Determinants of the duration of lactational amenorrhoea among mothers in Alexandria

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Khadiga A. Khalil, Hoda Y. Atta, Faten A. Kamel and Randa M. Youssef

Abstract: A total of 300 women nursing a child aged 6 to 24 months were interviewed to determine their sociodemographic and biological characteristics, the antenatal care received, health problems encountered during pregnancy and the postpartum period, breast-feeding practices, child nutrition, and the duration of postpartum amenorrhoea. Multivariate Cox regression analysis revealed that seeking antenatal care, the time of initiation of breast-feeding, and the infant's age at the time of supplement introduction were the only significant independent determinants of the duration of the lactational amenorrhoea. To prolong the duration of lactational amenorrhoea, health education regarding good breast-feeding practices is of crucial value.

Facteurs déterminants de la durée de l'aménorrhée liée à la lactation chez les mères à Alexandrie

RESUME: Trois cents femmes allaitant un enfant âgé de 6 à 24 mois ont été interrogées pour déterminer leurs caractéristiques socio-démographiques et biologiques, les soins prénatals dont elles ont bénéficié, les problèmes de santé qu'elles ont rencontrés durant la grossesse et dans la période du post-partum, les pratiques d'allaitement au sein, la nutrition de l'enfant et la durée de l'aménorrhée après l'accouchement. L'analyse effectuée suivant la méthode à plusieurs variables en utilisant le modèle de régression de Cox a révélé que les consultations prénatales, le moment où l'allaitement au sein a commencé et l'âge du nourrisson au moment de l'introduction d'aliments de complément constituaient les seuls déterminants indépendants importants de la durée de l'aménorrhée liée à la lactation. Pour prolonger la durée de l'aménorrhée liée à la lactation, une éducation sanitaire concernant les bonnes pratiques d'allaitement maternel est d'une importance cruciale.

Introduction

Egypt is one of the most populous countries of the world. The rapid rate of population growth is a major threat to the nation's future. It impedes all development efforts and frustrates hopes for improving the quality of life for every Egyptian. The regulation of fertility offers the only solution to this problem. Many factors are proximate determinants of fertility, including contraceptive use [1-3] and breast-feeding [3]. In industrialized countries, virtually all married women resort to contraception at some time in their reproductive period. In contrast, the proportion reporting such use in developing countries is extremely low [4,5].

The lactational amenorrhoea method, which entails the continuation of full or nearly full breast-feeding and remaining amenorrhoeic during the first six months postpartum, was agreed by the Bellagio Consensus Conference to be adopted as an initial method of contraception [6]. Breast-feeding postpones the return of fertility by delaying ovulation and menses through the suppression of hormones that stimulate the maturation and release of ova [7,8]. The return of menses is a good indicator for regaining fertility and the need for an alternative method of contraception [9]. During the first six months postpartum, the lactational amenorrhoea method is 98% effective in preventing conception [6]. The cumulative six-month life table pregnancy rate was 0.45% among women who relied on lactational amenorrhoea as their only family planning method [10]. Furthermore, the analysis of data from nine prospective studies in different countries, including Egypt, concluded that, irrespective of the introduction of infant supplements, the probability of conception during the period of postpartum amenorrhoea was similar to that of modern contraceptive methods [11].

Since the lactational amenorrhoea method has been proved to be efficacious, this study was undertaken to reveal the determinants of the duration of lactational amenorrhoea among mothers in Alexandria.

Materials and methods

A total of 300 women from Alexandria participated in the study. Eligible women were those who were still nursing a child aged from 6 to 24 months. The cluster sample survey was adopted to select eligible women. Thirty clusters, the usual chosen number, were identified. From each cluster, 10 women meeting the inclusion criteria were selected, yielding a total of 300 women.

