Effectiveness of the Effectiveness of the CREIGHTON MODEL System to CREIGHTON MODEL System to Avoid and to Achieve PregnancyAvoid and to Achieve Pregnancy

Joseph B. Stanford, MD, MSPH, CNFPMC

Associate Professor

Family and Preventive Medicine

University of Utah School of Medicine

Why study use to avoid and achieve?

• Couples who use CrM throughout their life will use it both ways.

• In any CrM program, users will come for both reasons.

• Interest in NFP to achieve is higher than interest to avoid (in USA).– About 33% interested to avoid; 25% to achieve– Missouri and Utah

• What is the effectiveness of CrM to avoid pregnancy?

• What is the effectiveness of CrM to achieve pregnancy?

• How do you distinguish between use to avoid and use to achieve?

• What are the needs for future research?

• What is the effectiveness of CrM to avoid pregnancy?

• What is the effectiveness of CrM to achieve pregnancy?

• How do you distinguish between use to avoid and use to achieve?

• What are the needs for future research?

Distinguishing between use to avoid and use to conceive

• Unplanned and planned pregnancy

• Achieving-related pregnancy

Pregnancy from genital contact during known fertile time

• (Un)planned pregnancy• Fertility control• Responsibility for

pregnancy belongs to the method.

• Subjective, superficially measured.

• Achieving-related pregnancy

• Fertility cooperation• Responsibility for

pregnancy belongs to the couple.

• Objective, based on knowledge and behavior.

Pregnancy from genital contact during known fertile time

• (Un)planned pregnancy• Sex and fertility are

fantasized to be completely separate phenomena.

• “Unplanned” is usually considered to be a negative outcome.

• Achieving-related pregnancy

• Sex and fertility are naturally and inseparably related.

• Achieving-related pregnancy is almost always considered to be a positive outcome.

Consider 2 family planning methods

• Inserted by doctor.

• Suppresses fertility.

• Has to be removed by doctor.

• Encourages couple to forget about their fertility.

• Low method pregnancy rate.

• Low total pregnancy rate.

• “Planned” Parenthood

• Used by couple.• Cooperates with fertility.• Couple is continually

encouraged to consider the gift and possibility of fertility.

• Low method pregnancy rate.

• Higher total pregnancy rate.

• Responsible Parenthood

Distinguishing between use to avoid and use to achieve (CrM)

• Use to avoid is avoidance of genital contact during known times of fertility.– Avoiding-related pregnancy

• Use to achieve is any genital contact during known times of fertility.– Achieving-related pregnancy

• Couples rarely have any difficulty grasping and accepting this approach.

• What is the effectiveness of CrM to avoid pregnancy?

• What is the effectiveness of CrM to achieve pregnancy?

• How do you distinguish between use to avoid and use to achieve?

• What are the needs for future research?

Avoiding-related pregnancy rates

• During use to avoid, method-consistent– method-related pregnancy rate– if method always used perfectly to avoid pregnancy

• During use to avoid, method-inconsistent– use-related pregnancy rate– as method is used in “real life”

• includes errors by user and/or teacher• Either of these can be calculated with full-

denominator or specific denominator.– Illustrate with method-consistent use

Method (perfect use) pregnancy rates during use to avoid

a

b

Perfect use = a / [1+2] {full denominator; traditional measure}

1

1

2

2

Perfect use = a / [1] {specific denominator; new measure}

2= cycles of “real life” use with errors; b= pregnancy due to error

1= cycles of method-consistent use; a= perfect use pregnancy

Statistical approaches

• Pearl rates– Influenced by length of follow-up (more=lower)

• Net life table (multiple decrement)– Influenced by rate of discontinuation

• Gross life table (single decrement)– Independent of rate of discontinuation– Higher rates than net life table

