The contraceptive effect of breastfeeding

The fertility-reducing impact of breastfeeding, the hormonal mechanism of lactational amenorrhea, the cultural and individual behavioral variables that influence the hormonal mechanism and the duration of amenorrhea, and the policy implications of extending postpartum protection by using lactational amenorrhea as a complementary contraceptive are discussed. Recent studies indicate that the contraceptive effect of lactational amenorrhea is considerable, with use-effectiveness rates comparable to those of oral contraceptives, the condom, or the diaphragm; according to 1 estimate, breastfeeding provides 35 million couple-years of protection annually in developing countries, compared with 27 million provided by family planning programs. The contraceptive effect of breastfeeding is largely lost after the return of menstruation. The physiological processes by which lactation inhibits the ovulatory cycle in humans are poorly understood, although a close association is known to exist between frequent sucking, high prolactin levels, altered LH secretion, and amenorrhea. The length of the breastfeeding period and the timing of the addition of supplementary foods influence both the duration of amenorrhea and the frequency and intensity of nursing. Maternal age and demand vs. scheduled feeding may be secondary factors affecting the duration of amenorrhea. Cultural beliefs and norms regarding breastfeeding practices are of extreme significance in determining the duration of lactational amenorrhea. Flexible family planning programs which encourage the continuation of breastfeeding while promoting the use of appropriate contraceptive methods initiated when they will affect fertility are needed in developing countries.     

Statement on breast feeding,fertility and contraception

An important part of the human reproductive process, breastfeeding also plays a key role in infant nutrition while protecting the infant from exposure to infection. Breastfeeding also plays a major role in the natural regulation of fertility, but breastfeeding patterns are changing along with urbanization and lifestyle changes. These changes are tending towards a shortening of the duration of breastfeeding, a reduction in the daily frequency of breastfeeding episodes, and an earlier introduction of food supplements. Consequently, the risk of pregnancy during lactation has increased. The literature suggests considerable variability in the length of breastfeeding and postpartum amenorrhea and in the duration of lactational infertility among different populations. Both the return of ovarian activity and fertility depends on the time elapsed since delivery. Variables that play a primary role in the length of amenorrhea and infertility include: the duration of breastfeeding the frequency and duration of suckling; the administration of supplements to the infant; the mother's nutritional status; and geographic, social, and cultural factors. Knowledge of local breastfeeding practices and the associated risks of pregnancy should be a prerequisite for those counseling nursing women. All women should be advised and encouraged to breastfeed fully, as far as is practicable. Women also need to be informed that it is difficult to predict exactly the duration of lactational infertility for each woman. The timing of the introduction of contraception depends on the risk factors and some programmatic aspects, such as the possibility that the woman may not return after delivery or after the 1st postpartum visit as well as the type of contraceptive chosen. Current information on the influence of contraceptive methods -- IUDs, oral contraceptives, injectable contraceptives, norplant, barrier methods, periodic abstinence, and sterilization -- upon breastfeeding are summarized.     

Breast-feeding and postpartum ovulation

This paper reviews the evidence for the contraceptive effects of breastfeeding on postpartum ovulation. In developing countries breastfeeding prevents more pregnancies than all the other methods of contraception. In a detailed Edinburgh longitudinal study of 27 breastfeeding and 10 bottlefeeding mothers, the return of ovarian follicular development and ovulation was determined by several estimations of total urinary estrogen and pregnanedial excretion, respectively. In the bottlefeeding mothers the patterns of events after delivery was consistent. Basal prolactin levels fell to non-pregnant levels within 2-3 weeks postpartum. By 15 weeks all bottlefeeding mothers had resumed ovulation and menstruation. By contrast, all breastfeeding mothers who breastfed for a mean of 40 weeks maintained elevated basal prolactin levels for longer than the bottlefeeders. The mean time to 1st ovulation was 36 weeks with a range between 15-66 weeks postpartum. The infant feeding patterns showed striking differences between these mothers (33% of the whole group) who suppressed ovulation for more than 40 weeks postpartum and the rest of the mothers (67%) who ovulated before that time. The mothers who suppressed ovulation for more than 40 weeks not only maintained breastfeeding for the greatest number of weeks, but also suckled more frequently, breastfed for a longer total time each day, and maintained 1 or more night feeds for a longer time. After supplementary food was given there was a rapid increase in the number of mothers with evidence of ovarian activity and within 16 weeks of starting, 71% had evidence of follicular activity and 52% had ovulated. Mothers who introduce weaning food abruptly and reduce sucking rapidly will be more likely to experience an early return of ovulation and potential fertility. The mechanism of lactational infertility is not clearly understood. 45% of the completed menstrual cycles during lactation were anovular and of the 55% which were ovular, many were associated with defective luteal phases. The birth spacing effect of lactation is of great importance in communities where alternative contraceptive devices are not available or not acceptable. Breastfeeding is a complementary form of contraception.     

