Breast Feeding Essay, Research Paper

BREASTFEEDING – NATURE’S WAY OF SPACING BABIES?

Introduction

The fertility regulating effect of breastfeeding has been known for underestimated. This has been due mostly to the lack of knowledge of the events associated with breastfeeding that determine its contraceptive effect. It is now known that breastfeeding per se is not a particularly effective or reliable means of contraception. On the other hand, the period of amenorrhea associated with breastfeeding, commonly referred to as lactional amenorrhea, provides an important degree of contraceptive effect.

Physiology of Contraceptive Effect of Breast Feeding

 Endocrine Responses to Breastfeeding

The physiological response to suckling at the breast is not local, but is mediated hormonally through afferent neural signals to the brain from receptors in the nipple. The secretion of two pituitary hormones, oxytocin and prolactin, into the circulatory system, marks the mother’s primary response to suckling. Leake et al. reported the continued presence of a vigorous oxytocin response in long-term (up to one year) breastfeeding. Oxytocin is secreted from specialised nerve endings in the posterior pituitary and participates in the milk ejection reflex, while prolactin is secreted from cells within the anterior pituitary and appears to be responsible for the co-ordination of the complex biochemical processes involved in milk production.

No reports were found that might attribute to oxytocin an ability to interact with the reproductive system. In contrast to the apparent lack of interaction of oxytocin, prolactin may affect reproduction at multiple sites including the hypothalamus, the pituitary and the ovaries. However it is not clear to what extent that any direct effects of prolactin are responsible for fertility suppression during lactation.

Gross and Eastman have developed a model of serum prolactin concentration during lactional amenorrhea, derived from data acquired from a prospective, longitudinal study of thirty-four breastfeeding mothers. Their data suggest that prolactin concentration might provide a sensitive index of the return of menstruation and fertility during lactation. According to their model, serum prolactin concentration at any week after delivery is dependent on:-

1. Some fixed early perinatal rate of decline in concentration.

2. The number of weeks that unsupplemented breastfeeding continued.

3. The number of weeks of supplemented breastfeeding.

4. The number of weeks since the onset of weaning.

The model assumes that ovulatory cycles would ensue once the average serum prolactin concentration has fallen to a threshold below which ovulation suppression no longer can be maintained.

The hypothesis that the pattern of suckling stimulation determines the extent of the fertility suppressing effect was suggested in a review by McNeilly et al. Wood et al. developed a similar hypothesis in relation to their study of the Gainj people of New Guinea. The authors suggested that a pre-nursing concentration of prolactin will be re-established in about three hours unless another nursing episode intervenes. They base their reasoning on the observation thta serum prolactin concentration peaks within thirty minutes of initiation of nursing and the understanding that prolactin is removed from circulation with a half-life of about thirty minutes. According to their observations, a typical pattern for a Gainji infant would be three minutes suckling every half-hour, whereas an American infant might be in a schedule of thirty minutes every five hours, on the average. Wood et al. predict that the pattern of short, frequent bouts would produce higher average and basal prolactin concentrations and thus prove to be more effective in suppressing fertility than longer duration , infrequent bouts of nursing.

It is difficult to see hoe the basal and average prolactin concentrations could be dependent on the pattern of suckling unless there exists refractoriness or some other form of non-linearity in the mechanism of prolactin synthesis and release. A possible theoretical base for understanding this problem has been given by the experimental work or Charles Grosvenor and his associates at the university of Tennessee. Grosvenor’s group found that a metabolite of TRH, cylco-his-pro, inhibits the transformation of prolactin in the pituitary from a pre-releasable to a releasable form. They theorise that TRH released by the hypothalamus in response to the suckling inhibits the release of dopamine from the TIDA (tubero-infundibular dopaminergic) neurones of the hypothalamus, thus removing the chronic inhibition of the transformation of prolactin from its pre-releasable to its releasable form. However, TRH is quickly metabolised, yielding cyclo-his-pro that blocks further transformation. After an interval has elapsed between suckling bouts, the refractory state abates. A new suckling stimulus then is capable of triggering another prolactin release and an additional prolactin transformation in preparation for the next stimulus-release episode.

