What happens if I miss a day of endometrial priming medication?

Endometrial preparation is one of the most important last steps in an assisted reproduction treatment before embryo transfer. This preparation is usually done by administering hormonal drugs. The goal is to create an optimal environment in the lining of the uterus (endometrium) for the embryo to implant and grow.

The endometrial preparation process may vary depending on the protocol used by your doctor, but generally involves the following:

1. Suppression of the menstrual cycle: in some cases, medication may be administered to suppress the natural menstrual cycle. This is done to control the timing of the embryo transfer. /li>
2. Hormonal stimulation: fter suppression of the menstrual cycle, hormonal drugs, such as oestrogens, can be administered to stimulate the growth of the endometrium. The most common dose is 4-6 mg per day, or its transdermal equivalent. These medications can be administered in the form of pills, patches or injections, as no one method has been proven to be better than another.
3. Administration of oestrogens. sthis is usually done for 2 weeks. This is intended to mimic the natural cycle, although longer than this does not seem to have any detrimental effect.
4. Endometrial monitoring: during the preparation process, regular ultrasound scans are performed to assess the thickness and appearance of the endometrium. They are also performed in order to prevent premature spontaneous ovulation, since, although oestrogen produces a pituitary inhibition, the risk is not completely eliminated. Monitoring helps to determine whether the endometrium is ready for embryo transfer.
5. Once the endometrium has reached the appropriate thickness and appearance, progesterone (in addition to oestrogens) is administered either vaginally (micronised natural progesterone, the most commonly used in Europe), subcutaneously or intramuscularly. The usual dose of micronised vaginal progesterone is 400-800 mg per day, divided into two or three doses. There is no difference in efficacy between the two doses, and it remains to be shown whether increasing the dose would be more effective in cases where serum levels are considered
6. Embryo transfer: once the endometrium reaches the appropriate thickness and appearance (between 7-8 mm thick), the embryo transfer is scheduled. The procedure consists of placing the embryo into the uterus through a catheter.

It is important to follow your doctor's instructions and take your medication as prescribed to ensure that your endometrial prep is effective.

If you forget to take your endometrial prep medication, it is important to tell your doctor as soon as possible, indicating which medication you have missed (oestrogen, progesterone or both depending on the stage of the endometrial prep) and how much. Your doctor will give you specific instructions on how to proceed in your particular case. In some circumstances, you may be instructed to take the missed dose as soon as you realise it, and then continue with your regular medication schedule. In other cases, you may need to adjust your medication