| Wilcox A,
Weinberg C, Baird D. Timing of sexual intercourse
in relation to ovulation. Neng J Med 1995; 333:
1517-1521
A sample of healthy women who were planning to
become pregnant were monitored in order to estimate
the day of ovulation. The authors concluded that,
among healthy women trying to conceive, nearly
all pregnancies can be attributed to intercourse
during a six-day period ending on the day of ovulation
and that the timing of sexual intercourse in relation
to ovulation has no influence on the sex of the
baby.
Full text available at
http://content.nejm.org/cgi/content/abstract/333/23/1517
Labbok M, Klaus H, Barker D. Factors
related to ovulation method efficacy in three
programs: Bangladesh, Kenya, and Korea. Contraception
1988; 37: 577-589.
Analyzes sociodemographic and reproductive health
data for acceptors in three programs offering
the Ovulation Method of Natural Family Planning.
Increasing age, education, previous pill use and
previous family planning were found to be significantly
associated with fewer unplanned pregnancies while
religion, attendance as a couple, family planning
intention, size and source of referral did not
appear to have a demonstrated impact on pregnancy
occurrence.
Trussell J, Grummer-Strawn L. Contraception
failure of the ovulation method of periodic abstinence.
Fam Plann Perspect 1990; 22: 65-75.
Data from a World Health Organization clinical
trial of the ovulation method of periodic abstinence
show that although the ovulation method is very
effective when used perfectly, it is unforgiving
of imperfect use. Because perfect compliance to
method rules is difficult for many couples, the
ovulation method cannot be considered an ideal
contraceptive method for the typical couple, and
those likely to risk having intercourse on the
forbidden days should be counseled on the probable
consequences.
World Health Organization. A prospective
multicenter trial of the ovulation method of natural
family planning. V. Psychosexual aspects. Fertil
Steril 1987; 47: 765-772.
During the 13-cycle effectiveness phase of a five-center
study of the ovulation method of natural family
planning, there were substantial differences,
particularly between the two developed and the
three developing countries, in the stated degree
of satisfaction with the frequency of intercourse
and in expressed difficulties associated with
abstinence.
Trussell J. Contraceptive Efficacy. Contraception
Technology. Hatcher R, et al., eds. 1998: 779-801.
6. Kambic R, Lamprecht V. Calendar rhythm
efficacy: a review. Adv. Contracept 1996; 12:
123-128.
A meta-analysis of eight studies of calendar rhythm
published between 1940 and 1989 was conducted
to estimate the unplanned pregnancy rate of calendar
rhythm. The authors concluded that properly done
clinical trials of the calendar rhythm method
are needed to scientifically establish its effectiveness.
Hartzen P. Effectiveness of the temperature
rhythm system of contraception. Fertil steril
1967; 18: 694-706.
Marshall J. A field trial of the basal
body temperature method of regulating births.
Lancet 1968; 316: 8-10
A prospective study of couples using the basal
body temperature method of regulating births demonstrated
that this method is effective and free from side
effects. The effect of the considerable periods
of abstinence required by the couple on their
interpersonal relations requires further analysis.
Trussell J, Grummer-Strawn L. op cit.
World Health Organization: A prospective
multicenter trial of the ovulation method of natural
family planning. II. The effectiveness phase.
Fertile Steril 1981; 36: 591-598.
A five-country prospective study was undertaken
to determine the effectiveness of the ovulation
method of natural family planning. This paper
describes pregnancy rates and probabilities of
discontinuation.
Frank-Herrmann P, Freundl G, et al. Natural
family planning with and without barrier method
use in the fertile phase: efficacy in relation
to sexual behavior. Adv Contracept 1997; 13: 179-189.
A large prospective long-term study of natural
family planning (NFP) users was conducted to analyze
the relation between unintended pregnancy rates
and sexual behavior with special reference to
barrier method use in the fertile phase. The study
found no significant difference between NFP users
and mixed methods users (additional barrier method
use in the fertile phase in some cycles) and also
no significant effect of duration of use in the
first 5 years of exposure.
Guida M, et al. An overview on the effectiveness
of natural family planning. Gynecological Endocrinology
1997; 11: 203-219.
A review of the main studies regarding the effectiveness
of NFP showed a decrease in the Pearl Index and
life table values from the early 1980s to date,
indicating that progress both in the teaching
and in the application of these contraception
methods has been achieved. The main cause of lack
of success seems to be the misapplication of NFP
rules, whereas the errors due to the method itself
are few.
Bitto A, et al. Adverse outcome of planned
and unplanned pregnancies among users of natural
family planning: a prospective study. American
Journal of Public Health 1997; 87: 338 - 43.
This study followed women who became pregnant
(planned and unplanned pregnancies) while using
natural family planning to determine prospectively
whether unplanned pregnancies are associated with
adverse pregnancy outcomes among users of natural
family planning. No increased risk of adverse
pregnancy outcomes was observed among women who
experienced an unplanned pregnancy while using
natural family planning.
Gray R, Simpson J L, et al. Timing of
conception and risk of spontaneous abortion among
pregnancies occurring during the use of natural
family planning. American Journal of Obstetrics
and Gynecology 1995; 172: 1567-1572.
The results of a large, multicenter study suggest
that users of natural family planning are not
at increased risk of spontaneous abortion, even
when conceptions are not optimally timed.
Simpson J L, et al. Pregnancy outcome
in natural family planning users: cohort and case-control
studies evaluating safety. Adv Contracept 1997;
13: 201-214.
Conceptions involving aging gametes are of relevance
to natural family planning (NFP) because women
using NFP to avoid pregnancy abstain from intercourse
during the fertile time of the cycle. To help
verify the safety of pregnancies occurring among
NFP practitioners, a large cohort study involving
six experienced NFP centers has been conducted
since 1986. Several studies have already been
completed, cohort as well as case-control in nature.
Gray R, et al. Sex ratio associated with
timing of insemination and length of the follicular
phase in planned and unplanned pregnancies during
use of natural family planning. Human Reproduction
1998; 13: 1397-1400.
The authors used data from a multinational, prospective
study of pregnancies among natural family planning
(NFP) users to investigate the association between
timing of conception the sex ratio at birth. The
sex ratio did not vary consistently or significantly
with the estimated timing of insemination relative
to the day of ovulation, with the estimated length
of the follicular phase, or with the planned or
unplanned status of the pregnancy. These findings
therefore suggest that manipulating the timing
of insemination during the cycle cannot be used
to affect the sex of offspring.
Full text available at http://humrep.oxfordjournals.org/cgi/reprint/13/5/1397
World Health Organization. Fertility
awareness methods: report on a WHO workshop, August
26-29, 1986, in Jablonna, Poland.
Describes recommendations for promotion, teaching,
provision, and research on fertility awareness
methods.
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