A study of returning fertility after childbirth and during lactation by measurement of urinary oestrogen and pregnanediol excretion and cervical mucus production

Abstract

Longitudinal studies involving weekly measurement of urinary oestrogen and pregnanediol excretion were performed in 55 post-partum women to identify the patterns of returning fertility. The women kept diaries of breast-feeding episodes, mucus symptoms and times of bleeding; some recorded basal body temperature and acts of intercourse. The study represented a total time of 36 years (7-8 months per woman). The majority of the women were breast-feeding throughout the study. During lactation amenorrhoea, there was complete ovarian quiescence in twothirds of the subjects and minimal cyclic activity in the others. The first bleeds were associated with anovulatory ovarian activity in 40% of the women, with normal ovulation in 19%, with ovulation but short luteal phases in 25% and with ovulation but deficient luteal phases in 16%. The incidence of normal ovulatory cycles increased with time after delivery and with the number of cycles after delivery and eventually reached 85% even though many women were still breast-feeding at the time. Twenty-two pregnancies occurred, fourteen being unplanned: eight women were fully breast-feeding at the time of conception. Mucus symptoms correlated with the hormone values in approximately 60% of cycles. However, some women had symptoms which were difficult to interpret during their early cycles or potential fertility was not indicated by raised mucus scores or the presence of the peak mucus symptom. These problems together with the resulting confusion appeared to be the major causes for the unplanned pregnancies. Methods for coping with these problems are discussed.

Efficacy of a New Postpartum Transition Protocol for Avoiding Pregnancy

“…5 During the breastfeeding transition, cervical mucus changes often do not coincide with hormonal variations 6 or with ovulation as confirmed by ultrasound. 7 Temperature measurements may not be accurate in the first cycles after the return of menses, 8 and integrated rules of an NFP method that used mucus and temperature signs showed low specificity and positive predictive value but good sensitivity in predicting the return of fertility.…”

“…9 In addition, there is confusion among users about the interpretation of the natural signs of fertility during the breastfeeding transition, 10 especially if these women have had irregular cycles previously. 11 In studies that have investigated the efficacy of NFP during the breastfeeding transition, 4,6,[11][12][13][14][15][16][17][18] the pregnancy rates at 12 months have ranged from 11.1 13,15 to 24 per 100 women. 16 A more recent study of a new calendar-based NFP method (the Bridge Method), to be used once a woman has had her first menses, determined a pregnancy rate of 11.2 per 100 women over a typical 6-month period of use, 18 but it assumes that women use the lactational amenorrhea method (LAM) before this.…”

Current Medical Research Winter 2007/Spring 2008

“…Another earlier study by an Australian group found with 55 post-partum breastfeeding women that, after the first menses, 40% had anovulatory ovarian activity, 25% experienced ovulation but with short luteal phases, and 16% had normal ovulations with deficient luteal phases, i.e., luteal-phase lengths less than 11 days. 5 It is clear from the evidence provided by the above studies that there are many (25-40%) deficient (hormonally) and short (by days) luteal phases in the first post-partum menstrual cycle. There also is evidence that the pregnancy rate of women during the first post-partum menstrual cycle is much lower than expected in normal cycling women, i.e., 6-7% compared to 25%.…”

“…5 One study was conducted with 276 healthy, premenstrual U.S. women. 6 The researchers found that those women in "stressful jobs" had more than twice the risk of having shorter menstrual cycles than those women in non-stressful jobs.…”

Talking straight about emergency contraception

“…contraceptives such as the pill, patch, implant, injectable and ring, 15 and even breastfeeding, [16][17][18][19] ECPs may prevent pregnancy by delaying or inhibiting ovulation, inhibiting fertilisation, or inhibiting implantation of a fertilised egg. But, as a comprehensive review of the mechanism of action of levonorgestrel-only ECPs concluded: "At the same time, however, all women should be informed that the best available evidence is consistent with the hypothesis that their ability to prevent pregnancy can be fully accounted for by mechanisms that do not involve interference with post-fertilization events."…”