Page 3 â Measuring time in different cultures. Measuring time. Scientifically, the year is a complete cycle of seasons. A year is when the earth completes one full orbit of the sun. Its length is measured from one spring equinox to the next spring equinox. Measuring the time of year was important to most people. Knowing the season was vital when deciding to plant and harvest crops as well as managing livestock in colder climates.
Experts have believed for a long time that pregnancy weakens a womanâs immune system, making her more susceptible to illnesses like the flu. However, research released just before the start of this flu season indicates that, in the case of the flu, the opposite may be true during pregnancy.
Problems during pregnancy can occur when Rh antibodies from an Rh-sensitized woman cross the placenta and attack the blood of an Rh-positive fetus. The Rh antibodies destroy some of the fetal red blood cells. This causes hemolytic anemia, where red blood cells are destroyed faster than the body can replace them. Red blood cells carry oxygen to all parts of the body. Without enough red blood cells, the fetus will not get enough oxygen.