Tattoos are increasingly common among women of reproductive age, yet their potential systemic inflammatory effects and impact on fertility treatment outcomes are unknown. This prospective observational cohort study aims to evaluate whether the presence, size, duration, and ink characteristics of tattoos are associated with pregnancy outcomes following embryo transfer in women undergoing in vitro fertilization (IVF).

This is a single-center, prospective observational cohort study conducted at the McGill University Health Centre Reproductive Centre. Women undergoing IVF with planned fresh or frozen blastocyst embryo transfer will be enrolled and categorized based on tattoo presence and characteristics. Tattoo information will be collected using a standardized questionnaire and direct measurement. Participants will be followed for pregnancy and obstetric outcomes through medical chart review. The primary outcome is ongoing pregnancy rate following embryo transfer. Secondary outcomes include clinical pregnancy, biochemical pregnancy, miscarriage, ectopic pregnancy, and live birth.

Inclusion Criteria:

Women aged 21-40 years Undergoing IVF with planned fresh or frozen blastocyst embryo transfer Availability of good-quality blastocyst embryos Willingness to provide informed consent

Exclusion Criteria:

Significant untreated uterine abnormalities

≥3 prior failed embryo transfers Hydrosalpinx in situ BMI >40 kg/m² Age >41 years at embryo creation Submucosal fibroids in situ Use of medications affecting implantation (e.g., chronic steroids, metformin)

The study population consists of women aged 21 to 40 years undergoing in vitro fertilization (IVF) with a planned fresh or frozen blastocyst embryo transfer at a single academic fertility center. Eligible participants must have at least one good-quality blastocyst available for transfer and provide informed consent. Participants are prospectively followed and categorized based on the presence or absence of tattoos at the time of embryo transfer. Pregnancy and obstetric outcomes are assessed through review of medical records over the study follow-up period.

Individual participant data will not be shared because the study involves sensitive reproductive health information, and participants did not provide consent for public data sharing. In addition, the study is a single-center observational cohort, and data are retained in coded form in accordance with institutional ethics approval and privacy regulations.