Creighton Model charting and pregnancy probabilities

The Creighton Model FertilityCare System is a standardized way of observing and recording cervical mucus across the menstrual cycle. It is taught one-on-one by trained instructors and uses a defined chart so observations can be compared consistently. Research on Creighton has looked at how users following the protocol experience pregnancy, both in the context of trying to avoid and trying to achieve.

The work is useful because it describes a defined, instructed system, rather than fertility charting in general. It is also a reminder that the chart is a tool for observation, not a medical diagnosis on its own.

What this research looked at#

Researchers analyzed cycles from couples who had been taught the Creighton Model and were using the chart to either avoid or achieve pregnancy. They calculated probabilities of pregnancy for cycles where the rules were followed and for cycles where intercourse occurred during the identified fertile time.

What the study found#

Pregnancy probabilities were low for cycles where couples avoided intercourse during the identified fertile time, and noticeably higher when couples chose to have intercourse on identified fertile days. The pattern is consistent with how mucus-based fertility awareness systems are taught: the chart identifies the window, and what couples do with that information drives the outcome.

What this means in plain English#

Creighton charting gives couples a common language for observation and a clear way to identify potentially fertile days. Used carefully, it can support both avoiding pregnancy and timing intercourse to try to conceive. The system depends on consistent observation and on instruction, and it is not the same thing as a medical evaluation.

What this does not prove#

These analyses do not show that charting itself diagnoses or treats any condition, that Creighton is more effective than other defined mucus-based methods, or that broader clinical approaches built on top of charting, such as NaProTechnology, deliver outcomes equivalent to other medical interventions. Those topics require separate, source-specific evidence.

Important limitations#

• Outcomes describe couples instructed in the standardized protocol, not self-taught users.
• Mucus observation requires daily attention and consistency.
• Charting can flag patterns that may be worth discussing with a clinician, but it is not a diagnosis on its own.
• Different life stages, including postpartum and perimenopause, can change mucus patterns and call for additional support.

Why this matters for NFP education#

Creighton illustrates what a standardized, instructor-taught mucus-only method looks like in practice. For people deciding whether a chart-based system is for them, this kind of research helps explain what it can offer (a defined way to identify the fertile window) and what it does not claim to do on its own (medical diagnosis or treatment).

Related reading#

• Creighton Model overview, /methods/creighton
• Cervical mucus, /glossary/cervical-mucus
• Can I use NFP with irregular cycles, /questions/can-i-use-nfp-with-irregular-cycles
• Do I need a certified instructor, /questions/do-i-need-a-certified-instructor
• The science behind NFP, /science
• Browse all methods, /methods