All women selected were subjected to an interview questionnaire designed to reveal: their sociodemographic and biological characteristics; the antenatal care received; the type of delivery; the adopted contraceptive method; health and psychosocial problems encountered during pregnancy and in the puerperium; breast-feeding practices and child nutrition; and the duration of postpartum amenorrhoea. The operational definition of the duration of postpartum amenorrhoea adopted in the present study was the time between childbirth and the onset of any vaginal bleeding or spotting, other than postpartum bleeding, whether or not the woman thought that it was similar to her pre-pregnancy menses [11].

Data were analysed using a microcomputer and the Statistical Package of Social Sciences (SPSS version 6.0). Kaplan-Meier survival, univariate and multivariate Cox regression analyses, which consider censored events, were performed. The former is used for categorial variables while the latter for both continuous and categorial ones, and to quantify the risk of resuming menstruation in association with the studied variables. The 5% level was chosen to judge the significance of the results obtained.

Results

For the 300 nursing mothers, the mean age was 29.62 + 4.85 years with a minimum of 18 years and a maximum of 49 years. Nearly half the mothers (44.3%) were illiterate or just able to read and write, while university graduates constituted 7.3% of the sample. Only 16.3% of the mothers were working women. At the time of the interview, 80.0% of the mothers had resumed their menses, the others were still amenorrhoeal. For the whole sample, the mean duration of lactational amenorrhoea was 5.53 months (SE = 0.36; 95% confidence interval [CI] = 4.83-6.24).

Table 1 presents the sociodemographic determinants of the duration of postpartum amenorrhoea. It reveals that mothers whose family income was less than 300 Egyptian pounds per month experienced a significantly longer duration of lactational amenorrhoea than those whose monthly family income was between 300 to 500 Egyptian pounds or was greater than 500 Egyptian pounds (log rank test = 9.47; P = 0.0088). On the other hand, neither the mother's level of education nor her working status was a significant predictor of the duration of lactational amenorrhoea.

The mother's biological characteristics, including her age, age at menarche, parity, as well as the interbirth interval, were not related to the length of postpartum amenorrhoea. However, it was observed that primiparae and those who reported an interbirth interval of more than four years experienced a shorter duration of lactational amenorrhoea, although the differences were statistically not significant (Table 2).

Receiving antenatal care and vitamin and mineral supplements during pregnancy were found to be significant predictors of the duration of postpartum amenorrhoea. A significantly shorter duration was encountered among women who had attended antenatal care (log rank test = 13.51; P = 0.0002) as well as those who received vitamin and mineral supplements during pregnancy (log rank test = 11.12; P = 0.0009). The estimated risk of resuming menstruation was 1.2 times higher among women who sought antenatal care (hazard rate = 1.28; 95% CI  = 1.09-1.51) and those who received vitamin and mineral supplements during pregnancy (hazard rate = 1.20; 95% CI = 1.05-1.37). It was observed that women who had had a normal delivery experienced a longer duration of postpartum amenorrhoea compared to those who had had an operative delivery. This longer period was also observed among women who used contraceptive methods other than hormonal ones. However, these differences were statistically not significant (Table 3).

The duration of postpartum amenorrhoea was not found to be affected by maternal ill-health or psychosocial problems encountered during pregnancy and in the postpartum period (Table 4).

Table 5 presents the duration of postpartum amenorrhoea among the mothers in relation to breast-feeding practices and child nutrition. The time of initiation of breast-feeding is a significant predictor of the duration of lactational amenorrhoea. The estimated risk of resuming menstruation increases by 1.1 times for each one-hour delay in the initiation of breast-feeding (hazard rate = 1.0968; P = 0.0025; 95% CI = 1.0428-1.1528). Moreover, the mean duration of lactational amenorrhoea was significantly longer among mothers who did not provide glucose to their infants immediately after delivery compared to those who did (log rank test = 9.58; P = 0.0020). Providing glucose to the neonate immediately after delivery is associated with an estimated risk of 1.2 of resuming menstruation (hazard rate = 1.18; 95% CI = 1.04-1.34). A longer duration of postpartum amenorrhoea was observed among mothers who introduced supplements in conjunction with breast-feeding after the age of four months compared to those who adopted such practice before that age, but the difference fell short of being statistically significant (log rank test = 3.34; P = 0.0678). However, the infant's age at the time of supplementation was a significant predictor of the duration of lactational amenorrhoea. The risk of resuming menstruation is 1.2 times higher for each month of accelerating supplement introduction (hazard rate = 1.16360; P = 0.0243). On the other hand, none of the other breast-feeding practices were related to the duration of lactational amenorrhoea.

