Sympto-Thermal Methods Even before researchers discovered the important role of cervical fluid in identifying the fertile window, physician scientists had researched the role of the basal body temperature BBT and described its use as a method of natural family planning.
Rudolf Vollman and his wife, Emmi, began their research in the s and concluded that a rise in BBT is an accurate indicator of ovulation. Edward Keefe from the United States and Dr. In , Dr. John Marshall conducted the first prospective field trial of the effectiveness of BBT to avoid pregnancy. Over the last 20 years, Dr. Petra Frank-Hermann has conducted two large, high quality trials demonstrating impressive effectiveness rates for the STM to prevent pregnancy.
According to these studies, the sympto-thermal method is Until then, we invite you to share this information with your physician, including the references below. Learn more about the Billings Ovulation Method. For Spanish, click here. Learn more about the Sympto-Thermal Method. Author Bios : Marguerite R.
She travels and writes extensively to educate healthcare professionals about the effectiveness and benefits of FABMs. Her recent interview on the Fertility Friday podcast provides an excellent overview of intriguing and informative facts about fertility awareness the interview begins 3 minutes and 30 seconds into the podcast.
Duane and participated in a number of research projects. Ogino Japan and H. Chicago: Latz Foundation, , Richard J. Bhargava, C. Bhatia, L. Ramachandran, P. There was no logic any longer to submit the reliable indicator the mucus pattern to the judgement of an unreliable method the temperature record.
Mercedes asked whether the Drs Billings would be willing to come to Guatemala to conduct a Teacher- Training and was assured that they would come, Dr Evelyn Billings saying that all that would be taught was the Ovulation Method and that already good results were being reported in the application of the method in Tonga. It had been observed that the shift from the lower to the higher temperature could occur a few days before the day of ovulation or sometimes not until three or four days afterwards, and similar observations were to be found in the medical literature.
There was also experience of another observation also appearing in the medical literature, that ovulation may occur without any indication of it at all from the temperature chart. One's experience had included a cycle with a normal fertile mucus pattern, hormonal proof that the Peak of the Mucus Symptom was accurately located at the time of ovulation, menstruation had occurred two weeks later, but the temperature chart was flat throughout the cycle.
The count of 3 after the end of the mucus pattern had been determined by clinical observations. These involved the cooperation of a number of couples who had successfully postponed pregnancy for as long as they wished to do so and were now wishing to achieve another pregnancy. They were asked to "move backwards" the acts of intercourse in the post-ovulatory phase of the cycle, beginning with day three.
One pregnancy occurred as a result. The remainder moved to day two and now a few pregnancies resulted. When the other couples moved to day one pregnancies occurred more frequently but most frequently of all when finally the last day of the mucus discharge was used for intercourse.
It was some years later that Professor Brown's laboratory studies demonstrated what had been named the "Peak of the Mucus Symptom" was in fact the day on which ovulation occurred most frequently, and that the day after the Peak also had a substantial level of fertility, but not as great as that on the Peak day.
So far the recommendation to proceed further without the temperature method had been confined to those women who had a clear understanding of the Ovulation Method and a classical mucus pattern. What was needed was a study of a random group of women who would be taught the Ovulation Method and use it alone from the beginning of their use of a natural method. Providentially this opportunity presented itself when there was a visit to Melbourne of a Missionary nun of the Marist Order, Sr M Cosmas Weissmann who had already been working for many years in Tonga.
She had come to Melbourne with the express intention of learning a method which did not involve any temperature taking, being positive that the temperature method was incapable of being used successfully amongst the poor and largely illiterate women in Tonga. She was delighted to be told that such a method now existed and she stayed in Melbourne for a few weeks in order to be quite convinced that she fully understood the method and the manner in which it was being taught. Sr Cosmas went back to Tonga and commenced to instruct the women who were keen to learn a natural method of postponing pregnancy, even some who were not intending to use immediately but at a later date when the family size had increased.
Finally a total of women were instructed and couples opted for the Ovulation Method. The trial begun in July and ended in February A visit to Tonga early in the trial confirmed that Sr Cosmas was keeping meticulous records of each individual retained in the trial, and that good progress was being made.
Most women found the mucus immediately recognisable and were pleased with the simplicity of the method. Additional instruction was given where it was necessary to gain the woman's confidence. Altogether a total of couples used the Ovulation Method for a total of months. There was one case where the couple had a pregnancy despite their statement that they had not engaged in intercourse during the fertile phase.
