PREGNANCY CALENDAR

• In regularly menstruating women, ovulation and fertilization occurs average on 14 days (2 weeks) after the first day of the last menstrual period (LMP). In order to standardize the process, the gestational age is calculated beginning from the first day of the LMP . Accordingly, a woman who do not menstruate on the date she is expecting (4 weeks or 28 days after LMP) and is pregnant is considered to be pregnant for 4 weeks although she is actually 2 weeks pregnant. So, 40 weeks (280 days) of pregnancy is calculated If we count it from the first day of LMP. However, the actual gestational age is 38 weeks (266 days). We will use 40 weeks scala from now on. 

• It is normal to have slight deviations at the gestational age since not all women with the same LMP get pregnant at the same day and hour. For minor deviations, a gestational age correction is not required. But especially around 8-10 weeks, If the infant size is found to be significantly larger or smaller than expected, the expected birth date and  gestational age correction should be performed. Thus, the growth of the fetus  in the following weeks can be assesed more precisely.

• In women who get pregnant by in vitro fertilization, the calculation is done according to the day of egg collection (same day of fertilization) and an arbitrary LMP is calculated by going back  for 14 days.

• Term delivery is defines as delivery between  37-42 weeks. Before 37 is named as preterm and after 42 as postdate.