The chance of conception during lactation

Ginneken, Jeroen K. Van

doi:10.1017/s0021932000023828

Cited by 41 publications

(12 citation statements)

References 22 publications

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“…Since a successful parturition is followed by an interval of lactation that may extend into the next breeding season, it may be that the reduction in pregnancy rate at the second year, which again is more pronounced for the earlymaturing females, may be due to the effects of the lactational period following first pregnancy. There is evidence from studies on human females that prolonged lactation does delay the next ovulation (Knodel, 1977;Van Ginneken, 1977). Since rhesus monkeys are seasonal breeders, a failure to conceive during one mating season imposes a 12-month interval to subsequent ovulation.…”

Section: Discussionmentioning

confidence: 99%

Consequences of first pregnancy in rhesus monkeys

Wilson

Walker

Gordon

1983

American J Phys Anthropol

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Female primates have been thought to be reproductively disadvantaged during their early reproductive years. In order to assess the effects of first pregnancy on a female's subsequent reproductive activity, the breeding records of female rhesus monkeys (Macaca mulatta) living in provisioned, outdoorhoused, social groups were examined with respect to age of sexual maturity. Of the 78 colony-born females contributing to the analysis, 20.5% had their first parturition a t 36 months of age. The majority of females, 73.1%, had first parturition a t 48 months; 6.4% did so at 5 years of age. Ofthe early-maturing females, 75% were from high-ranking matriarchies. But high social rank did not guarantee early first parturition, as 55.6% of the females from high-ranking matriarchies had first birth at 48 months. An examination of outcomes of successive pregnancies revealed that both early-and typical-maturing females experienced a significant decline in live births, owing to a significant increase in sterile years, for the reproductive year following a successful first parturition. This decline was even more pronounced for early-maturing females. The frequency of birth tragedies remained constant throughout the second and succeeding pregnancies. Thus, the capacity to conceive was reduced for some females in the reproductive year following their first pregnancy. Those females that did conceive in the year following a successful first pregnancy had a significantly longer interbirth interval between their first and second parturitions than between subsequent parturitions. Sex of offspring at first parturition did not influence reproductive outcome in the following year. The nutritional costs of lactation associated with a successful first pregnancy may preclude or delay ovulation the following year, and this effect may be greater for young females that are still in a growth phase at first pregnancy. Although these early-maturing females had proportionally fewer live births during their second reproductive year, they were equal to their age-mates when compared on the basis of offspring produced by a female at any given age. In addition, since early-maturing females have offspring entering the breeding pool a full year earlier, they may not necessarily be reproductively disadvantaged.

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Section: Discussionmentioning

confidence: 99%

Consequences of first pregnancy in rhesus monkeys

Wilson

Walker

Gordon

1983

American J Phys Anthropol

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“…The ultimate test of fertility is pregnancy and several reports have demonstrated that breast feeding increases the interval between pregnancies (for summary, see van Ginneken, 1977). For example, two studies compared the time to next conception in nursing and non-nursing mothers from Alaskan Eskimo (Berman, Hanson & Hellman, 1972) and rural Indian populations (Potter, New, Wyon & Gordon, 1965).…”