 Hormonal Responses not Mediated by Prolactin

McNeilly et al. proposed the existence of a GnRH (gonadotrophin releasing hormone) pulse generator located in the hypothalamus that can be disrupted by input from the mammary nerve when stimulated by suckling. This disruption would depress reproduction since pulsatile secretion of GnRH is necessary for the development of the episodic release and eventual surge in LH (lutienizing hormone) secretion. The LH surge is considered to be the necessary trigger for rupture of the ripened ovarian follicle, i.e. ovulation. In their view, the suckling stimulus is the key factor in the endocrine control of lactational infertility and anything that undermines or reduces this stimulus will result in as resumption of ovarian activity with a variable return in fertility.

Post-Partum Anovulation in Nursing Mothers

The length of the post-partum anovulatory period in nursing mothers has been reported to vary widely among different populations and a variety of mechanisms determining ing the length of the anovulatory interval has been considered by several investigators. Dominant among the hypotheses proposed have been :-

 The Nutritional Hypothesis – Extended post-partum amenorrhea seen in poor developing countries is due to undernourishment and insufficient stores of body fat.

 The Behaviour Hypothesis – Mothering and nursing practices play the primary role in determining the length of post partum amenorrhea.

Taylor et al. have analysed breastfeeding and ovulation data from seventy-two mothers. A proportional hazards model of the data strengthened the hypothesis that a pattern of short frequent bouts of nursing define a risk-set of women less susceptible to post-partum ovulation than those who choose to nurse on a schedule of relatively lengthy and infrequent bouts. In contrast, no effect of maternal weight for height on the month-specific rate of post-partum ovulation could be detected in the study population comprised of American mothers trained in self-observation of fertility signs.

A brief summary of their results follows.

The proportion of the study population remaining anovulatory as a function of the number of months since childbirth.

1.00

0.75

0.50

0.25

0.00

0 5 10 15 20 25

y-axis : “Proportion remaining Anovulatory”

x-axis : “Months Post-partum”

FIG. 1. Post-partum anovulatory intervals for the study population ranged from 5.1 to 26.6 months. The mean interval was 14.1 months with a standard deviation of 5.2 months. The median anovulatory interval was 13.9 months, with the first and third quartiles occurring at 10.8 and 16.7 months respectively.

Median nursing bout length as a function of the time since childbirth.

40

35

“Bout 30

Length”

(min) 25

20

15

10

5

0

0 5 10 15 20 25

“Months post-partum”

FIG. 2. No direct relationship between the length of individual nursing bouts and ovulation susceptibility could be established.

Median of interbout interval as a function of the time since childbirth.

6

5

“Inter-

bout 4

interval”

3

2

1

0

0 5 10 15 20 25

“Months post-partum”

FIG. 2. Hazard analysis of ovulation-time data showed that the length of time between nursing bouts is the single most significant measure of breastfeeding behaviour influencing the timing of a mother’s first post-partum ovulation.

Lactaional Amenorrhea Method

The use of lactational amenorrhea during the first six months post-partum by fully or nearly fully breastfeeding women is referred to as the lactational amenorrhea method or LAM.

It is important to understand the difference between using only breastfeeding and the use of LAM for fertility regulation as the contraceptive effectiveness is substantially different. LAM is an efficient short-term method of family planning, based on WHO sponsored research. At a conference held in Bellagio, Italy in 1988 , a consensus document was produced which concluded that a woman is 98% protected from pregnancy when:

 She is fully or almost fully breastfeeding.

 The baby is less than six months old.

 Menstruation has not returned.

When these criteria no longer apply, the chances of pregnancy are increased and the woman has to consider another family planning method. The criteria for breastfeeding have to be clearly defined to ensure the suppression of fertility. The Bellagio conference stated

“They (the mothers) should be informed how to maximise

the anti-fertility effects of breastfeeding to prevent

pregnancy…..”

What that means is that only ‘ecological’ breastfeeding provides extended post-partum infertility. This is a form of baby care which is characterised by constant mother-baby togetherness and frequent nursing, both by day and by night. Fully breastfeeding means that the baby is fed by his mother on breast milk alone without the addition of other milk, fruit juices or solids. Water may be given. The baby will be fed on demand and will suckle for nourishment and comfort instead of having a dummy. This frequent suckling is important to maintain fertility during lactation and will be discussed later. It is also important that the feeding technique should be good if fertility is to be suppressed by breastfeeding. Any reduction in breastfeeding will increase the chances of pregnancy and the return of menstruation, or six months post-partum signals the end of protection from LAM.

