Menstrual cycle length identifies perinatal risk information beyond routine metabolic antenatal screening: a retrospective cohort study of 17,792 deliveries.

Authors

Qian Xia, Hong Mei, Dongmei Cao, Jingjing Rao, Feng Tang, Yun Xiang, Changzhen Li

Published in

Frontiers in endocrinology. Volume 17. Pages 1888560. Epub Aug 03, 2026.

Abstract

Preterm birth (PTB) and low birth weight (LBW) are leading causes of neonatal mortality and long-term morbidity. In China, the high prevalence of gestational diabetes mellitus (GDM) and thyroid dysfunction (TF) creates a metabolically complex obstetric environment in which identifying risk markers that add value beyond existing screening is a priority. Menstrual cycle length is routinely available, yet whether it provides risk information non-redundant with GDM and TF has not been rigorously examined.
Retrospective cohort of 17,792 consecutive singleton deliveries at a tertiary centre in Wuhan, China (2020-2024). Cycle length was recorded at intrapartum admission: short (<25d), normal (25-35d; reference), or long (>35d). Primary outcomes were PTB (<37 weeks) and LBW (<2,500 g). Three nested logistic models were fitted; stability across models was used to assess whether GDM and TF acted as strong confounders. Restricted cubic splines, additive interaction (RERI), population-attributable fractions (PAF), and five sensitivity analyses were used, with Benjamini-Hochberg FDR correction.
Long cycle (>35d; n = 1,810, 10.2%) was independently associated with PTB (aOR 1.36, 95% CI 1.12-1.64; FDR p = 0.006) and LBW (aOR 1.46, 1.18-1.78; FDR p = 0.002) after full adjustment for GDM and TF. Estimates were stable across progressive adjustment (PTB 1.34→1.36; LBW 1.42→1.46), indicating GDM and TF were not strong confounders. RERI for long cycle × GDM/TF crossed zero for both outcomes, excluding meaningful synergism. RCS showed a monotonic increase from ~30 days. PAF: PTB 3.1% (0.9-5.4%); LBW 3.9% (1.2-6.4%). The birth weight reduction (β = -33 g) attenuated at term (β = -8 g, NS), but long cycle was associated with higher odds of small-for-gestational-age (aOR 1.39, 1.11-1.73), including at term, indicating both earlier delivery and impaired fetal growth. Period length showed no association.
Long menstrual cycle length was associated with PTB and LBW, not materially attenuated by adjustment for GDM and TF, consistent with prognostic information non-redundant with metabolic screening; however, stable estimates cannot exclude residual confounding or establish an independent pathway. Because cycle length reflects the pre-pregnancy ovulatory interval, any clinical value would lie in collecting menstrual history before conception or in early pregnancy. These findings are hypothesis-generating and require prospective validation in community-based cohorts.

PMID:
42609307
Bibliographic data and abstract were imported from PubMed on 18 Aug 2026.

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