Basal body temperature

Last updated
Basal body temperature
Background
Type Fertility awareness
First use1930s
Failure rates (first year)
Perfect useUnknown% [1]
Typical useUnknown% [1]
Usage
ReversibilityImmediate
User remindersDependent upon strict user adherence to methodology
Clinic reviewNone
Advantages and disadvantages
STI protectionNo
Period advantagesPrediction
Weight gainNo
BenefitsNo side effects, can aid pregnancy achievement

Basal body temperature (BBT or BTP) is the lowest body temperature attained during rest (usually during sleep). It is usually estimated by a temperature measurement immediately after awakening and before any physical activity has been undertaken. This will lead to a somewhat higher value than the true BBT.

Contents

In women, ovulation causes a sustained increase of at least 0.2 °C (0.4 °F) in BBT. Monitoring BBTs is one way of estimating the day of ovulation. The tendency of a woman to have lower temperatures before ovulation, and higher temperatures afterwards, is known as a biphasic temperature pattern. Charting this pattern may be used as a component of fertility awareness. The BBT of men is comparable to the BBT of women in their follicular phase. [2]

Hormonal causes of biphasic patterns

The higher levels of estrogen present during the pre-ovulatory (follicular) phase of the menstrual cycle lower BBTs. The higher levels of progesterone released by the corpus luteum after ovulation raise BBTs. [3] After ovulation, the temperature will be raised by at least 0.2 °C (0.4 °F), for at least 72 hours, compared to the previous six days. [3] The rise in temperatures can most commonly be seen the day after ovulation, but this varies and BBTs can only be used to estimate ovulation within a three-day range.[ medical citation needed ]

If pregnancy does not occur, the disintegration of the corpus luteum causes a drop in BBTs that roughly coincides with the onset of the next menstruation. If pregnancy does occur, the corpus luteum continues to function (and maintain high BBTs) for the first trimester of the pregnancy. After the first trimester, the woman's body temperature drops to her pre-ovulatory normal as the placenta takes over functions previously performed by the corpus luteum.[ medical citation needed ]

Very rarely, the corpus luteum may form a cyst. A corpus luteum cyst will cause BBTs to stay elevated and prevent menstruation from occurring until it resolves, which could take weeks or months.[ medical citation needed ]

As a birth control method

While avoiding pregnancy

Charting of basal body temperatures is used in some methods of fertility awareness, such as the sympto-thermal method, and may be used to determine the onset of post-ovulatory infertility. [4] When BBT alone is used to avoid a pregnancy, it is sometimes called the Temperature Rhythm method. [4]

Basal body temperature alone is most effective at preventing pregnancy if the couple abstains from intercourse from the beginning of menstruation through the third day after the basal body temperature has risen. [5] BBTs only show when ovulation has occurred; they do not predict ovulation. Sperm typically lasts for at least three days and can survive as long as a week, [3] making prediction of ovulation several days in advance necessary for avoiding pregnancy.

Effectiveness

There is limited evidence about the effectiveness of fertility awareness family planning methods, some of which use basal body temperature as one component. [1] About 24% of women who use any type of fertility awareness program become pregnant during the first year, compared to about 85% of sexually active women who are not trying to prevent a pregnancy. [6] [5]

The World Health Organization ranked fertility awareness methods, taken as a whole, as an "effective" method of preventing pregnancies. [5] The WHO placed fertility awareness methods in the third tier of effectiveness, after "most effective" methods such as IUDs and "very effective" methods such as combined oral contraceptive pills. [5] [7]

Trying to conceive

Couples that are trying to conceive can use BBT to determine when the opportunity for a pregnancy during this cycle has passed.

As a diagnostic test

For infertility

Infertility due to lack of ovulation is common. BBT charts can be used to identify when and whether ovulation is taking place. [3]

Regular menstrual cycles are often taken as evidence that a woman is ovulating normally, and irregular cycles is evidence she is not. However, many women with irregular cycles do ovulate normally, and some with regular cycles are actually anovulatory or have a luteal phase defect. Records of basal body temperature can be used to accurately determine if a woman is ovulating, [8] and if the length of the post-ovulatory (luteal) phase of her menstrual cycle is long enough to sustain a pregnancy.[ medical citation needed ]

For pregnancy

Most pregnancy tests are not accurate until two weeks after ovulation. Knowing an estimated date of ovulation can prevent a woman from getting false negative results due to testing too early. Also, 18 consecutive days of elevated temperatures means a woman is almost certainly pregnant.[ medical citation needed ]

For estimating the timing of childbirth

Calculating the expected due date for a pregnancy based upon the self-reported last menstrual period is less accurate than calculating it based upon either BBT or ultrasound. [8]

Related Research Articles

Emergency contraception Birth control measures taken after sexual intercourse

Emergency contraception (EC) is a birth control measure, used after sexual intercourse to prevent pregnancy.

