Why is it important to measure pregnancy weeks?

Pregnancy weeks are measured for several reasons:

• Determining pregnancy progress: Counting in weeks helps healthcare professionals and expectant mothers monitor the fetus’s development and understand which stage the pregnancy is in.
• Estimating the due date: The 40th week of pregnancy is typically considered the full term, from which the estimated due date (EDD) is calculated.
• Planning medical check-ups: Certain tests and scans are scheduled according to the pregnancy week, such as the nuchal translucency scan, the second-trimester ultrasound, etc.
• Monitoring risks: Some risks and complications are associated with specific stages of pregnancy, so tracking the weeks is important for monitoring the health of both the mother and the fetus.
• Education and awareness: Pregnancy weeks provide a clear timeline for mothers to understand what to expect throughout their pregnancy.

These factors make tracking pregnancy weeks essential for proper monitoring and care
during pregnancy.

What is LMP?

LMP, or “Last Menstrual Period,” is a term used in obstetrics to refer to the first day of the last menstrual period before pregnancy. The LMP is significant because it serves as a reference point for calculating gestational age. From this date, doctors and midwives calculate pregnancy weeks, generally counting 40 weeks until the estimated due date.

How is the gestational week determined after IVF?
In the case of in vitro fertilization (IVF), the pregnancy weeks are calculated based on the date of embryo transfer and the age of the transferred embryos.

The method is as follows:

1. If the embryos are at day 3: Subtract 17 days from the embryo transfer date. This date is considered the first day of the last menstrual period (LMP) for the pregnancy.
2. If the embryos are at day 5: Subtract 19 days from the embryo transfer date, following the same principle (as LMP).

In this way, the calculation of pregnancy weeks is based on the estimated LMP determined by the embryo transfer date. Then, pregnancy weeks are counted as they would be in a natural conception, starting from the LMP onward.