Considering all significant predictors of the length of postpartum amenorrhoea, the multivariate Cox regression revealed that seeking antenatal care, the time of initiation of breast-feeding, and the infant's age at the time of supplement introduction are the only significant predictors of the duration of lactational amenorrhoea. The estimated risk of resuming menstruation is 1.1 times higher for each one-hour delay in the initiation of breast-feeding (hazard rate = 1.0700; P = 0.0474), and 1.2 times higher for each month of accelerating supplement introduction (hazard rate = 1.1704; P = 0.0300). In addition, women who attended antenatal care were 1.2 times more likely to regain their menses earlier compared to those who did not seek such service (hazard rate = 1.2082; P = 0.0464) (Table 6).

Discussion

Lactational amenorrhoea plays a key role in regulating fertility. The associated infertility takes two forms: a period of complete infertility during lactational amenorrhoea when ovulation is suppressed, followed by a variable period of lowered fecundity after the resumption of ovulatory cycles [12].

In the present study, considering women who had regained their menses and those who were still amenorrhoeal, the mean duration of lactational amenorrhoea was 5.5 months. This is similar to that reported by previous studies conducted in Alexandria [13] and Saudi Arabia [14] in which only women who resumed their menses were considered. A longer duration of postpartum amenorrhoea of 9.5 months was reported among Australian women [15].

The length of breast-feeding as a predictor of the duration of lactational amenorrhoea has been established by other studies [11,16]. The present study investigated other breast-feeding practices. The results indicate that early initiation of breast-feeding and refraining from providing the neonate with glucose immediately after delivery are associated with a significantly longer duration of postpartum amenorrhoea. In fact, a relation between early initiation of breast-feeding and the provision of glucose does exist. Mothers who did not provide their infants with glucose immediately after delivery initiated breast-feeding at a significantly earlier time (1.34 ± 0.945 hours) than those who did (2.40 ± 2.34 hours) (t = 5.009; P < 0.0001). This was further emphasized by the results of the multivariate analysis.

The key effect in the mechanism of lactational amenorrhoea is the suckling-induced changes in the hypothalamus sensitivity to the feedback effects of ovarian steroids [7]. This effect is exerted for a longer duration among women who breast-feed their infants frequently day and night [6,7] and on demand [5,17]. The association of such practices with the duration of postpartum amenorrhoea was not revealed by the present study. This could be attributed to the fact that 78.6% of the selected mothers provided their infants with supplements in conjunction with breast-feeding at a mean age of 3.79 ± 1.05 months. The study revealed that the infant's age at the time of the introduction of supplements is a significant predictor of the duration of postpartum amenorrhoea. This finding is in accordance with Mandini et al. [14] who reported a positive correlation between infant's age at the time of introduction of supplements and the length of postpartum amenorrhoea. The same was also reported by other investigators [5,17-21]. The introduction of supplements is associated with a reduction in the frequency and duration of suckling episodes, which increase the sensitivity of the hypothalamus to the positive feedback effects of estrogen and, in turn, the release of hormones that stimulate the maturation and release of ova [6,7].