After the report had been published this couple admitted to Sr Cosmas that they had knowingly conceived during the fertile phase and were now anxious to correct the previous untruth. Towards the end of the Drs Billings made a visit to Guatemala in response to an invitation by Mrs Mercedes Wilson and in her company carried out a teaching program in all the countries of Central America. During this visit Mrs Wilson inquired as to whether there was now complete confidence about teaching the Ovulation Method in isolation from other methods, and she was assured this was the case.
She was given more information about the success being achieved in Tonga, and informed that the Ovulation Method was now being regularly used on its own. They had been introduced to him by a letter provided by a priest who had listened to the teaching carried out in Hong Kong.
Deegan listened to the story of the Ovulation Method and arranged for the Drs Billings to meet a group of doctors and nurses to present information to them on return. This meeting with the more than 40 individuals was very successful and a strong resolution was adopted to support the establishment of an Ovulation Method Teaching Centre in Los Angeles.
Mons Deegan followed up this recommendation by organising an Ovulation Method Institute each year for many years afterwards, which continued until his untimely death in They attracted visitors from all over the Americas and also from Asia and Europe. There was also a stop over in Mexico City on the way back to Los Angeles and the Ovulation Method was introduced to an interested group who went ahead with the setting up of a number of centres to teach the method.
Subsequently teachers from Australia were able to supplement the teaching throughout Canada, the United States, and all though Latin America, with assistance to Mercedes Wilson and her group in Guatemala. In our Humanae Vitae Of Human Life Conference attracted delegates from more than 40 countries around the world, enabling our Australian teachers to form strong friendships with individuals from many of these countries who subsequently spread the Ovulation Method on their return home.
Since then many of our Australian Teachers have undertaken journeys to establish teaching programs overseas and these combined efforts have involved more than countries altogether, in Eastern and Western Europe, the Middle East, all through Africa, the subcontinent of India, in Asia and in various Pacific Island communities.
In China these efforts have produced remarkable success in recent years. A publication by the World Health Organisation containing information supplied by Professor Odeblad was distributed; it contained detail regarding his earliest attempts to begin to classify the different types of mucus that he was recognising by modern physical techniques and also under the microscope.
Not long afterwards Dr Kevin Hume learned that Professor Odeblad was to make a visit to Sydney, Australia, in response to an invitation coming from a group of veterinary scientists. Dr Hume was able to attend Professor Odeblad's presentation and afterwards informed him of the development of the Ovulation Method, providing him with copies of the Ovulation Method teaching materials which he took away for further study.
Professor James Brown has added that the Ovulation Method has a rule to provide for every situation the woman may encounter during the reproductive era of her life. Professor Odeblad had been able to explain that fertility has a changing pattern, because there are different types of mucus in varying proportions from day to day up to the time of the Peak of the symptom.
He was able to explain why the stringiness does not persist up to the Peak of the symptom, because a zymogen pre-enzyme is released in granules from the isthmus of the uterus during the fertile phase, to form with the P2 mucus a mucolytic enzyme which breaks up the strings of mucus before the Peak is reached. He made it clear that the lower viscosity of the L-mucus and P2-mucus cause the release of the thick plug of G-mucus from the cervix to begin.
A little of the fluid mucus passes through the vagina to the vulva revealing that sperm are now able to enter the cervical canal. He also pointed out that when the woman is walking the vagina moves a little from side to side and this helps the more fluid mucus to escape. If the woman is at first busy in household or other duties she may postpone micturition by contracting the pelvic musculature and this can obstruct the release of the fluid mucus for a time; he thus confirmed the rule of the Ovulation Method that when it is intended to avoid pregnancy, the couple should not engage in intercourse before the woman has been upright and moving about for some time after getting out of bed.
During the s a committee of the World Health Organisation attached the Billings name to the method, explaining that every new scientific discovery should be given the name of those who made the discovery.
The marriage of the couple has made a covenant in which they give themselves completely to one another and within this gift is their precious fertility. The natural method preserves this unique gift and every act of intercourse remains open to the transmission of life.
The need to wait without intercourse at times is a part of every marriage, because of the birth of a new child, sickness of the husband or the wife, demands of employment and so on. When the couple accepts this gentle discipline they make a magnificent demonstration of their love, the husband for the wife, the wife for the husband, and both together for the children already born and to be born in the future.
