Fertilitat

Fertilitat, or fertility, is the natural capacity to conceive and reproduce. In humans and other animals it describes the ability to bear viable offspring; in demography it relates to population growth and replacement levels. Infertility is the lack of such capacity after a defined period of trying.

Biologically, fertilitat is regulated by hormones and involves gamete formation: oogenesis in females and spermatogenesis in males. Female fertility typically peaks in the 20s and declines with age, whereas male fertility declines more gradually. Health, lifestyle, disease, and environmental factors can affect both sexes.

Measurement includes demographic indicators such as the total fertility rate (TFR), the average number of children per woman, and fecundity or fecundability. Time-to-pregnancy (TTP) measures how long it takes to conceive. Infertility is commonly defined as failing to conceive after 12 months of regular unprotected intercourse.

Causes and factors include age, obesity, smoking, alcohol, chronic diseases (for example polycystic ovary syndrome and endometriosis in women), low sperm count or motility in men, infections, medications, and environmental exposures. Access to healthcare and social factors influence fertility and family planning decisions.

Fertility treatment and preservation include assisted reproductive technologies such as in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), ovulation induction, and artificial insemination. Fertility preservation methods, like egg or sperm freezing, help people maintain reproductive options for medical or personal reasons.