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Natural Procreative Technology – NaPro

Dr. Phil Boyle MICGP, MRCGP, MCRN 11986 and Dr. Philip O'Dwyer MRCOG, MCRN 07919

Natural Procreative Technology (NaProTechnology or NaPro) 1, 2, 3, 4 treats infertility or
recurrent miscarriage using a range of medical and surgical interventions to facilitate
conception through a normal act of intercourse without recourse to any artificial intervention such as intra uterine insemination (IUI) or in vitro fertilisation (IVF). Data published in the Journal of the American Board of Family Medicine in 2008 demonstrated a high success rate with a difficult group of patients. Many were older couples with long standing infertility and previously failed IVF.

Female 37 (G1P0), Male 39, 7 years trying to conceive, polycystic ovaries, and recurrent implantation failure with 3 failed IVF cycles and 1 frozen transfer. This couple presented to our clinic for fertility treatment in April 2009. They had been trying to conceive since January 2002 and previously had 1 unplanned conception and miscarriage at 11 weeks gestation in Oct 1999. The cycle length varied from 32 to 35 days each month. Investigations had included two laparoscopies, hysteroscopy, blood tests on day 3 and progesterone levels on day 21. These investigations showed mild Polycystic Ovaries. All other investigations were reported as normal, including normal semen analysis.

They had 12 cycles of clomiphene – up to 150mg, monitored with ultrasound. They had 3 stimulated cycles of IVF, producing 12 to 14 follicles and transferring 2 to 3 embryos on each occasion without success between February 2006 and March 2009. They had an additional unsuccessful frozen embryo transfer of 2 embryos in June 2006. Additional investigations in the IVF clinic included a full thrombophillia screen and a peripheral blood test for natural killer cells which were normal. The female was noted to have low oestradiol levels with stimulation but no other abnormality was detected.

The NaPro approach incorporates much of what is already used in infertility clinics, the key factor that differentiates NaPro is the way it plans evaluation and treatment to optimize normal reproductive function, based on information obtained from the Creighton Model FertilityCare Charting system (CrMS).
The Creighton Model FertilityCare System (CrMS) 5, 6, 7


Fig. 1. CrMS – Normal Charting Patterns

The CrMS uses the Vaginal Discharge Recording System (VDRS) to objectively document allvaginal discharge in a standardised fashion. With the VDRS a precise code represents a summary of all the discharge for each day. Research has shown that the pattern of discharge gives valuable information regarding cyclical fertility and infertility. A use effectiveness study from over 17,000 cycles showed the CrMS to be as effective as hormonal contraception for family planning4. Clinical experience demonstrates that if the CrMS charting pattern differs from recognised norms there will be a higher incidence of both infertility and miscarriage. (Fig. 2)
                         Fig. 2. CrMS – Abnormal Charting Patterns

Goals of Treatment

Couples who seek NaPro fertility treatment must first learn how to record the CrMS with the help of one of the Creighton Model teacher practitioners, who undergo a 13 month training programme and exam to qualify as competent instructors of the system. Doctors who have trained in NaPro apply a range of medical and surgical treatments to restore a normal pattern to the CrMS. The CrMS serves as a diagnostic tool and an ongoing biological monitor to assess the impact of various interventions.

There are 3 distinct phases to the treatment process.

     Phase 1 (Evaluation) – 2 to 3 months duration
     Phase 2 (Correction) –   2 to 3 months duration
     Phase 3 (Maintenance) – 1 to 15 months duration

Phase 1 - Evaluation

The doctor uses the CrMS to time investigations such as ultrasound follicle tracking, blood tests for progesterone and oestradiol in the mid-luteal phase of the menstrual cycle as well as routine blood tests on day 3 of the menstrual cycle. If considered necessary the woman is referred for laparoscopy and hysteroscopy and the man is advised to have a semen analysis using the Male Factor Pak 8,9, enabling collection of the sample during regular intercourse. Generally it takes 2 to 3 cycles to conduct the charting, timed blood tests and ultrasound in order to establish a list of diagnoses that are contributing to the fertility problem. The more common diagnoses are listed below





Low Progesterone

Immature follicle


Limited (hostile)


Low Oestradiol

Partial rupture

Pelvic Adhesions

Adrenal Fatigue

Poor Follicular



Unruptured follicle

Blocked Fallopian




Corpus Luteum


Delayed Rupture




Polycystic Ovaries



Food intolerance

Reduced ovarian


Absent Cumulus







Uterine Septum

Immune dysfunction

*Clinical diagnosis based on patient's symptoms and/or charting pattern.