Each observes the goodness of their decision so that it has the effect of ennobling them both as they perceive what they have done for each other. They are happy to be cooperating with what the Creator has designed in Nature, are at peace with their conscience, and the family is growing in an atmosphere of love, happiness, security and peace which is so appropriate to the rearing of children, each of whom has experienced the beatitude of having from birth a father and mother who love them and love each other.
Rate this item 1 2 3 4 5 3 votes. Withdrawal has no known side effects, although interruption of the sexual response can diminish a couple's sexual pleasure.
There has been no effectiveness studies conducted on the withdrawal method. This means that between four and 19 women out of would conceive in 1 year using withdrawal method. There are no effectiveness figures available for couples who combine fertility awareness knowledge with withdrawal method; however, it is likely that couples who only use withdrawal during the fertile time could have an increased failure rate. Effective consultations skills are essential for working with clients requesting any user-dependent method.
Ideally, the couple is counseled together. If the woman is seen alone, every effort should be made to discuss the impact of abstinence on the relationship. FAMs alongside contraceptive pills and barrier methods are user-dependent methods.
They all rely on the day-to-day vigilance and motivation of individuals to avoid pregnancy. For individuals who are ambivalent or forgetful, the potential exists to use the method incorrectly or stop using it altogether. Most individuals will get away with the odd forgotten pill or even burst condom over the duration of a cycle; however, FAMs are extremely unforgiving to those who are less-than-perfect users or who are calculated risk takers, because unprotected intercourse occurs at exactly the time when a woman is most likely to be fertile.
Many health professionals believe fertility awareness methods are inappropriate because a woman's libido is highest around ovulation. This belief is not borne out by all research. Thirteen of these studies reported peaks pre and post-menstrually. The length of abstinence is a key factor when considering the acceptability and effectiveness of FAMs. Although the fertile time is only approximately 8—9 days, the number of days of abstinence required varies from 8 to 17 days, depending on the method used.
Difficulties related to the length of abstinence may be directly related to the indicator used. Single-indicator methods generally involve the longest time of abstinence, typically around 16 days. Combined-indicator methods aim to accurately identify the fertile time and reduce the time of abstinence to an average of 10 days. Personal hormone monitoring has the potential for reducing the required time of abstinence still further. The average length of abstinence required by the different methods.
Yet those who promote NFP are strangely silent about the effect of abstinence on the couple John Marshall Marshall and Rowe 74 analyzed detailed psychological questionnaires to ascertain the impact on the relationship of couples who used the temperature method as a single indicator.
This required an average of 17 days of abstinence each month. The majority of couples both men and women found abstinence difficult. Couples who choose to abstain from vaginal intercourse during the fertile time have different ways of coping with abstinence. For some couples this involves being physically apart; for others, it involves being more imaginative with their lovemaking. Bonnar and Lamprecht 75 collected data on alternatives to vaginal intercourse during the fertile time as part of a pilot effectiveness study of Irish women who used a calculation based on the previous six cycles.
The required length of abstinence averaged 16 days. The researchers found that approximately one third of couples avoided genital contact, whereas approximately half of the couples reported using various forms of noncoital sexual activity or outercourse: oral sex, frottage body rubbing , and mutual masturbation.
Although many couples state that they wish only to use abstinence during the fertile time, studies have shown that occasional barrier use is common. In addition, most women who choose to use FAMs for moral or ethical reasons have concerns related to the use of emergency contraception.
Although emergency contraception usually works by preventing fertilization, it is undeniable that the mechanism may prevent implantation. Concerns have been raised about the risk of birth defects or poor pregnancy outcomes caused by aged ovum or sperm at the time of conception. Unintended pregnancies among couples who use natural methods usually result from having intercourse at the beginning or end of the fertile time.
A prospective study showed no significant differences in rates of spontaneous abortion, low birth weight, or preterm birth among women using FAMs who had unintended pregnancies compared with women who had intended pregnancies. The timing of implantation could be related to early pregnancy loss. In a small study, women had a greater chance of having a miscarriage when conception occurred very late in the fertile time.
The receptivity of the endometrium decreases during the late luteal phase, and the corpus luteum is less responsive to HCG by 11 or 12 days after ovulation. Factors intrinsic to the zygote could also be at work. Unhealthy zygotes may develop more slowly or implantation may be abnormal, resulting in later and weaker production of chorionic gonadotrophin.
