Outcomes From Treatment of Infertility With Natural Procreative Technology in an Irish General Practice

Joseph B. Stanford, MD, MSPH; Tracey A. Parnell, MD; Phil C. Boyle, MB


J Am Board Fam Med. 2008;21(5):375-384. 

In This Article


A total of 1,239 couples obtained an initial consult for NPT during the study period. Of these, 167 couples were excluded because they had tried for less than a year to conceive or because they did not continue evaluation beyond the initial consultation. The final study cohort consisted of 1,072 couples that began treatment between February 1998 and January 2002 (inclusive), with subsequent outcomes followed through February 1, 2008. The women were, on average, 35.8 years old (range, 25 to 48 years), and nearly all were white. One third (33%) had previously attempted ART treatment. The mean length of time that couples had attempted to conceive before NPT treatment was 5.6 years (range, 1 to 20 years). Approximately one fourth (24%) of couples had a previous live birth. As shown in Table 1 , the 364 couples who ultimately conceived with NPT treatment were slightly younger (mean age, 34.8 years); had not been attempting conception as long (mean duration, 4.8 years); were likely to have had a previous birth (30%); and less likely to have attempted ART treatment (21%).

In addition to teaching women to track their fertility biomarkers with the Creighton Model instruction, the most common diagnoses given to couples before and after NPT evaluation are shown in Table 2 . Through NPT evaluation, more than half of the couples had suboptimal serum levels of progesterone and estradiol during the luteal phase. Approximately one fourth had limited cervical mucus and 10% had polycystic ovarian syndrome.

The most common treatments given to women included clomiphene (75.3%), support of luteal hormonal production with human chorionic gonadotropin (67%) or progesterone (18%), and medications to enhance cervical mucus production (71%). Fifty-four women (5%) conceived without medical intervention, using only Creighton Model fertility charting and optimally timed intercourse.

There were 354 clinically recognized conceptions within 24 months after starting NPT treatment, with cumulative crude proportions of live births of 19.1 per 100 couples up to 12 months, and 25.5 up to 24 months, as shown in Table 3 . Adjusting for withdrawals from treatment and continuing treatment at the end of study follow-up, the cumulative proportion of first live births was 27.1 up to 12 months, and 52.8 at 24 months. The proportions with any conception (regardless of its outcome) were higher: 25.9 crude and 35.5 adjusted at 12 months, and 33.0 crude and 64.8 adjusted at 24 months. Of conceptions within 2 years leading to a live birth, 75% (205 of 273) occurred within 12 months and 93% (255 of 273) occurred within 18 months.

Several couple characteristics were associated with the probability of live birth, as shown in Table 4 . The cumulative proportion of live births declined with increasing age of the woman. For women under 30, the crude proportion of live birth after 24 months was 33.7. For women over 40 the crude proportion was 13.9. The cumulative crude proportion of live birth also declined with increasing previous attempts to conceive (36.6 for previous time of 1 to 3 years; 11.9 for previous time more than 9 years), and with the number of previous ART attempts (30.8 for none, and 10.3 for 3 or more). Women with a previous birth had a higher cumulative crude proportion of live birth (35.8) than those without (23.1). The adjusted proportions confirm the same trends but should not be considered reliable as precise estimates because most of the subgroup life table analyses involve small numbers of women continuing treatment until 24 months (ie, fewer than 25 women).

Among all live births observed, there were 13 twin births (4.6%) and no higher order births. At least 88% of all births were to term and did not have low birth weight ( Table 5 ). None of the patients in this cohort experienced ovarian hyperstimulation syndrome. The proportion of couples withdrawing from treatment was 44.6 per 100 couples by 12 months, and 62.7 by 24 months ( Table 1 ). Among couples who had a live birth, 51 couples had additional NPT treatment, resulting in 47 additional live births within the study period. However, the results reported here are either for the first conceptions or the first live births only.


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