Several studies have investigated the relation between maternal nutritional status and the duration of postpartum amenorrhoea, taking the mother's weight [22], triceps skin fold [23] as well as energy supplementation during pregnancy and lactation [24-26] as indicators. In the present study, family income, seeking antenatal care and receiving vitamin and mineral supplementation during pregnancy were considered indicators for maternal nutritional status. This is based on the assumption that higher family income is associated with increasing purchasing power of food items with higher nutritional value. Moreover, during antenatal visits, pregnant women undergo regular weight monitoring and receive health education related to their optimal weight and nutrition. It was revealed that all three variables are significantly associated with a shorter duration of postpartum amenorrhoea. This is in disagreement with a recent study conducted in Bangladesh reporting that maternal nutritional status plays a negligible role in the duration of postpartum lactational amenorrhoea, as it was nearly equal among women classified as well-nourished, moderately-nourished, and undernourished according to their weight [22]. On the other hand, other studies have indicated that well-nourished women, as well as undernourished ones given energy supplementation during lactation, have a shorter duration of lactational amenorrhoea [27-29] than those receiving no supplements [30-32]. This was documented by Lunn and his colleagues [24,25] and proved to be associated with a nearly 50% reduction in the plasma prolactin level. However, Kurz et al. [23], who considered maternal supplementation and triceps skin fold together with infant supplementation, revealed that maternal triceps skin fold plays a minor role and that the major determinant of the length of postpartum amenorrhoea is infant supplementation. They added that neither maternal supplementation nor any morbid conditions experienced influenced the duration of lactational amenorrhoea. In this study, the duration of lactational amenorrhoea was not affected by maternal morbid conditions during pregnancy and in the postpartum period. However, the care received during the antenatal period remains associated with a shorter duration of postpartum amenorrhoea.

In Africa, the amount of potential fertility reduced by the use of contraceptives is low [11]. It has been claimed that the lactational amenorrhoea method is responsible for preventing more pregnancies in developing countries than all other methods of contraception combined [5,33,34]. Kamel et al. [35] pointed out that, in Egypt, prolonged lactation and the associated period of infertility serves as the main limitation of population growth. This is particularly true in rural upper Egypt [3]. Because of its high acceptability, coupled with its safety, the lactational amenorrhoea method can be used as an initial method of contraception. This study concludes that improvement of breast-feeding practices, including refraining from providing the neonate with glucose after delivery, and the early initiation of breast-feeding, together with delaying supplement introduction, may have a great impact on lengthening the duration of postpartum amenorrhoea and fertility suppression.