To the degree that imperfect embryos develop and are implanted more slowly, a limited window of receptivity may provide a gating mechanism to screen out impaired embryos. Larger studies are required to clarify these findings. There has long been an interest in predetermining the sex of the child at the time of conception. The ancient Greeks believed that male sperm were produced in the right testicle and boys were formed on the right or warmer side of the uterus and girls on the left.
French noblemen were reported to have tied up or even cut off their left testicle in the quest for an heir. Over more recent years, endless theories have been expounded related to diet, intercourse position, and timing of intercourse in relation to ovulation.
Despite the passion that this subject can generate, scientifically it seems "to date there is no reliable scientific evidence to support claims made for choosing the sex of the baby, such as timing of intercourse, intercourse positions or diet. A WHO study of approximately births showed no association between timing of conception and the sex ratio at birth. In view of the clinical nature and limiting factors of these treatments, many couples still maintain an active interest in any possible way to predetermine the sex of their offspring.
Although some studies have shown an excess of male births closer to ovulation, others have shown an excess of female births. One study found a link between a short follicular phase and an excess of male births. However, the current evidence clearly demonstrates that the manipulation of the timing of conception or characteristics of the menstrual cycle cannot be used to preselect the sex of the child. Women who are discontinuing hormonal methods of contraception before starting a FAM to achieve or avoid pregnancy require careful management and counseling.
Many family planning providers are not as confident to manage women at this time because the return of fertility is unpredictable. For some women discontinuing the combined pill, the return of fertility is immediate; for others, the resumption of fertility may take more than 6 months. Temporary delays in conception are not unusual after stopping oral contraception particularly for nulliparous women older than 30 years. A German prospective study 86 compared the cycle characteristics of women cycles with a control group of women cycles who had never used oral contraception.
The mean duration of pill use was 3. This is important information for women who wish to avoid pregnancy after stopping pills, because there is a common myth that fertility is suppressed for a while after stopping pills. There were more frequent cycle disturbances in postpill cycles for up to seven cycles after discontinuing the pill.
The cycle disturbances included longer cycles more than 35 days, cycles with shortened luteal phases, and cycles that showed no temperature increase indicating absence of ovulation. It has long been known that breastfeeding reduces female fertility and overall it is a major factor in reducing population growth.
Breastfeeding suppresses ovulation 87 because prolactin levels are raised when breastfeeding. During pregnancy, the levels of prolactin rise but the high levels of estrogen and progesterone prevent the prolactin from stimulating milk production in the breasts.
Immediately after delivery the prolactin level peaks, estrogen and progesterone levels fall, and the prolactin stimulates the breasts to produce milk. Prolactin acts on the pituitary gland, interfering with the action of FSH and LH, reducing the production of estrogen and suppressing follicular growth, hence suppressing ovulation.
Each act of suckling stimulates the production of prolactin, but the level falls again after 3—4 hours. Provided the baby suckles frequently, the level of prolactin remains high and ovulation is suppressed. The natural contraceptive effect of breast-feeding has been recognized throughout history. In BC, Aristotle observed that while women are suckling children, menstruation does not occur according to nature, nor do they conceive.
This temporary reduction in fertility caused by breastfeeding, also known as lactational amenorrhoea, is widely recognized to lengthen intervals between pregnancies in some parts of the world where women often breastfeed for 2 years or longer.
After an international meeting in Italy in , it was formally recognized that breastfeeding was effective to use as a family planning method when certain conditions were met. This means she must breastfeed at regular intervals day and night, give no other liquids or solids as a substitute for breastfeeding, and have no periods no bleeding after the first 8 weeks postpartum.
Once any of these conditions is not being met, the chances of pregnancy increase, even if a woman continues to fully breastfeed and remains amenorrheic after 6 months 91 , 92 Fig. Lactational amenorrhea method algorithm. Definitions of breastfeeding and the impact on fertility.
A recent WHO multicenter study reported that in the first 6 months after childbirth, the cumulative pregnancy rate ranged from 0. Yet practitioners still lack confidence in reassuring women that breastfeeding can act as an effective contraceptive. Breastfeeding has many health benefits for mother and baby. It provides the baby with complete nutrition, a safe food source, and immunological defense against infectious diseases. It also reduces the mother's risk of ovarian and breast cancer. WHO commissioned a systematic review of the published scientific literature on the optimal duration of exclusive breastfeeding, evaluating more than references.
