After an IVF embryo transfer, most patients need progesterone. Some of our patients may ask, “Why do I need progesterone support after IVF embryo transfer? And I’ve heard that the protocols for luteal support for fresh embryo transfer and frozen embryo transfer seem to be different, what is the reason for this?” Let’s explain the reasons for this today. First of all, as you know, natural pregnancy does not usually require additional luteal support. After ovulation, the menstrual corpus luteum is formed, and after the fertilized egg is laid, hCG is secreted to stimulate the menstrual corpus luteum, which transforms into the corpus luteum of pregnancy, thus continuing to secrete progesterone to maintain the pregnancy until the placenta is formed. So how do you measure the need for corpus luteum support after an IVF embryo transfer? Let’s first look at the types of embryo transfer: fresh embryo transfer and frozen embryo transfer. Fresh embryo transfer refers to the transfer of oogenic embryos or blastocysts immediately after ovulation retrieval during the IVF treatment. Due to the lack of LH in the body after ovulation, the number of luteal cells decreases after egg retrieval and their function decreases accordingly, so they cannot secrete enough progesterone to maintain the pregnancy, then a certain dose of progesterone is needed. Frozen embryo transfer involves the use of embryo freezing technology to freeze and preserve the embryos after they have been cultured, and then at a suitable point in the menstrual cycle, the embryos are thawed and revived and transferred into the uterine cavity. However, unlike fresh embryo transfer, there are three endometrial preparation protocols for frozen embryo transfer: natural cycle, ovulation-promoting cycle, and artificial cycle. The luteal support required for each protocol is different according to the specific situation! 1. The natural cycle endometrial preparation protocol is mainly used for patients with regular menstruation and good quality follicles. However, some women may have their own luteal insufficiency when they undergo frozen embryo transfer after ovulation in natural cycle. Therefore, please follow your doctor’s advice whether you need luteal support or not. 2. The endometrial preparation protocol of the ovulation promotion cycle is mainly used for patients with irregular menstruation or regular menstruation with poor follicle quality. Because the ovulatory drugs can affect the luteal function, we will choose to supplement exogenous progesterone for luteal support in this case. 3. The artificial cycle endometrial preparation protocol mainly refers to the use of estrogen and progesterone to mimic the hormonal secretion of the menstrual cycle after descending regulation. Because the pituitary gland is inhibited by the use of pharmacological down regulation, there is no follicular growth and no corpus luteum, so there is no endogenous estrogen and progesterone, so a relatively larger dose of medication is required at this time. This method is usually used for patients with extremely irregular menstruation or the presence of endometritis or endometriosis. After the embryo transfer, the doctor will refer to the medical history, hCG level and doubling and progesterone level to determine the implantation status of the embryo, so as to decide whether luteal support medication is needed and the dose of medication, and also provide us with several options of medication: injection or vaginal administration. There is no big difference between “injections” and “pills” in terms of effectiveness. You can choose vaginal gel for self-administration, which is not only convenient, but also eliminates the pain, redness and swelling that may be associated with injections, and provides better compliance. Adequate luteal support is one of the key steps to achieve the goal of IVF success. Of course, each person’s situation is different and the protocol chosen is different. Even with the same protocol, there may be differences in the specific medications used, so it is important to listen to your doctor for details!