Section: Methods Of Assessing Lactational Infertilitymentioning

confidence: 99%

Effect of breast-feeding patterns on human birth intervals

Howie¹,

McNeilly²

1982

Reproduction

175

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An adequate inter-birth interval is of great importance because it enables a mother to recover her physical and emotional strength between pregnancies and confers upon the child advantages of better health and development (Morley, 1977). Breast feeding is the naturally evolved method of ensuring an adequate inter-birth interval but the contraceptive effect of breast feeding has been largely dismissed in developed countries on the grounds that it is an unreliable method of family planning for individual mothers (Kamal et al., 1969). The use of artificial contraception varies very widely in different countries, being much higher in developed nations than in the poorer developing countries (Text- fig. 1). Where the use of artificial contraceptives is low, breast feeding is the most widely used method of birth spacing and assumes major demographic importance. It is important, therefore, that the factors controlling lactational infertility should be understood so that guidelines can be developed which will allow mothers to maximize the birth-spacing effect of breast feeding to their own advantage. In developed countries, few mothers choose to rely on breast feeding for family planning although an increasing minority may find breast feeding to be an attractive method of spacing their families, thereby avoiding the potentially adverse side-effects of currently available contraceptive methods. A better understanding of how breast feeding mediates its birth-spacing effect may lead to the development of new contraceptive methods which will try to imitate this naturally evolved method of fertility control (McNeilly, 1979). Developed countries Middle Income countries Poor countries USA UK JAPAN POLAND MEXICO PERU DOMINICAN REPUBLIC JORDAN INDIA PAKISTAN GHANA ZAMBIA =1 =1 ) 20 40 60 % Contraceptive users 80 100 Text-fig. 1. Contraceptive usage by married women aged 15-44 years in different countries by economic status.

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“…The significance of breast-feeding as a method of contraception was studied in rural Zambia by Wenlock (1977), who noted that breast-feeding has a contraceptive effect and that the peak of new conceptions occurred between 25 and 27 months postpartum. Carballo (1977) stated that the potential role of lactational amenorrhoea as a child-spacing mechanism should not be underestimated, and he contended that postpartum lactational amenorrhoea, though it does not offer complete protection against conception for individual mothers, is of value when a whole community is considered, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…Introduction of breast milk substitutes into babies' diets adversely affects the duration of postpartum amenorrhoea. Lactational amenorrhoea is very long only if breast-feeding is complete, successful and unsupplemented (Jelliffe & Jelliffe, 1972;Van Ginneken, 1977). In some parts of Central Africa the positive contraceptive effects of the factors mentioned above on postpartum lactational amenorrhoea are further reinforced by sexual abstinence (Rosa, 1975;Mosley, Osteria & Huffman, 1977).…”

Section: Introductionmentioning

confidence: 99%

Postpartum Lactational Amenorrhoea as a Means of Family Planning in the Sudan: A Study of 500 Cases

Adnan

Bakr

1983

J. Biosoc. Sci.

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SummaryThe lactational histories of 500 Sudanese women were studied retrospectively to examine postpartum lactational amenorrhoea as a method of family planning. Particular attention was given to the factors affecting postpartum lactational amenorrhoea, including supplementary feeding and the use of modern contraceptive methods. Breast-feeding was overwhelmingly practised (90%) among this sample, which was roughly representative of the Sudanese population as a whole. The prevalence of amenorrhoea among this group of lactating women was quite high (73%). Duration of lactational amenorrhoea ranged from 2 to 36 months with a median of 12 months.Introduction of supplementary feeding had little effect on lactational amenorrhoea up to the 9th month of breast-feeding. Beyond the 12th month of breast-feeding, lactational amenorrhoea was significantly prolonged by postponing the introduction of supplementary feeding until the 4th month or later.Ovulation, and hence conception, during lactational amenorrhoea was unpredictable. It occurred as early as the 3rd or as late as the 36th month postpartum. Conceptions interrupting lactational amenorrhoea soon after delivery (3–9 months) were more frequent among primiparous women. The failure rate of lactational amenorrhoea as a contraceptive was 8·4%. Though extremely high compared to that of the pill, lactational amenorrhoea was more useful as a fertility control mechanism because, in this study, a high proportion of women initiated pill use, but soon discontinued it because of side effects. Modern contraceptive practice was not prevalent. Amenorrhoeic mothers accepted the pill after the 6th month postpartum (41%), compared to lactating mothers whose menses had returned who started it much earlier. Forty-nine percent of the women studied relied completely on the protection of lactational amenorrhoea. Fifty-seven percent of all lactating women who used the combined pill reported a reduction in milk production. There are several policy implications of this study.

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The chance of conception during lactation

Cited by 41 publications

References 22 publications

Consequences of first pregnancy in rhesus monkeys

Consequences of first pregnancy in rhesus monkeys

Effect of breast-feeding patterns on human birth intervals

Postpartum Lactational Amenorrhoea as a Means of Family Planning in the Sudan: A Study of 500 Cases

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