A reproductive endocrinologist completed residency in obstetrics and gynecology and then a fellowship in reproductive endocrinology and infertility. REIs lead fertility evaluation and treatment, including IUI and IVF. Some health plans allow you to book directly; others require a referral first.
Fertility Glossary
Reproductive endocrinologist (REI)
An OB-GYN with additional fellowship training in fertility and hormone disorders.