THC Drug Test. A marijuana drug test is the technical analysis of a biological specimen, such as urine, blood, hair, sweat or saliva, to determine the presence or absence of the active ingredients of marijuana (mainly THC) or its metabolites (breakdown products).t is important to note that urine tests are usually conducted to test for the presence of THC metabolites which indicates marijuana use. Blood tests are conducted when the amount of THC still present in the system has to be ascertained.
How is my due date calculated? Your due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (assuming a 28 day cycle). Note that your menstrual period and ovulation are counted as the first two weeks of pregnancy. If you deliver on your due date, your baby is actually only 38 weeks old, not 40.
The standard calculation is called N gele s Rule. This was developed in the 1850 s by a Dr. N gele, who determined that the average human pregnancy was 266 days from conception, or 280 days (40 weeks) from the start of the last menstrual period. To calculate this, begin with the first day of your last period (LMP).Add 7 days, then subtract 3 months.f ultrasound is performed in the first trimester, it can indicate fetal age within a range of 3 5 days. Later in pregnancy, it is less accurate. Up to 20 weeks, the margin of error is 7 10 days. By the third trimester, an ultrasound date can be off by as much as 3 weeks in either direction.