Fertility awareness

Fertility awareness (FA) refers to a set of practices used to determine the fertile and infertile phases of a woman's menstrual cycle. Fertility awareness methods may be used to avoid pregnancy, to achieve pregnancy, or as a way to monitor gynecological health.

Combined oral contraceptive pill Birth control method which is taken orally

The combined oral contraceptive pill (COCP), often referred to as the birth control pill or colloquially as "the pill", is a type of birth control that is designed to be taken orally by women. It includes a combination of an estrogen and a progestogen. When taken correctly, it alters the menstrual cycle to eliminate ovulation and prevent pregnancy.

Calendar-based methods are various methods of estimating a woman's likelihood of fertility, based on a record of the length of previous menstrual cycles. Various methods are known as the Knaus–Ogino method and the rhythm method. The standard days method is also considered a calendar-based method, because when using it, a woman tracks the days of her menstrual cycle without observing her physical fertility signs. The standard days method is based on a fixed formula taking into consideration the timing of ovulation, the functional life of the sperm and the ovum, and the resulting likelihood of pregnancy on particular days of the menstrual cycle. These methods may be used to achieve pregnancy by timing unprotected intercourse for days identified as fertile, or to avoid pregnancy by avoiding unprotected intercourse during fertile days.

Menstruation Regular discharge of blood and tissue through the vagina

Menstruation is the regular discharge of blood and mucosal tissue from the inner lining of the uterus through the vagina. The menstrual cycle is characterized by the rise and fall of hormones. Menstruation is triggered by falling progesterone levels and is a sign that pregnancy has not occurred.

Menstrual cycle Natural changes in the human female reproductive system

The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that make pregnancy possible. The ovarian cycle controls the production and release of eggs and the cyclic release of estrogen and progesterone. The uterine cycle governs the preparation and maintenance of the lining of the uterus (womb) to receive a fertilized egg. These cycles are concurrent and coordinated, normally last between 21 and 35 days in adult women, with a median length of 28 days, and continue for about 30–45 years.

Ovulation Release of egg cells from the ovaries

Ovulation is the release of eggs from the ovaries. In women, this event occurs when the ovarian follicles rupture and release the secondary oocyte ovarian cells. After ovulation, during the luteal phase, the egg will be available to be fertilized by sperm. In addition, the uterine lining (endometrium) is thickened to be able to receive a fertilized egg. If no conception occurs, the uterine lining as well as the egg will be shed during menstruation.

Mittelschmerz is a colloquial term for "ovulation pain" or "midcycle pain". About 20% of women experience mittelschmerz, some every cycle, some intermittently.

Dysmenorrhea Pain during menstruation

Dysmenorrhea, also known as painful periods or menstrual cramps, is pain during menstruation. Its usual onset occurs around the time that menstruation begins. Symptoms typically last less than three days. The pain is usually in the pelvis or lower abdomen. Other symptoms may include back pain, diarrhea or nausea.

Anovulation is when the ovaries do not release an oocyte during a menstrual cycle. Therefore, ovulation does not take place. However, a woman who does not ovulate at each menstrual cycle is not necessarily going through menopause. Chronic anovulation is a common cause of infertility.

The anovulatory cycle is a menstrual cycle by varying degrees of menstrual intervals and the absence of ovulation and a luteal phase. In the absence of ovulation, there will be infertility.

Natural family planning (NFP) comprises the family planning methods approved by the Catholic Church and some Protestant denominations for both achieving and postponing or avoiding pregnancy. In accordance with the Church's teachings regarding sexual behavior, NFP excludes the use of other methods of birth control, which it refers to as "artificial contraception".

Lactational amenorrhea Post-partum infertility due to breast feeding

Lactational amenorrhea, also called postpartum infertility, is the temporary postnatal infertility that occurs when a woman is amenorrheic and fully breastfeeding.

Hormonal contraception refers to birth control methods that act on the endocrine system. Almost all methods are composed of steroid hormones, although in India one selective estrogen receptor modulator is marketed as a contraceptive. The original hormonal method—the combined oral contraceptive pill—was first marketed as a contraceptive in 1960. In the ensuing decades many other delivery methods have been developed, although the oral and injectable methods are by far the most popular. Hormonal contraception is highly effective: when taken on the prescribed schedule, users of steroid hormone methods experience pregnancy rates of less than 1% per year. Perfect-use pregnancy rates for most hormonal contraceptives are usually around the 0.3% rate or less. Currently available methods can only be used by women; the development of a male hormonal contraceptive is an active research area.