Clinically the female had symptoms consistent with endorphin deficiency and was treated with naltrexone; Vitamin D3 and Omega 3 were also started. On review after 3 months the CrMS chart immediately demonstrated a late ovulation event with a very short luteal phase consistent with corpus luteum insufficiency. The luteal phase ranged from 6 to 7 days in length. Our working diagnosis was poor follicular function and corpus luteum insufficiency.


Phase 2 - Correction

NaPro uses a new concept for evaluating and treating hormone deficiency. The day 21 blood test to assess progesterone status is an inadequate assessment. Interpretation of the day 21 progesterone level gives an “all or none” result. If progesterone is above 30nmol/l – you are ovulating. If the levels are below 30nmol/l you are not ovulating and ought to have ovulation induction. In NaPro we take a blood test 7 days after the probable day of ovulation, as indicated by the woman's CrMS fertility chart, allowing for a much more precise assessment of the mid-luteal phase. This “Peak +7” blood test measures both progesterone and oestradiol levels. We use a much higher reference range and insist that progesterone should be between 60 - 100nmol/l and oestradiol between 400 - 900 pmol/l. If blood results are below the target range we find that most women do in fact ovulate, but they usually have sub-optimal follicular development. This can be confirmed by ultrasound follicle tracking or serial oestradiol levels assessed pre-ovulation. Treatment includes ovulation induction to improve the ovulatory dysfunction and to restore a normal appearance to the woman’s fertility cycle. The patient may also have corpus luteum insufficiency which requires additional treatment in the luteal phase of the cycle. Treatment also includes general measures to optimise health such as appropriate diet, exercise and stress reduction.

The patient was treated with letrozole and dosing was modified based on ultrasound follicle tracking and monthly Peak+7 blood test results for progesterone and oestradiol. In addition we recommended HCG mid cycle to facilitate follicle rupture and on days 3,5,7,9 after ovulation to treat the luteal phase of the cycle. Finally we added hydrocortisone to treat symptoms consistent with adrenal fatigue10. With treatment we achieved a normal appearing CrMS chart, with proven follicle rupture by ultrasound, and a healthier, happy patient.

Phase 3 – Maintenance

When the cycle is normal in appearance and both the male and female are in good health we enter the final phase which can last from 1 to 15 cycles, depending on how quickly conception occurs. Appropriate maintenance is monitored with the CrMS and Peak+7 blood levels in each cycle. The CrMS is central to the entire process to assist with the investigations, diagnosis and ongoing treatment strategies we employ. In our experience the CrMS cannot be substituted by other charting methods because of the detailed information the VDRS provides that is necessary to evaluate the cycle and to monitor the response to treatment. During phase 3 the woman’s health continues to improve over time. If the couple do not conceive after 12 optimised cycles, treatment is deemed ineffective and discontinued.

Our patient conceived on her 5th cycle of treatment (second effective cycle) in April 2010. Because of ongoing low progesterone levels in pregnancy, we continued hormone support with progesterone until 36 weeks gestation. She had a normal vaginal delivery of a healthy baby boy, 3.130 Kg in January 2011. Mother was 38 years old at delivery.


DISCUSSION: Infertility and miscarriage are not generally caused by a single diagnosis but are usually the expression of several underlying ill health conditions, which if diagnosed and treated correctly, will result in restoration of normal reproductive function.   A multi-factorial treatment strategy for the chronic condition of infertility may be more effective than the widespread acute strategy employed by IVF with likely healthier outcomes. We believe this approach incorporates the best available elements for management of infertility as a chronic multi-factorial reproductive disorder. The incidence of multiple pregnancy, low birth weight and premature delivery is more
favourable following NaPro treatment compared to IVF.

