honey bee One-child policy Chimera (genetics) Incarceration in the United States Complete blood count Liver Long-term effects of alcohol Spider Vitamin C HPV-positive oropharyngeal cancer Biofilm Oocyte cryopreservation Tyrannosaurus Metformin Iron Animal psychopathology Coral reef Flower Cataract surgery Cryoconservation of animal genetic resources Dihydrotestosterone Electronic cigarette and e-cigarette liquid marketing Fluoxetine Functional magnetic resonance imaging Lithium-ion battery Benzodiazepine Endocrine therapy resistance in breast cancer Insulin (medication) Tourette syndrome Soil Cushing's syndrome Origin of language Sickle cell disease Adult neurogenesis Lung cancer History of life Sleep and memory Vitamin B12 deficiency Enobosarm Drugs and sexual desire Health in Nepal Bryozoa MicroRNA Natural family planning Aphthous stomatitis Genital leiomyoma Dog health Cat Late onset congenital adrenal hyperplasia Management of HIV/AIDS Eurasian goshawk Adipose tissue Maternal death Prostate Behavioral ecology List of Wild Cards characters Compulsory sterilization Political positions of Hillary Clinton Organ transplantation Evolution of human intelligence Cloning Smooth muscle Challenge hypothesis Bacteria Ovarian culture Chronic fatigue syndrome Gonadotropin-releasing hormone agonist Subprime mortgage crisis Tooth decay Child marriage List of Doctor Who universe creatures and aliens Frog test History of women in the United States Human physiology of underwater diving Content theory Osteogenesis imperfecta The Spirit of the Age Earth COVID-19 vaccination in Bulgaria Gestational trophoblastic disease Bird anatomy Reading List of recurring Orange Is the New Black characters Childbirth in Nepal Racial achievement gap in the United States Tartan Cardiac physiology Salamander Virus Cryptorchidism Ovarian drilling Resumption of meiosis Biology of depression Insect Cervical cancer International Space Station List of Fables characters Race and health in the United States Chromopertubation Circumvallate placenta Brain–computer interface Luftnachrichten Abteilung 350 Industrial Revolution Smallpox Rapid eye movement sleep Embryonic stem cell Value-form Effects of stress on memory Androgen backdoor pathway Freeze brand Pineal gland Parasitism Nicotine Nonsteroidal anti-inflammatory drug Condom Teleost List of characters in the Breaking Bad franchise Androgen insensitivity syndrome Reptile Dengue fever Antibody Ural owl Domestic rabbit European Union law Female body shape Sperm guidance Gendered impact of the COVID-19 pandemic Logology (science) Homosexual behavior in animals Snake Fungus Caenorhabditis elegans Somatic cell nuclear transfer Cactus Ethnomusicology Causes of cancer Characters of Casualty Role of Christianity in civilization Plant hormone African humid period Conception device CRISPR gene editing Reproductive rights Networked advocacy Corpus luteum cyst Dolphin Coral Selective progesterone receptor modulator Lymphangioleiomyomatosis Memory Nervous system Women in science Adaptive immune system Prenatal nutrition Sea COVID-19 pandemic Female genital mutilation Inflammation Plasmodium falciparum BDSM History of abortion Ascidiacea Oxygen toxicity Dementia with Lewy bodies Healthcare in the United States Supercapacitor Silviculture Von Willebrand disease Schistosomiasis Epigenetics of human development Bovine somatotropin Cancer epigenetics Staphylococcus aureus Marriage Adrenal insufficiency List of dangerous snakes Sheep Cerebellum Colorectal cancer Gene therapy Luteinizing hormone/choriogonadotropin receptor Wedge-tailed eagle Endocrinology of parenting Breast cancer management Stem-cell niche Metabolic dysfunction–associated steatotic liver disease Mental disorder List of Dutch discoveries Coeliac disease Moon Cancer treatment Transgender pregnancy Das Kapital, Volume I Seed Genetically modified food controversies Creativity Pathology of multiple sclerosis Tubal reversal Food allergy Hormone Graphene Asthma Sexual conflict