Dissociation between Cervical Mucus and Urinary Hormones during the Postpartum Return of Fertility in Breastfeeding Women

Abstract

Identifying the return of fertility with cervical mucus observations is challenging during the postpartum period. Use of urinary measurements of estrogen and progesterone can assist in understanding the return to fertility during this period. The purposes of this study were to describe the postpartum return of fertility by an analysis of total estrogen (TE) and pregnanediol glucuronide (PDG) profiles and to correlate these profiles with cervical mucus observations. Twenty-six participants collected urine samples during the postpartum period and recorded mucus scores. TE and PDG hormones were analyzed and compared with mucus scores. During amenorrhea, mucus reflected TE changes in only 35 percent of women; after amenorrhea, typical mucus patterns were seen in 33 percent of cycles. We concluded that postpartum mucus and hormone profiles are significantly dissociated but that monitoring urinary hormones may assist in identifying the return of fertility. We also identified different hormonal patterns in the return to fertility. The postpartum period is a challenging time for identifying the return of fertility. The purposes of this study were to describe the hormonal patterns during the return of fertility and to correlate these patterns with cervical mucus observations. Twenty-six postpartum women collected urine samples and recorded mucus scores. Urinary estrogen and progesterone hormones were analyzed and compared with mucus scores. Before the return of menses, mucus reflected hormonal changes in only 35 percent women and after first menses in 33 percent of cycles. We found that hormone profiles do not correlate well with mucus observations during the postpartum return of fertility.

Keywords: Breastfeeding; Estrone-3-glucuronide; Natural family planning; Postpartum; Pregnanediol.

Figure 1.

Representative symptoms chart from participant 111, from April to June 1986 (in French). Mucus coding is represented by a green color for “dry” mucus (Colombo score of 1, Marquette “Low” mucus), a yellow color for “moist, damp” mucus (Colombo score of 2 or 3, Marquette “High” mucus), and a blue color for “clear, slippery, stretchy” (Colombo score of 4, Marquette “Peak” mucus). Other signs, used in the symptothermal method, including temperature and cervix changes, are not shown here because they have not been analyzed in this study. (French terms: saignements = bleeding, glaire = mucus, douleurs abdominales = abdominal pain, pertes roses = spotting, sensibilité aux seins = breast tenderness, symptômes divers = miscellaneous symptoms, rapports sexuels = intercourse, infections = infections, dérangements = disturbances, jours après accou. = days after parturition, jours du calendrier = calendar days.)

Figure 2.

Representative hormone, mucus, and menses profile of a woman with prolonged ovarian quiescence and delayed ovulation (green, yellow, blue as described in Figure 1, red represents menses). Two arrows represent the end of full breastfeeding with the introduction of formula or solids (4.5 months) and complete weaning (11 months). The fact that full weaning occurred 6.5 months after the introduction of supplements indicates that the latter was very gradual and that breastfeeding was maintained at a rather intense level. This is recognized as a factor of delay in the return to fertility. The dotted line is the PDG threshold of 9 µmol/24 h as the biochemical criterion of ovulation. PDG = pregnanediol glucuronide.

Figure 3.

Representative hormone, mucus, and menses profile of a woman with follicular activity and delayed ovulation (green, yellow, blue as described in Figure 1, red represents menses). Two arrows represent the end of full breastfeeding with the introduction of formula or solids (3.0 months) and complete weaning (4.1 months). The short time span between the two landmarks indicates that breastfeeding intensity decreased rapidly, thereby probably stimulating reactivation of the hypothalamic–pituitary–ovarian axis. The dotted line is the PDG threshold of 9 µmol/24 h as the biochemical criterion of ovulation. PDG = pregnanediol glucuronide.

Figure 4.

Representative hormone, mucus, and temperature profile of a woman with relatively early ovulation prior to the end of full breastfeeding (green, yellow, blue as described in Figure 1, red represents menses). Two arrows represent the end of full breastfeeding with the introduction of formula or solids (5.0 months) and complete weaning (5.7 months). The dotted line is the PDG threshold of 9 µmol/24 h as the biochemical criterion for ovulation.