Premenstrual Bleeding (PMB)

Premenstrual Bleeding (PMB) is a Creighton Model chart sign: brown spotting or light bleeding before a period starts. It appears in the days after Peak, when the chart should show no bleeding at all.

In a healthy cycle, the period starts cleanly. After ovulation, the corpus luteum, the gland that forms from the emptied follicle, produces progesterone. Progesterone keeps the lining of the uterus stable. When the corpus luteum shrinks at the end of the cycle, the lining sheds as a period. PMB disrupts this pattern. Spotting before the red flow means that the lining began to break down too early. The most common cause is low progesterone from a corpus luteum that stopped functioning too soon.¹ Adenomyosis, polyps, fibroids, and swelling of the uterine lining can also cause it.²³⁴ In women with infertility, spotting for two or more days before a period is strongly associated with endometriosis.⁵

Early breakdown of the lining is associated with difficulty conceiving and with early miscarriage. A Creighton Model chart makes PMB easy to recognize, cycle after cycle. A single episode of spotting may be a normal variation. A pattern that repeats on a well-kept fertility chart warrants further evaluation. It can point to luteal phase insufficiency or to a problem inside the uterus.

NaProTechnology-trained clinicians interpret PMB together with cycle-timed hormone tests and ultrasound findings. The goal is to identify the cause and restore healthy function after ovulation.