References

1. Bongaarts J. A framework for analysing the proximate determinants of fertility. Population and development review, 1978, 4(1):103-32.
2. Bongaarts J. The fertility inhibiting effects of the intermediate fertility variables. Studies in family planning, 1982, 13(617):179-89.
3. Osheba IK. The proximate determinants of fertility change in the regions of Egypt (1980-88). Cairo Demographic Centre working paper. Cairo, Egypt, CDC, 1992.
4. Henry A, Piotrow PT. Age at marriage and fertility. Population reports, 1979, 4:107-56.
5. Morris L et al. Contraceptive prevalence surveys: a new source of family planning data. Population reports, 1981, 5:163-95.
6. Kennedy K, Rivera R, McNeilly AS. Consensus statement on the use of breast-feeding as a family planning method. Contraception, 1989, 39(5):477-96.
7. Labbock M. Breast-feeding and fertility. Mothers and children, 1989, 8 (suppl):1-3.
8. Hewie PW. The puerperium and its complications. In: Whitfield CR, ed. Dewhurst's textbook of obstetrics and gynaecology for postgraduates. Oxford, Blackwell Scientific Publications, 1987, 463-81.
9. Perez A et al. First ovulation after child birth: the effects of breast-feeding. American journal of obstetrics and gynecology, 1972, 114(8):1041-7.
10. Perez A, Labbock MH, Queenan JT. Clinical study of the lactational amenorrhoea method for family planning. Lancet, 1992, 339:968-70.
11. Kennedy KI, Visness CM. Contraceptive efficacy of lactational amenorrhoea. Lancet, 1992, 339:227-30.
12. Thapa S, Short RV, Potts M. Breast-feeding, birth spacing and their effects on child survival. Nature, 1988, 335:679-82.
13. El Sahn F, Darwish O. Breast-feeding and fertility. Part I. Lactational amenorrhoea. Journal of the Egyptian Public Health Association, 1992, 67(3-4):292-309.
14. Mandini KA et al. Lactational amenorrhoea in Saudi women. Journal of epidemiology and community health, 1994, 48:286-9.
15. Short RV et al. Contraceptive effects of extended lactational amenorrhoea: beyond the Bellagio consensus. Lancet, 1991, 337:715-7.
16. Newton N. Psychological differences between breast and bottle feeding. American journal of clinical nutrition, 1971, 24:993-1004.
17. Rodriguez-Garcia R. National family planning: a good option. Washington DC: Institute for International Studies in Natural Family Planning. Georgetown University, 1989.
18. Delvoye PJ, Demaegd M, Delogne-Desnoeck J. The influence of the frequency of nursing and of previous lactation experience on serum prolactin in lactating mothers. Journal of biosocial science, 1977, 9(4):477-51.
19. Morely P et al. Serum prolactin, gonado-tropins and estradiol in menstruating and amenorrheal mothers during two years lactation. American journal of obstetrics and gynecology, 1978, 130(6):635-9.
20. Hewie PW et al. Fertility after childbirth: postpartum ovulation and menstruation in bottle and breast-feeding mothers. Clinical endocrinology, 1982, 17:323-32.
21. Gray RH, Campbell OM, Apeto R. Risk of ovulation during lactation. Lancet, 1990, 335:25-9.
22. Ebrahim GJ. The contraceptive effect of breast feeding. An update [Editorial]. Journal of tropical pediatrics, 1991, 37:210-3.
23. Kurz KM et al. Effects of maternal nutritional status and maternal energy supplementation on length of postpartum amenorrhoea among Guatemalan women. American journal of clinical nutrition, 1993, 58:636-40.
24. Lunn PG, Prentice AM, Austin S. Influence of maternal diet on plasma levels during lactation. Lancet, 1980, 1:623-5.
25. Lunn PG, Watkinson M, Prentice AM. Maternal nutrition and lactational amenorrhoea. Lancet, 1981, 1:1428-9.
26. McCann MF, Liskin LS, Piotrow PT. Breast-feeding, fertility, and family planning. Population reports, 1981, 9:525-75.
27. Huffman SL et al. Nutrition and fertility in Bangladesh: breast-feeding and postpartum amenorrhoea. Population studies, 1987, 41:447-62.
28. Prema K et al. Nutrition-fertility interaction in lactating women of low income groups. British journal of nutrition, 1981, 45:461-7.
29. Huffman SL et al. Nutrition and postpartum amenorrhoea in rural Bangladesh. Population studies, 1978, 32:251-60.
30. Lunn PG et al. The effect of improved nutrition on plasma prolactin concentrations and postpartum infertility in lactating Gambian women. American journal of clinical nutrition, 1984, 39:227-35.
31. Delgado HL, Martorell R, Klein RE. Nutrition, lactation, and birth interval components in rural Guatemala. American journal of clinical nutrition, 1982, 35:1468-76.
32. Chavez A, Martinez C. Nutrition and development of infants from poor rural areas. Maternal nutrition and its consequences on fertility. Nutrition report international, 1973, 7:1-3.
33. Rosa FW. Breast-feeding in family planning. Protein Advisory Group bulletin, 1975, 5(3):5-10.
34. UNICEF. State of the world's children. Oxford, Oxford University Press, 1989.
35. Kamal I et al. Clinical, biochemical and experimental studies on lactation. Part I. Lactation pattern in Egyptian women. American journal of obstetrics and gynecology, 1969, 105:314-23.