Gestational diabetes Pituitary gland Delayed onset of lactation Beetle Trisomy X Endothelin 2 Polio Concussion Intracytoplasmic sperm injection Diving rebreather List of Mad Men characters DNA Anatomy Dingo Waist–hip ratio List of Shameless (British TV series) characters Jellyfish Hummingbird History of medicine Toothache Pituitary adenoma Pregnancy rate Zebrafish Sense Sleep problems in women Prenatal cocaine exposure Spermatozoon Binge drinking Octopus Vitamin B12 HIV/AIDS in Russia List of Assassin's Creed characters Female genital disease Ovarian germ cell tumors Rodent Brain tumor Slavery in ancient Rome Imperial Roman army Annelid Cholesterol Education in Ethiopia Sertraline Ungulate protoparvovirus 1 Thymus RNA interference Facioscapulohumeral muscular dystrophy Male reproductive system Muscle contraction Homologous recombination Presidency of Donald Trump Violence against women History of Earth Woolly mammoth Climate change Autism therapies Dog behavior Hemoglobin Zinc List of recurring The Simpsons characters Tasmanian devil Diatom Mammalian reproduction List of Orange Is the New Black characters Social media Endogenous retrovirus Warfarin Preimplantation factor Pancreatic cancer Chicken Spotted hyena Iran–Iraq War Decidua Cultured meat Eusociality Partial androgen insensitivity syndrome Sun Insomnia Fetal alcohol spectrum disorder Macrophage Empathy High-grade serous carcinoma Human body temperature Flint water crisis Autoimmune disease Catamenial pneumothorax Reprogramming Depressant Small supernumerary marker chromosome Selective serotonin reuptake inhibitor Oocyte abnormalities Monarch butterfly Endometrioma Transgenerational trauma Leptospirosis Meningitis Tide Pollen tube List of Farscape characters Secreted frizzled-related protein 1 Pneumonia Birth control in the United States Glucose Prenatal hormones and sexual orientation Sponge Electronic cigarette Mircea Eliade Network neuroscience Fragile X syndrome Vaginal atresia Alkali metal Actin Starfish Acrosome reaction Social grooming Estrogen receptor alpha Sperm competition Psychological stress and sleep H19 (gene) Dog Soybean Stem-cell therapy Antimicrobial resistance Toxoplasma gondii Transvaginal oocyte retrieval Sigmund Freud Protoceratops Educational inequality History of Germany Culture of the United Kingdom Melanoma Shark Kidney Gender inequality Osteopontin Antibiotic New Deal Fracking in the United States Feminine hygiene Blueberry (comics) Apoptosis Capacitor Multiple myeloma Benzodiazepine dependence LGBT parenting Lesbian Body hair Zero-point energy Water on Mars Miscegenation 44th Medical Brigade Anterior cruciate ligament injury Southern bluefin tuna Raloxifene Native Americans in the United States Literacy Dissociative identity disorder COVID-19 vaccine Bengal famine of 1943 Plant defense against herbivory Effects of climate change on agriculture Healthcare and the LGBT community South African contract law Underwater diving Ergot Thyroid hormones Child abuse Embodied cognition Kidney stone disease Sperm whale Red blood cell N,N-Dimethyltryptamine Maritime history of California Amniocentesis History of the United Kingdom Psychology List of The Great Food Truck Race episodes Rebreather diving List of The Shield characters US FWS Charles H. Gilbert Epigenetics of autoimmune disorders Urban forestry Brown bear Diving safety Glaucoma Rape Pregnancy in fish Gene Medication Great horned owl Intersex German radio intelligence operations during World War II Economy of the United States Baby boomers Evolution of sexual reproduction Schistosoma mansoni BRCA1 Gonadotropin-releasing hormone insensitivity Sex hormone-binding globulin Pelvic inflammatory disease Women's Health Initiative Water Sexual reproduction Ozone depletion Cardiac arrest History of Austria Hormonal therapy (oncology) Gasoline Acromegaly Language development List of Regular Show characters Noise-induced hearing loss Healthcare in Canada Melioidosis Gastroparesis Psychopathy Microchimerism Ketoconazole