A multi-centre study of LAM was carried out to determine acceptability, satisfaction and utilisation in ten different populations, and to confirm the efficacy of the method. The overall satisfaction with LAM was 83.6% and continuation with another method of family planning was shown to be 67.6% at nine months post-partum. Knowledge and understanding were high, ranging from 78.4 to 88.6% for the three criteria. LAM can be used with a high level of satisfaction and success by women in a variety of cultures, health care settings, socio-economic strata, and industrial and developing country settings.

Advantages and Disadvantages of LAM

 Advantages

1. Breastfeeding does not cost anything and can be convenient.

2. It is the best way to feed a baby, both nutritionally and from the bonding perspective.

3. Breastfeeding burns calories, thereby helping the mother to return to her original weight.

4. It can be discontinued at any time, without the intervention of a health professional.

5. When used properly it is as effective as using a barrier method of contraception.(e.g. condoms, diaphragm etc.)

 Disadvantages

1. It is not an effective method of contraception after the return of menstruation, or six months post-partum.

2. The mother must be willing to breastfeed her baby every time that he/she is hungry to ensure that fertility is suppressed.

3. LAM does not protect against sexually transmitted diseases.

4. Breastfeeding can produce vaginal dryness.

5. Some women may develop soreness or infections in their nipples or breasts.

Conclusion

Numerous studies have shown thta breastfeeding extends the length of the post-partum anovulatory interval over that experienced by bottle feeding mothers. Some of these studies showed that the length of the anovulatory interval experienced depends on the style of breastfeeding that the mother practices. Supplementation and scheduling of breastfeeding, as well as episodes of mother/baby separation, all increase the mother’s chances of ovulating after childbirth.

The reproductive system is placed under inhibitory control, either by suckling acting directly at the hypothalamic level to suppress the HPO-axis, or through prolactin and its multiple levels of influence on the HPO-axis.

LAM can be a useful way to time the commencement of a second, less temporary contraceptive method. This was confirmed by a conference on lactational infertility (Bellagio, Italy, 1988) which stated:

“…Post-partum women should be offered a choice of using

breastfeeding as a means of family planning, either to help

achieve optimal birth spacing, or as a way of delaying the

introduction of other contraceptives…”

The results from the multi-centre study of LAM verify that it is acceptable and ready for widespread use, and should be included in the range of services available in maternal and child health, family planning and other primary health care settings.

Journals

 Rivera.R., “The use of lactational amenorrhea as a fertility regulating method,” Advances in Contraception, vol.12(3), pp. 179- 185, 1996.

 Jackson.R.L., “Ecological breastfeeding and child spacing,” Clinical Pediatrics, vol.27:8, pp.373-377, August 1988.

 Kippley.S.K. & Kippley.J.F., “The relation between breastfeeding and amenorrhea : report of a survey,” Journal of Tropical Pediatrics and Environmental Child Health, vol.23, pp.239-245, 1997.

 Habicht.J.P., Davanzo.J., Butz.W.P. & Meyers.L., “The contraceptive role of breastfeeding,” Population Studies, vol.39, pp.213-232, 1992.

 McNeilly.A.S., Robinson.I.C.A.F., Houston.M.J. & Howie.P.W., “Release of oxytocin and prolactin responses in long-term breastfeeding,” Obstetrics and Gynecology, vol.62, pp.567-589, 1992.

Books

 Howie.P.W., “Synopsis of research on breastfeeding and fertility,” Breastfeeding and natural Family Planning, ed.Mary Shivanandan, pp.7-21, KM Associates, Bethesda, MD, 1986.

 La Leche League International, “The Womanly Art of Breastfeeding,” La Leche League International, Franklin Park, IL, 1981, 3rd edition.

 McNeilly.A.S., Glasier.A. & Howie.P.W., “Endocrine control of lactational infertility,” Maternal Nutrition and Lactational Infertility, ed. Dobbing.J., pp.1-19, Nestle Nutrition, Raven Press, New York, 1985.

 Bongaarts.J. & Potter.R.G., “Fertility, Biology and Behaviour,” Academic Press, New York, 1983.

 Kippley.S.K., “Breastfeeding and Natural Child Spacing : How Ecological Breastfeeding Spaces Babies,” The Couple to Couple League International, Inc., Cincinnati, 1989.