• Kaplan-Meier (similar to life table)• Cox Proportional Hazards Regression

– Multivariate modeling

Method (perfect) use pregnancy rates during use to avoid

Selected CrM studies, full denominator, 12-month

Location Year Couple-months

NET Pregnancy Rate per 100

GROSS Pregnancy Rate per 100

Wichita 1985 2471 0.6 1.0

Houston 1989 5731 0.2 0.2

USA, 5 sites 1998 14,225 0.5 0.7

Avoiding use pregnancy rates Selected CrM studies, full denominator, 12-month

Location Year Couple-months

NET Pregnancy Rate per 100

GROSS Pregnancy Rate per 100

Wichita 1985 2471 2.1 3.3

Houston 1989, 1999

5731 2.8 3.9

USA, 5 sites 1998 14,225 3.2 4.7

CrM Effectiveness

• Important Factors• Standardized method• Personalized

instruction• Competent, trained

teachers• Motivation• Couple

communication

• Not Important• Regular cycles• Educational status• Socioeconomic status• Religious

denomination

• What is the effectiveness of CrM to avoid pregnancy?

• What is the effectiveness of CrM to achieve pregnancy?

• How do you distinguish between use to avoid and use to achieve?

• What are the needs for future research?

1. The achieving related pregnancy rate is a demographic measure of consciously chosen fertility in the population over all cycles of use (full denominator)

May include many cycles used to avoid2. Normal fertility, pregnancy rate in cycles

used to achieve (specific denominator)Includes only cycles used to achieve

3. Infertility, pregnancy rate (specific denominator)

Essentially includes only cycles used to achieveWith or without Natural Procreative Technology

Effectiveness to achieve pregnancy

Selected studies of CrM to achieveCrM Study Denominator Couples Pregnancy

Rate per 100

Comments

Meta-analysis, 1998

Full- all study cycles/months

1876 21.0 net

28.2 gross

Normal fertility

Many couples in study never tried to achieve pregnancy

Fertility-focused intercourse study

Specific- only cycles to achieve

50 76 in first cycle; 100% at 7 cycles

Normal fertility

Excluded couples not conceiving (retrospective)

Irish Medical NPT Study

Specific- only cycles to achieve

1239 46.3 up to 24 months

Infertility

Mean age 36 years

29% previously failed IVF

Effectiveness in infertility, method issues

• Per cycle success rates are not appropriate for CrM (or any infertility treatment).– Biased measures used extensively for IVF and

related techniques.• Cohort-based measures are appropriate for

CrM, and to compare CrM to other infertility treatments.

• Crude rates will underestimate effectiveness.• Traditional life tables will overestimate

effectiveness (but probably less for CrM than for IVF).

CrM: effectiveness summary• With exact use to avoid pregnancy, yearly pregnancy

rates are less than 1 per 100.

• Accounting for user or teacher error, the yearly avoiding pregnancy rates are 2 to 5 per 100.– Effective teaching required.– CrM can be used in all reproductive situations to avoid.

• Irregular cycles, discontinuing oral contraceptives, breastfeeding

• (Most clearly shown in Creighton Model Texas study, 1999)

CrM: effectiveness summary

• Nearly all pregnancies among CrM users result from intercourse during known fertile days.– The total pregnancy rate in CrM studies ranges

from 17 to 33 at one year (per 100, Net).– The achieving-related pregnancy rate ranges from

14 to 30 at one year (per 100, Net).– Achieving-related pregnancy varies by external

circumstances (ie, unemployment rates)

CrM: effectiveness summary

• CrM is the method of choice for seeking pregnancy in infertility.– Depending on underlying age and diagnoseis,

pregnancy rates without NPT may be around 33%– With Natural Procreative Technology, pregnancy

rates will be 40-80% or even higher, depending on underlying age and diagnosis.

• What is the effectiveness of CrM to avoid pregnancy?

• What is the effectiveness of CrM to achieve pregnancy?

• How do you distinguish between use to avoid and use to achieve?

• What are the needs for future research?

Evaluating CrM Effectiveness

• We need new CrM studies with the “specific denominator” approach for both avoiding and achieving pregnancy.

• We especially need studies in– Breastfeeding women (avoiding)– Premenopause (avoiding)– Normal fertility (prospective, achieving)– Women using yellow stamps (postpeak and prepeak)– Different subtypes of infertility with medical or

medical+surgical NPT• We need thorough, sound studies of the dynamics

of achieving-related use.