Natural vs Medicated Cycle

Natural Cycle Transfer (or Modified Natural)

A natural-cycle transfer works with the surrogate's own ovulation. The clinic tracks her cycle and transfers the embryo at the precise time her body is naturally prepared to implant.

What it typically looks like

• Cycle tracking begins (often ultrasound + bloodwork) to follow follicle growth and lining.
• Ovulation is confirmed either naturally (true natural) or with a trigger shot (modified natural).
• Progesterone may be added (commonly in modified natural) to support the luteal phase.
• Embryo transfer is scheduled based on the exact ovulation timing.
• Pregnancy testing follows about 9–12 days later (clinic-dependent).

Medicated Cycle Transfer (Programmed / HRT Cycle)

A medicated-cycle transfer uses prescribed hormones to prepare the uterine lining and control timing. The clinic builds the cycle so the uterus is ready on a planned transfer date.

What it typically looks like

• The surrogate begins estrogen to build the uterine lining.
• Monitoring checks the lining and hormone levels.
• Once optimal, the surrogate starts progesterone (often injections and/or suppositories).
• The transfer is scheduled based on the number of progesterone days required for the embryo's developmental stage (e.g., day-5 embryo).
• Pregnancy testing follows about 9–12 days later (clinic-dependent).

Why some clinics choose it

• Highly scheduleable—easier to coordinate travel, work, and clinic calendars.
• Useful when cycles are irregular or when the clinic wants maximum control over timing.
• Often the go-to approach for out-of-town coordination.