It now recommends exclusive breastfeeding for 6 months, with the introduction of complementary foods and continued breastfeeding thereafter. It establishes a foundation for improving short and long-term health and in so doing can help to reduce health inequalities.
We want to support women in their decision to breastfeed and help them continue to do so. Recommendations for best breastfeeding practice can be found at UNICEF United Kingdom's baby-friendly initiative, 97 which promotes strategies for breastfeeding and providing accurate information for parents. The infant feeding survey 98 confirmed that the most likely groups to breastfeed are older women having received full time education over 18 years and women from higher socio-economic groups.
Therefore, the opportunity for using breastfeeding as a fertility suppressant currently tends to be restricted to a select group. The return of fertility has been compared between breast and bottle feeders. Menstruation can return as early as 5 weeks after the birth in bottle feeders. Women who are not protected by LAM will therefore need to have access to another appropriate and effective method of contraception.
Changes in lifestyle and the need to study or work outside the home often interfere with women's breastfeeding patterns.
Active listening and allowing sufficient time for open-ended questions can provide the necessary space to help women or couples to explore issues related to the recent birth, breastfeeding, the resumption of sexual activity, plans for future children, and counseling about the choice of method suited to the needs of the woman, the couple, and her young family. The choice of method after childbirth needs to take into account the woman's plans, if any, to have further children.
Guillebaud splits the postnatal ages into during breastfeeding; family spacing after breastfeeding, and after the probable last child. Women who have experienced a delay in conceiving in the past need particularly careful counseling.
Some women who have breastfed for long periods, especially if they are in their late 30s, may experience difficulty in conceiving if they are still breastfeeding even infrequently and despite the resumption of menstruation. In the first 6 months postpartum, the majority of women who are fully breastfeeding will be able to rely on LAM see Figs. An additional family planning method should be started at a time when the LAM guidelines no longer apply.
Women wishing to delay their next conception may be well-suited to a FAM by observing signs of returning fertility such as cervical secretions, temperature, and changes in the cervix optional. A woman should start observing her fertility signs approximately 2 weeks before it is expected that the LAM criteria will no longer apply.
Barrier methods, condoms or diaphragms, may be appropriate for breastfeeding women who are spacing their births. The diaphragm size should be checked postnatally. Women who experience dyspareunia pain during intercourse may find that barrier methods are not comfortable. Any additional lubricants required for vaginal dryness must be water-based if rubber barriers are used.
Any progestin-only method is suitable during breastfeeding. Progestin-only pills POPs , the IUS or an implant, may be suitable for family spacers, but the injection Depo-Provera is appropriate only if a long gap is expected between pregnancies, because of the possible delay in returning fertility. For breastfeeding mothers, the dose of progestin to the baby is believed to be harmless, with the quantity being equivalent to one progestin pill in 2 years and considerably less than the progesterone level in dried cows milk.
An IUD is generally suited to family spacers and can be used during breastfeeding. The Personal hormone monitoring system Persona; Unipath is not recommended for use while breastfeeding. A woman should wait until she has had at least two normal menstruations with cycle length 23—35 days before using the monitor with the beginning of the third period.
Combined oral contraception has long been considered unsuitable for breast-feeding women as the estrogen may affect the quantity and constituents of breast milk. However a recent Cochrane Review found no significant differences in infant growth or weight and found the evidence from existing RCTs to be insufficient to establish an effect.
They recommended that at least one properly conducted RCT of adequate size is urgently needed to address this question. Women spacing their next pregnancy are ideally suited to using a FAM or barrier method after breastfeeding, provided they have adequate instruction. Estrogen-containing methods COCs can be used after breastfeeding when increased effectiveness is required. Careful consideration of sexual history is always required for women considering an IUD, particularly in a new relationship or when there may be issues related to exposure to sexually transmitted infections.
Injectable hormonal contraceptives may be appropriate if a longer gap is required between pregnancies. Breastfeeding women who decide that they have completed their family may want more protection than lactational amenorrhea can offer. They may prefer not to rely on highly user-dependent methods such as a FAM or barrier methods.
After the probable last child, there is less concern about protecting fertility or planning the next child, so a longer-term method IUD, IUS, COC, implant, or injectable may be more appropriate. Sterilization of either partner should not be considered immediately postnatally because decisions are more likely to be regretted at this time.
