The rule of thumb is most women need about 300 extra calories every day during the last five to six months of pregnancy for good fetal development. This will combine to a healthy weight gain of about one pound each week.
In general, the brain can withstand up to three to six minutes without oxygen before brain damage occurs, but this may vary from person to person.If the brain goes without oxygen longer than this, serious and often irreversible damage is likely to take place.eath is usually declared once the brain has gone more than 15 minutes without oxygen. Although the brain can only go a few minutes without oxygen before some type of brain damage occurs, patients can often regain cognitive function if treated quickly.
The brain can survive for 4 minutes without oxygen, then brain cells start dying. So if there is no heartbeat, the heart is not contracting, the blood is not circulating through the body, and there is no oxygen supply. Other tissues and organs can live longer without oxygen. For example an arm or leg can survive up to 6 hours. That is why if there is a deep cut or wound, a tourniquet can be applied to stop the flow of blood to a limb for several hours if needed.