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.
The common cold (also known as nasopharyngitis, rhinopharyngitis, acute coryza, head cold, or simply a cold) is a viral infectious disease of the upper respiratory tract which primarily affects the nose.
Cold viruses have a lot in common, but each type has its own style, too. Rhinovirus. This bunch is most active in early fall, spring, and summer. They cause 10%-40% of colds. You'll feel plenty miserable when you catch one, but the good news is they rarely make you seriously sick. Coronavirus.