Comparison of birth control methods

There are many methods of birth control. They vary in what is required of the user, side effects, and effectiveness. No method of birth control is ideal for every user. Outlined here are the different types of barrier methods, hormonal methods, various methods including spermicides, emergency contraceptives, and surgical methods.

Intrauterine device Form of birth control involving a device placed in the uterus

An intrauterine device (IUD), also known as intrauterine contraceptive device or coil, is a small, often T-shaped birth control device that is inserted into the uterus to prevent pregnancy. IUDs are one form of long-acting reversible birth control (LARC). One study found that female family planning providers choose LARC methods more often (41.7%) than the general public (12.1%). Among birth control methods, IUDs, along with other contraceptive implants, result in the greatest satisfaction among users.

CycleBeads Visual tool used for family planning

CycleBeads is a visual tool that was developed by the Institute for Reproductive Health at Georgetown University. This device helps women use the Standard Days Method, a fertility awareness-based family planning method.

Fertility testing

Fertility testing is the process by which fertility is assessed, both generally and also to find the "fertile window" in the menstrual cycle. General health affects fertility, and STI testing is an important related field.

The ovulatory shift hypothesis holds that women experience evolutionarily adaptive changes in subconscious thoughts and behaviors related to mating during different parts of the ovulatory cycle. It suggests that what women want, in terms of men, changes throughout the menstrual cycle. Two meta-analyses published in 2014 reached opposing conclusions on whether the existing evidence was robust enough to support the prediction that women's mate preferences change across the cycle. A newer 2018 review does not show women changing the type of men they desire at different times in their fertility cycle.

Menstrual suppression refers to the practice of using hormonal management to stop or reduce menstrual bleeding. In contrast to surgical options for this purpose, such as hysterectomy or endometrial ablation, hormonal methods to manipulate menstruation are reversible.

References

  1. 1 2 3 Grimes DA, Gallo MF, Halpern V, Nanda K, Schulz KF, Lopez LM (2004). "Family planning with methods based on fertility awareness | Cochrane". Cochrane Database of Systematic Reviews (4): CD004860. doi:10.1002/14651858.CD004860.pub2. PMC   8855505 . PMID   15495128.
  2. ↑ Baker, Fiona C.; Waner, Jonathan I.; Vieira, Elizabeth F.; Taylor, Sheila R.; Driver, Helen S.; Mitchell, Duncan (2001-02-01). "Sleep and 24 hour body temperatures: a comparison in young men, naturally cycling women and women taking hormonal contraceptives". The Journal of Physiology. 530 (3): 565–574. doi:10.1111/j.1469-7793.2001.0565k.x. ISSN   1469-7793. PMC   2278431 . PMID   11158285.
  3. 1 2 3 4 Coward, Kevin; Wells, Dagan (2013-10-31). Textbook of Clinical Embryology. Cambridge University Press. pp. 145, 156. ISBN   9780521166409.
  4. 1 2 Grimes, David A.; Gallo, Maria F.; Halpern, Vera; Nanda, Kavita; Shulz, Kenneth F.; Lopez, Laureen M. (October 2004). "Fertility awareness‐based methods for contraception". Cochrane Database of Systematic Reviews. 2004 (4): CD004860. doi:10.1002/14651858.CD004860.pub2. PMC   8855505 . PMID   15495128.
  5. 1 2 3 4 Cunningham, F. Gary (2014). Williams Obstetrics (24th ed.). New York: McGraw-Hill Education/Medical. pp. 696, 713. ISBN   9780071798938. OCLC   871619675.
  6. ↑ Trussell, James (2011). "Contraceptive failure in the United States". Contraception. 83 (5): 397–404. doi:10.1016/j.contraception.2011.01.021. ISSN   0010-7824. PMC   3638209 . PMID   21477680.
  7. ↑ Family planning : a global handbook for providers : evidence-based guidance developed through worldwide collaboration. Baltimore: Johns Hopkins, Bloomberg School of Public Health, Center for Communication Programs, INFO Project. 2011. ISBN   9780978856304. OCLC   776090067.
  8. 1 2 Taylor, Robert B. (2012-12-06). Taylor's Family Medicine Review. Springer Science & Business Media. p. 40. ISBN   9781461221524.
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