             Birth outcomes of NaProTechnology compared to IVF (Fig. 4)



Twins – 4.5 %

Twins > 20 %

Low birth weight <5%

Low Birth weight 30%

Premature Delivery = normal rate

Premature Delivery increased 2 fold

J Amer Board Family Med, 20083

Obster Gynecol 2004 and NEJM 2002 11,12,13


The CrMS accurately identified corpus luteum insufficiency which was missed by all of her previous investigations. Appropriate timing of treatment was made possible with the CrMS. Finally, using the CrMS we could see the luteal phase return to a normal length and measure progesterone and oestradiol levels to confirm normal function. Follicle stimulation alone cannot treat this condition and it may be the explanation for her repeated implantation failure with IVF.

In couples without clear indications for IVF the main benefit of early IVF may be to shorten time to pregnancy, a benefit that must be weighed against costs and potential adverse outcomes14. NaPro is a viable option for most patients experiencing infertility or recurrent miscarriage. Future studies examining NaPro and IVF outcomes must be cohort studies comparing populations with similar patient characteristics.


1. Hilgers TW. What is NaProTechnology? In: Hilgers TW, ed. The medical and surgical
   practice of NaProTechnology. Omaha (NE): Pope Paul VI Institute Press; 2004: 19–28.
2. Boyle PC. NaPro technology and infertility: a family physician's approach. In: Hilgers TW,
   ed. The medical and surgical practice of NaProTechnology. Omaha (NE): Pope Paul VI
   Institute Press; 2004: 653–66.
3. Stanford JB, Parnell TA, Boyle PC. Outcomes from treatment of infertility with natural
     procreative technology in an Irish general practice. J Am Board Fam Med 2008; 21: 375–
[Abstract/Free       Full     Text]
4. Boyle PB, Stanford JB. NaProTechnology – A multi-factorial approach to the chronic
     problem of Infertility. Health Sciences, Volume 21, Number 3(75) 2011. ISSN 1392-6373
Here (http://www.fertilitycare.net/documents/NPTMultifactorialApproach.pdf)
5. Hilgers TW, Stanford, JB. Joseph B. Creighton Model NaProEducation Technology for
     Avoiding Pregnancy: Use Effectiveness. J Reprod Med 1998;43:495-502
6. Hilgers TW, Daly KD, Hilgers SK, Prebil AM. Creighton Model Fertility Care System: a
   standardized, case management approach to teaching, book 1, 2nd ed. Omaha (NE):
   Pope Paul VI Institute Press; 2002.
7. Hilgers TW. Introduction to the Creighton Model System. In: Hilgers TW, ed. The medical
   and surgical practice of NaProTechnology. Omaha (NE): Pope Paul VI Institute Press;
   2004: 43–56.
8. Zavos, PM, Characteristics of human ejaculates collected via masturbation and a new
     Silastic seminal fluid collection device. Fertil Steril 43:491, 1985.
9. Zavos, PM, Seminal parameters of ejaculates collected from oligospermic and
     normospermic patients via masturbation and at intercourse with the use of a Silastic
     seminal fluid collection device. Fertil Steril 44:517, 1985.

10. McK Jeffries W, Safe Uses of Cortisol, ISBN-10: 0398066213
11. Jackson RA, Perinatal outcomes in singletons following in vitro fertilization: a meta-
       analysis. Obstet Gynecol 2004 Mar;103(3):551-63.
12. Schieve LA, Meikle SF, Ferre C, Peterson HB, JengG, Wilcox LS. Low and very low birth
       weight in infants conceived with use of assisted reproductive technology. N Engl J Med
13. Hansen M, Kurinczuk JJ, Bower C, Webb S. The risk of major birth defects after
         intracytoplasmic sperm injection and in vitro fertilization. N Engl J Med 2002;346:725–
14. Stanford JB, et al. Cumulative pregnancy probabilities among couples with subfertility.
       Fertil Steril 2010

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