The goal of this clinical trial is to compare the effects of oil-based contrast medium (OBCM) and water-based contrast medium (WBCM) during hysterosalpingography（HSG）on pregnancy outcomes in infertile women. The main question it aims to answer is whether an oil-based contrast medium improves fertility outcomes in infertile women. Participants were divided into those who received an oil-based contrast medium (ethiodized poppyseed oil) and a water-based contrast medium (Ioversol) based on a shared medical decision-making process between patients and healthcare providers. The two contrast agents used in this study are routinely employed in clinical practice and will not affect the participants' health. Participants are required to complete some clinical questionnaires before and after the HSG procedure to provide clinical information. Other than that, there will be no additional costs for participants.

Inclusion Criteria:

1. age ≥18 years
2. infertility for at least one year without the use of contraceptives.

Exclusion Criteria:

1. endocrine disorders, including Cushing's syndrome, hypothalamic amenorrhea, adrenal hyperplasia, diabetes, or thyroid dysfunction (except for well-controlled hypothyroidism with a TSH level between 0.3 and 4.0 mIU/L)
2. known allergy to contrast agents, specifically iodine
3. male partner infertility, defined as post-wash sperm motility <3 million/mL or <1 million/mL without sperm washing
4. contraindications for undergoing HSG
5. refusal to provide informed consent.

only IPD used in the publication of the results

Beginning 3 months and ending 3 years after the publication of results