Lactational amenorrhea as a method of family planning in Egypt

Because of the potential importance of the lactational amenorrhea method (LAM) as a family-planning option in Egypt, we analyzed data from the 1995 Egyptian Demographic and Health Survey (EDHS) to study breastfeeding practices, use of contraception, reproductive history and sociodemographic factors for 5504 mothers with children under 3 years. According to the EDHS data, about 80% of Egyptian women breastfed for at least 6 months, and 40% breastfed for 15-18 months. Over half of breastfeeding mothers used no additional contraception. Thirty-six percent of mothers breastfeeding children younger than 6 months who reported using no additional contraception were exclusively breastfeeding and amenorrheic, but only 4% reported relying on breastfeeding for family planning. We also held eight focus group discussions with breastfeeding mothers from urban and rural Upper and Lower Egypt on their use of contraceptive methods, breastfeeding, lactational amenorrhea and LAM. Participants showed strong recognition of the contraceptive effects of breastfeeding but differed widely in their understanding of lactational infecundability and knowledge of LAM as a method. These results suggest that LAM would be widely acceptable to Egyptian women, but that an educational program about the method is needed.     

Lactational control of reproduction

In most mammalian species lactation suppresses fertility. There is no doubt that it is the suckling stimulus that provides the controlling signal, and, in human reproduction, this is the only truly physiological signal that suppresses fertility in normally nourished, healthy women. In breastfeeding women, the return of normal fertility follows a relatively well-defined path progressing through: an almost complete inhibition of gonadotrophin-releasing hormone/luteinizing hormone (GnRH/LH) pulsatile secretion in the early stages of lactation; return of erratic pulsatile secretion with some ovarian follicle development associated with increases in inhibin B and oestradiol; a resumption of apparently normal follicle growth associated with a normal increase in oestradiol, but often an absence of ovulation, or formation of an inadequate corpus luteum; and a return to normal ovulatory menstrual cycles. A key element in controlling the rate of this progression is the impact of the suckling stimulus on the GnRH pulse generator, a common feature of lactation in those species for which there is information. The variability in the duration of lactational amenorrhoea between women is related to the variation in the strength of the suckling stimulus, a unique situation between each mother and baby. Full breastfeeding can provide a reliable contraceptive effect in the first 6 to 9 months, but the precise mechanisms whereby the suckling stimulus affects GnRH pulsatile secretion remain unknown. Many studies on the hypothalamic pathways that might be involved in the translation of the neural suckling stimulus to suppression of hypothalamic GnRH secretion have been undertaken, principally in rats. In women, suckling increases the sensitivity of the hypothalamus to the negative feedback effect of oestradiol on suppressing the GnRH/LH pulse generator, a mechanism that appears to be common across species. In contrast, the role of prolactin in the control of GnRH appears to be species-dependent, with the importance varying from none to an important role in late or throughout lactation. In women, there is little evidence for a role of leptin, opioids or dopamine, although this may merely reflect the ethical dilemma of being able to give sufficient drug to test the system in the mother since these drugs will pass through the breast milk to the baby. Regardless of mechanism, practical guidelines for using breastfeeding as a natural contraceptive have been developed, which allows mothers to utilize the only natural suppressor of fertility in women as an effective means of spacing births.     

