In vitro fertilization, or IVF, involves combining an oocyte and sperm outside the body in a laboratory setting, hence the term “in vitro,” which comes from Latin meaning “in glass,” referring to early experiments conducted on glass plates. For those embarking on this journey, the means of calculating the probable due date in IVF differs from that of conventional pregnancy, for which the date of the last menstrual period is used as an indicator.
How to determine the moment of pregnancy in Assisted Reproduction
To calculate the weeks of pregnancy when assisted reproduction treatments are concerned, several technical points must be considered. The start of a pregnancy in assisted reproduction is counted either from the date of embryo transfer, or from the artificial insemination procedure, onwards, depending on the case.
As in vitro fertilization encompasses various modalities, the type of IVF can influence the calculation of the probable due date. The most common methods of IVF include conventional IVF and ICSI (intracytoplasmic sperm injection).
In conventional IVF, oocytes and sperm are combined in a culture dish, allowing fertilization to occur naturally. With ICSI, a single sperm is injected directly into the oocyte.
Then there’s artificial insemination, a technique in which sperm is introduced directly into the female reproductive tract to increase the chances of pregnancy. This is done in a controlled environment in a fertility clinic.
Therefore, the peculiarities of each treatment type need to be considered when calculating the weeks of pregnancy, however the calculation is more accurate because we know the timing of ovulation or fertilization and, in the case of embryo transfer, how many days old the embryo was at the time of transfer.
In IVF, ovulation occurs 36 hours after administering the ovulation trigger. Follicular puncture is then performed to retrieve the oocytes. The date of fertilization—whether via conventional IVF or ICSI—is counted as the embryo’s day zero. Embryos are cultured for a period of 2-6 days.
How to count the number of weeks of pregnancy in IVF. Calculation of the due date according to the type of IVF
Thus, depending on the type of technique performed, we can calculate the probable due date as follows:
- IVF treatment: the day of oocyte retrieval is counted as the “ovulation date”, equivalent to day 14 in a 28 day cycle.
- Artificial insemination: if the ovaries are stimulated with hormones, the insemination date is counted as equivalent to day 14 of a conventional cycle.
- Day 3 embryo transfer: if we consider day zero (equivalent to day 14 of the menstrual cycle in a conventional pregnancy) as the day of fertilization, the patient would be on day 17 of her menstrual cycle, so the date of the last period is counted 17 days before embryo transfer, and gestational weeks are counted from that date onwards.
- Day 5 embryo transfer: in this case, the patient would be on her day 19.
Probable due date calculator with IVF
However, we live in the digital age, and we no longer rely on mental calculations for these matters. There are tools which greatly facilitate the process and are designed to take into account the peculiarities of each type of fertility treatment. In addition to the probable due date, these calculators provide precise information on the expected foetal development at each stage of pregnancy. With the probable due date information, prospective parents embark on a new stage, a new beginning, which can become an achievable reality thanks to science.
