Professional guidance
American College of Obstetricians and Gynecologists
ACOG provides patient education about women’s health, menstrual cycles, reproductive health, pregnancy, and symptoms that may need clinical attention.
Trusted sources
Ovulation and fertility resources
Use these official health-information sources to learn more about menstrual cycles, ovulation, pregnancy, and when to seek professional advice.
Public health service
NHS
The UK National Health Service offers accessible information about periods, symptoms, pregnancy, fertility, and situations where medical advice is appropriate.
Plain-language reference
MedlinePlus
MedlinePlus, from the U.S. National Library of Medicine, explains menstruation and related health terms in clear language for patients and families.
How to use sources
Read with context
Official sources can explain general health information, but they cannot diagnose an individual situation. Bring persistent symptoms, unusual bleeding, severe pain, fertility concerns, or pregnancy questions to a qualified healthcare professional.
Related guides
Our blog contains educational articles about cycle timing, ovulation signs, pregnancy-test timing, conception planning, and fertility tracking. For a date estimate, use the ovulation calculator and review how estimates work.
Health disclaimer: These links are provided for education and do not replace medical advice, diagnosis, or treatment.