Lactational amenorrhoea and family planning

Scientists and policymakers at an international meeting in Bellagio, Italy, have concluded that the lactational amenorrhea method of family planning (LAM) can be recommended to help women space births. Based on a study of data from several thousand women in more than a dozen countries, including Nigeria and Rwanda, the group decided the following conditions were required to be simultaneously present to achieve a high degree of protection: 1) remaining amenorrheic; 2) being within six months of delivery; and 3) full or nearly full breastfeeding. Used in this manner, LAM was 98% effective. If any of the conditions should change, another method of contraception would have to be used. Infants older than 6 months need supplemental feeding, which typically decreases breastfeeding; however, in many of the reviewed studies, women who continued to breastfeed after 6 months together with supplemental feeding had a low rate of pregnancy, although higher than at six months. This may allow the extended use of LAM. Additional research is needed.     

New IPPF statement on breastfeeding,fertility and post-partum contraception

The International Planned Parenthood Federation International Medical Advisory Panel drew up the following statement in November, 1989. Breastfeeding is good for the infant. Antibodies passed to it from the mother protect it from infection. Patterns of breastfeeding are changing. Therefore, the risk of pregnancy is increased. Postpartum amenorrhea plays a major role in natural fertility regulation. Studies from around the world show a positive correlation between the length of breastfeeding and the length of lactational amenorrhea. Amenorrhea lasts longer in those who breastfeed more often at night and during the day. There is controversy over the effect of nutrition on postpartum infertility. Pregnancy and the puerperium are a good time for counseling on maternal nutrition, child spacing, breastfeeding, and contraceptive methods. Counseling nursing mothers about potential fertility during lactation should be based on local information. All women should be advised to fully breastfeed. Family planning programs should cooperate with maternity services in providing counseling and education for postpartum women who need contraception, for providing referral services, for producing educational resources, and in training health personnel. Postpartum contraception should be included in the training of traditional birth attendants. Women who do not breastfeed can select any contraceptive method. Mothers who nurse must not hurt success of lactation or the infant's health. Nonhormonal contraception should be the 1st choice for lactating women. IUDs do not harm infant growth or lactation. Postpartum insertions are appropriate, though care must be taken. Female sterilization can be conveniently done at this time. Barrier methods are reliable when used regularly. The failure rate should be lower when used after delivery. Progestagen-only contraception consists of progestagen-only pills, injectables, and Norplant. These do not affect quality and quantity of breast milk or length of lactation. They are suitable for those who do not wish nonhormonal methods. There are possible consequences, however, of the transfer of the steroid to breast milk. Hormonal methods should not be used earlier than 6 weeks postpartum. High and low dose oral contraceptives adversely affect the quality and quantity of breast milk. They also reduce duration of lactation. They should be withheld until 6 weeks after delivery, or until the infant is weaned--whichever comes first. The efficacy or periodic abstinence in nursing women requires further analysis.     

Breastfeeding: its relationship with postpartum amenorrhea and postpartum sexual abstinence in a Nigerian community

Breastfeeding, together with its two related postpartum variables--amenorrhea and abstinence--govern both the tempo and quantum of fertility in traditional African societies. Decline in breastfeeding also implies decline in postpartum amenorrhea and abstinence practice. Changes in breastfeeding practices in tropical Africa, therefore, has fertility implications and consequences. This paper examines how breastfeeding is functionally related to postpartum amenorrhea and abstinence in Ilorin, an urban community in Nigeria. Results indicated that the effect of breastfeeding on fertility, through its relationship with postpartum abstinence, might be more important than its effect through lactational amenorrhea in this society. This is more true among women with little or no education than among women with secondary or higher education. The population or family planning implications of these relationships are discussed.     

