Hormonal Contraception and Endometrial Thickness in IVF/ICSI Cycles: A Multicentre Historical Cohort Study

Abstract

Objective

To study the association between previous use of levonorgestrel intrauterine system (LNG-IUS) and endometrial thickness (EMT) in women undergoing in vitro fertilisation (IVF)/intracytoplasmic sperm injection (ICSI) cycles.

Design

Multicentre historical cohort study.

Setting

Eight Danish public and private fertility clinics.

Population

12786 women aged 18–46 years contributing with an EMT measurement from 22 464 different IVF/ICSI treatment cycles between 2000 and 2021.

Methods

Exposure was previous use of LNG-IUS, combined oral contraceptive pills (OCPs), progeste-only pills (POPs), no/other contraception or combined, cumulated use of contraception when more contraceptives had been used during the inclusion period. Further, ever use of LNG-IUS was categorised into 0–3 years, > 3–6 years, > 6–9 years and > 9 years. Mixed effect logistic regression adjusted for age, BMI, smoking, educational level, total FSH dose and fertility clinic was used.

Main Outcome Measure (s)

EMT (< 7 mm ≥ 7 mm).

Results

Statistically significantly higher odds of EMT ≥ 7 mm were found for OCPs [odds ratio (OR) 3.53 (95% confidence interval (95% CI) 1.29–9.65)], POPs [OR 6.43, (95% CI 1.45–28.63)] and no/other contraception [OR 6.67, (95% CI 2.37–18.74]) relative to LNG-IUS in IVF/ICSI cycles. Further, all duration categories of ever use of LNG-IUS were associated with statistically significantly lower odds of obtaining an EMT ≥ 7 mm compared to no/other contraception.

Conclusions

In this study, previous use of LNG-IUS was associated with decreased endometrial growth in women undergoing IVF/ICSI.