Requests for sterilization at a young age or at the time of birth require particularly effective counseling. Women who have previously used FAMs value being given information about how the cycle length is likely to vary and their likelihood of getting pregnant at this time.
Some women value charting their symptoms, and special charts have been designed that allow for longer cycles. Women who have never used FAMs before find it more difficult to learn to observe the indicators of fertility. Many women experience unusual bleeding patterns during this time.
It is very import to advise women that any change from their normal menstrual pattern should be reported and not to assume that unusual bleeding patterns are physiological when they may be pathological. Women should also be aware that they cannot use FAMs if they are using hormone replacement therapy. Flynn and associates prospectively observed cycles in 36 women aged 45—53 years. All the women were experienced FAM users.
If couples are satisfied with their method of family planning, then they are more likely to use it consistently. It is well-recognized that there is no ideal method of family planning. Increasing the range of choice will help to meet the needs of more couples. The most effective FAMs combine two or more indicators to identify the fertile time, but the contraceptive effectiveness of the method relies on the couple's ability either to abstain or to use a barrier method consistently during the fertile time.
Research clearly demonstrates that motivated couples can use FAMs successfully, provided they are taught by individuals who have been trained to teach FAMs. Many primary health care or family planning clinics in the United Kingdom now integrate fertility awareness knowledge into comprehensive family planning services. A fertility awareness consultation sheet produced in collaboration with the Family Planning Association UK can help to improve consultations and support health professionals discussing fertility awareness and family planning choice.
Provided they have been appropriately informed about their full range of choices and the relative effectiveness, advantages, and disadvantages of methods, many couples irrespective of educational level can learn to use FAMs effectively. Some couples choosing FAMs have frequently already exhausted the contraceptive menu and feel dissatisfied with other methods offered.
Health professionals need to be alert to the emotional needs of their clients and feel comfortable to address how the client will cope during the fertile time. Couples who find this method suits them report enhanced communication within their sexual relationship.
Research clearly demonstrates that motivated couples can use FAMs effectively. Successful use of FAMs depends on adequate teaching and support from a trained practitioner. Many national centers run accredited multidisciplinary courses for health professionals in addition to offering information and referral services. Natural Fertility NZ Inc. The authors thank Dr. Elizabeth Clubb and Dr. Victoria Jennings for their kindness and support in developing this article.
Excerpta Medica , Pyper C: Reproductive health awareness, an important dimension to be integrated into existing programmes. Adv Contracept , Report on a WHO Workshop.
Poland, WHO London, Darton, Longman and Todd, Keefe E: Cephalad shift of the cervix uteri: Sign of the fertile time in women. Int Rev Nat Fam Plan , London, Boston, Faber and Faber, Marriage Life Information.
Sayre, USA, World Health Organisation. Temporal relationships between indices of the fertile period. Fertility Sterility; 39 5 — Br J Fam Plan 24, , Contraception , Fertil Steril , Fordney-Settlage D: A review of cervical mucus and sperm interactions in humans. Int J Fertil , Ferreira-Poblete A: The probability of conception on different days of the cycle with respect to ovulation: An overview. Adv Contracep , Royston P: Basal body temperature, ovulation and the risk of conception on different days of the menstrual cycle with special reference to the lifetimes of the sperm and egg.
Biometrics , Flynn A, Docker M, Morris R et al: The reliability of women's subjective assessment of the fertile period, relative to urinary gonadotrophins and follicular ultrasonic measurements during the menstrual cycle. Collins WP: The evolution of reference methods to monitor ovulation prediction.
Am J Obstet Gynaecol , Hum Reprod , Population Studies , Rees M: The abnormal menstrual cycle. Obstet Gynaecol , Marshall J: A field trial of the basal body temperature method of regulating births. Lancet ii, Chretien FC, Cohen J: Human cervical mucus during the menstrual cycle and pregnancy in normal and pathological conditions. J Reprod Med , Chretien FC: Involvement of the glycoprotein meshwork of cervical mucus in the mechanism of sperm orientation.
Acta Obstet Gynecol Scand , Depares J, Ryder R, Walker S et al: Ovarian ultrasonography highlights precision of symptoms of ovulation as markers of ovulation. Br Med J , Billings JJ: Cervical mucus: The biological marker of fertility and infertility. International J Fertil , Fehring RJ: Accuracy of the peak day of cervical mucus as a biological marker of fertility.
Fam Plan Perspect ,
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