A study of breastfeeding and the return of menses and pregnancy in Karachi, Pakistan

A longitudinal study of breastfeeding women was conducted to determine whether breastfeeding frequency is associated with the length of postpartum amenorrhea. The data are also conducive to testing the guidelines of the "Bellagio Consensus" (i.e., that there is no more than a 2% chance of pregnancy during breastfeeding in the first six months postpartum in the absence of vaginal bleeding and regular supplements). Twenty-eight breastfeeding women were followed-up weekly in Karachi, Pakistan. The frequency of breastfeeding was found to be a poor correlate of the duration of amenorrhea. Thirty-six percent of the women became pregnant during the study. However, all were having menses and/or giving regular supplements before the estimated date of conception, consistent with the Bellagio Consensus. In countries such as Pakistan, where contraceptive use is low, active promotion is needed to prevent the further decline of breastfeeding in order to retain its contraceptive as well as other maternal and child health benefits.     

World population, family planning and development]

The 1991 world population report of the UNFPA projects a world population of 8.504 billion by 2025. The prevalence of the use of modern contraceptives increased from 9% in previous years to an average of 51% at the present time: to 70% in East Asia, to 60% in Latin America, but only to 17% in Africa. 20% of pregnancies are unwanted, the prevention of which would reduce the expected population by 2.2 billion people in 2100. Without birth control programs today there would be 412 million more people in Asia, Latin America, and Africa; and in 2100 1.48 billion would live on Earth instead of 10 billion forecast by the World Bank. The aim of UNFPA is to increase contraceptive prevalence form 51% to 59% by 2000: from 381 million users in 1991 to 567 million acceptors. Only 15% of men use contraceptives, although the prevention of sexually transmitted diseases especially AIDS makes the use of condoms highly advisable. In the report scant mention is made of breast feeding as a family planning method, although the Bellagio Consensus of 1988 states that if a woman almost exclusively breast feeds during lactation amenorrhea a more than 98% protection against pregnancy is offered during the 1st 6 months postpartum. During this period no additional contraception is necessary until the 1st menstruation occurs. Women in Bangladesh taking an oral contraceptive after delivery had shorter birth intervals than women exclusively relying on breast feeding. The Working Group of Medical Development Association issued guidelines concerning contraceptive methods including subdermal implant of levonorgestrel, although excessively strict standards can foil the contraceptive needs of the Third World. Their reproductive mortality is mainly determined by an extremely high maternal mortality rather than by complications from contraceptive use.     

Contraceptive choices for lactating women: suggestions for postpartum family planning

Both the fertility inhibiting effects of breastfeeding and the lactation inhibiting effects of hormonal contraceptives should be considered in developing postpartum family planning programs for lactating women. Because a high percentage of female contraceptive acceptors discontinue use within a year, the largest birth intervals may be achieved by delaying the initiation of contraception to take advantage of lactational infertility in the first postpartum months. Although evaluation of existing data on the effects of oral contraceptives on lactation is difficult, findings suggest that low-dose progestins may have a less detrimental effect on lactation than combined oral contraceptives. Depo-provera appears to enhance milk volume and duration of lactation, but the unknown side effects of transmission of steroids to the infant and changes in milk composition suggest caution in recommending it for nursing mothers. Results of research on possible effects of IUDs on lactation are conflicting and difficult to interpret, but possible mechanisms through prolactin secretion or oxytocin have been suggested for such an effect. Numerous methodological problems hamper efforts to evaluate evidence of the relationship of contraception to lactation to provide recommendations for family planning programs. The most prudent course where possible is to avoid giving hormonal contraceptives to the lactating woman. Where only hormonal contraceptives are acceptable, the best approach is probably to delay their use for at least 3 months postpartum to allow lactation to become established and the infant to mature.     

Contraceptive efficacy of lactational amenorrhea in urban Chilean women.

The contraceptive efficacy of breastfeeding was assessed in 236 healthy urban women who were followed at monthly intervals during the first postpartum year. Proportional hazard models were used to evaluate the influence of time postpartum, menstrual status and breastfeeding pattern upon the risk of pregnancy. Time and menstrual status had a highly significant effect on this risk. Those women who remained in amenorrhea had cumulative probabilities of pregnancy of 0.9% and 17% at 6 and 12 months postpartum, respectively. In those who recovered menstrual cycles, the risk rose to 36% and 55% at 6 and 12 months, respectively. Milk supplementation also increased significantly the risk when considered alone but not when time and/or menstrual status were included in the analysis. However, amenorrheic women who introduced bottle feeding, had a higher risk of pregnancy after 6 months postpartum than those who remained fully nursing. The analysis was unable to detect a significant influence of the nursing frequency. The results confirm that lactational amenorrhea is an effective contraceptive during the first six months postpartum. The first postpartum bleeding marks a great increase in the risk of pregnancy. Supplementation also increases the risk, particularly in amenorrheic women.     

