Menstrual Characteristics and the Risk of Spontaneous Abortion - 9 PLADs, China, 2013-2024.

WHAT IS ALREADY KNOWN ABOUT THIS TOPIC?: Menstrual irregularity is a hallmark clinical feature of polycystic ovary syndrome (PCOS), which is an established risk factor for spontaneous abortion. However, robust population-level evidence directly linking specific patterns of menstrual irregularity to spontaneous abortion risk remains lacking, as prior studies have been limited by small sample sizes.

WHAT IS ADDED BY THIS REPORT?: This nationwide study of 3.9 million women demonstrates that abnormal menstrual characteristics - including irregular menstrual cycles and abnormal menstrual period duration - are independent risk factors for spontaneous abortion, each exhibiting a dose-response relationship. The co-occurrence of long cycles and prolonged periods confers the highest overall risk.

WHAT ARE THE IMPLICATIONS FOR PUBLIC HEALTH PRACTICE?: These findings offer a scientific basis for formulating public health policies aimed at reducing spontaneous abortion (SA) risk, particularly in resource-limited settings. Menstrual characteristics constitute a simple, low-cost, and readily accessible tool for stratifying SA risk across the perinatal continuum - from preconception counseling through early pregnancy management.