Pharmacokinetic and pharmacodynamic studies of levonorgestrel-releasing intrauterine device

Intrauterine devices releasing 20 micrograms/day levonorgestrel were inserted in 10 women (ages 25-34). Bleeding and spotting patterns were recorded on a menstrual card during one year of follow-up. Blood samples were collected for radioimmunoassays of LH, estradiol (E2), progesterone (P) and levonorgestrel (LNG) and for sex hormone binding globulin (SHBG) 3 times a week during the 1st month of use, and twice a week during the 6th and 12th treatment months. Among the 10 women, two experienced irregular cycles with prolonged intermenstrual spotting, four had amenorrhea in the latter part of treatment months, while the other four had regular cycles. According to the serum levels of E2 and P, the hormone profiles were divided into four types of reaction: A) anovulatory, B) anovulatory but with high follicular activity, C) ovulatory but with luteal insufficiency, and D) ovulatory. Among the 29 treatment cycles, there were 10 D-type, 3 C-type, 13 B-type and 3 A-type of ovarian reactions: 44.8% of the cycles were ovulatory (C + D) and 55.2% were anovulatory (A + B). In general, serum levels of levonorgestrel were low in ovulatory cycles and were high in anovulatory cycles. The difference was statistically significant. There were marked individual differences. The decline of serum LNG from the 1st (492 pmol/l) to the 6th (320 pmol/l) treatment months was 34.9% on average. The amenorrheic cycles coincided mostly with the hormonal profile of ovulatory types, which indicated that the cause of amenorrhea is due to the local effect of levonorgestrel on the endometrium. The levonorgestrel levels were significantly correlated with serum SHBG, r = 0.8856, p less than 0.001, and with E2, r = 0.4661, p less than 0.05.     

Lactation and fertility.

During the last decade there have been many reports indicating a decline in breast feeding practices in the urban areas of developing countries. This decline might have adverse effects on maternal and child health. A study of 1079 urban hospital attending women was undertaken to evaluate their breast feeding practices. Prolonged (mean duration of lactation 19.8 months) and successful lactation (failure of lactation occurred in only 3.5%) was common among this group. But a trend toward shorter duration of breast feeding was found among educationally and economically better off segment. There was very good correlation between mean duration of lactation, lactational amenorrhea, and interpregnancy interval. Therefore, it is possible that decrease in duration of lactation might result in shorter interpregnancy interval. The duration of lactation appeared to be "fixed" for each individual irrespective of age and parity. This in turn resulted in "fixed" duration of lactational amenorrhea and interpregnancy interval under conditions of unhindered lactation and uncontrolled fertility. Conception during lactational amenorrhea was low (7.7%) but once periods were reestablished lactation offered very little protection against conception.     

Breastfeeding and contraception]

In the Netherlands many women stop breastfeeding in the first few months postpartum. In 1997, only 16.9% of all 3-month-old babies received full breastfeeding. One of the causes may be insufficient support by the medical profession. A second factor is that often combined oral contraceptives are prescribed to breastfeeding women. As it has been shown that estrogens in these contraceptives inhibit lactation, this is probably one of the reasons why breastfeeding frequently fails in this country. WHO advises not to use estrogens during lactation. According to recent research the lactational amenorrhoea method of contraception (LAM) is highly effective during the first 4 months postpartum. In the 5th and 6th month the effectiveness is strongly dependent on the accuracy by which the conditions are met. The medical profession should pay more attention to the support of breastfeeding and contraception in relation to each other.     

The effect of a breastfeeding education program on lactational amenorrhea in the Philippines

A study was conducted in two communities in the rural Philippines to determine whether breastfeeding mothers could intensify their nursing enough to increase the period of lactational amenorrhea. Women in one community were exposed to a breastfeeding education program before the birth and during lactation, while women in the other community served as a comparison group. Increased breastfeeding was observed in the group that received breastfeeding education, beginning in the sixth month postpartum. Bottle use began earlier and was more common in the comparison group, but the introduction of solid foods at five to six months was similar. No difference in the duration of postpartum amenorrhea (a proxy for the duration of infertility) was observed between the groups.     

Using complete breastfeeding and lactational amenorrhoea as birth spacing methods

The aim of this study was to evaluate the effectiveness of lactational amenorrhoea and to determine the relationship between extended breastfeeding and the return of fertility. Breastfeeding pattern, basal body temperature, cervical mucus, salivary ferning, vaginal blood discharge, frequency of sexual intercourse, and the presence of ovulation in the first cycle after the resumption of menses with ultrasonography were evaluated in 40 women. All subjects completed the study with only one case of incomplete breastfeeding. No pregnancies were observed. The mean number of feeding sessions and mean interval between sessions decreased significantly (p <0.01) during the first six months postpartum (7.5 +/- 1.3 after 60 days postpartum vs. 5.7 +/- 2.1 after 180 days, and 3.6 +/- 0.8 vs. 5.1 +/- 0.9, respectively). Eight women (20%) menstruated before weaning, but none had an adequate thermal shift, while 32 (80%) had their first vaginal bleeding after weaning with 12 (37.5%) registering an adequate thermal shift. Both basal body temperature and salivary ferning proved to be suggestive of ovarian activity, while mucus characteristics were not reliable in identifying fertile periods. Our study showed that breastfeeding associated with lactational amenorrhoea proved to be a good method of postpartum fertility control. Since the importance of supplementation is still debated, it is recommended that a "complete" breastfeeding program be used.     

Effect of levonorgestrel-releasing intrauterine device on hormonal profile and menstrual pattern after long-term use

In the present study 14 women after 6 years' use of levonorgestrel-releasing IUD were investigated for the changes of LH, progesterone (P), estradiol (E₂), prolactin (PRL) and serum binding globulin (SHBG) in relation to the levonorgestrel levels throughout a segment of 26–40 days with the aim of comparing the hormonal profiles with those during the first year of use of Lng-IUD. Ultrasound scanning was used to follow the development of follicles along with the RIA measurement of hormones. The results of serum LH, P and E₂ showed ovulation in 11 cases with either normal menstrual cycles (5 cases), prolonged or irregular cycles (4 cases) or with amenorrhea for 2–3 years (2 cases). One case showed insufficiency of luteal function and 2 cases showed anovulation but with follicular hyperactivity. Higher percentages of ovulatory cycles (78.5%) were found after 6 years of use. No case of complete suppression of ovulation was found. Anovulatory cycles only constituted 14.3%. Clinically, the development of follicles followed by ultrasound scanning further confirmed the hormonal findings. The persistent enlargement of follicles coincided with high levels of E₂. After 6 years of use, the serum levels of levonorgestrel were still maintained at mean levels of 314.26 pmol/L and 470.63 pmol/L in the ovulatory and anovulatory groups, respectively. It is concluded that over two-thirds of the cases have ovulatory cycles after long-term use of Lng-IUD; the contraceptive effect is mainly due to its local action on the endometrium, with much less effect on the ovarian function.     

闭经的诊断进展

女性正常月经依赖于下丘脑、垂体和卵巢及其激素诱导的子宫内膜之间的相互协调作用,其中任何一个方面出现功能障碍都可能导致闭经,影响生育。引起闭经的病因众多,明确诊断闭经的病因是治疗的关键。病史、体格检查、内分泌功能检查和辅助检查相结合可对闭经进行全面诊断。临床上最常见的闭经病因为下丘脑病变、多囊卵巢综合征、高催乳素血症和卵巢衰竭,综述临床常见闭经病因的诊断进展。